Bluetooth-Electronic product solution company-Electronic and electrical product development-Bluetooth design-S

Bluetooth

07-09

2023

Car bluetooth phone technology

Research and Implementation of Car Bluetooth Telephone TechnologyThe car bluetooth phone is specially designed for driving safety and comfort. Users only need to have a mobile phone with bluetooth function to connect with the car bluetooth, so as to make calls through the car equipment. Users do not need to touch the mobile phone to control the mobile phone, use voice commands to control, operate the vehicle terminal or even the steering wheel to answer or make calls, and make calls through the car audio or Bluetooth wireless headset, which can ensure a good call effect. Car bluetooth phones are generally used in front-mounted car entertainment terminals and rear-mounted car devices, and it is an applicable technology. This paper mainly introduces the realization principle of the Bluetooth phone function of the vehicle-mounted device based on the Android system.1. Bluetooth architecture of Android systemAndroid system Bluetooth includes application layer, framework layer and local library, HAL layer and Kernel kernel driver code. The BlueZ protocol is mainly implemented in the local library and kernel code, and the local library and kernel communicate through the HAL layer interface. The framework layer mainly implements the management of the Bluetooth application protocol Profile, and interacts with the local library through the JNI interface. The framework layer includes local Bluetooth device adaptation, local Bluetooth information and management, remote device attributes, RFCOMM-based Bluetooth device server and client socket management, various Bluetooth profile services, etc. The modules that manage Bluetooth phone functions include SettingsApp, Phone, and Bluetooth. It is mainly the Android system of the vehicle-mounted smart device that supports the Bluetooth HFP protocol (Hands-freeProfile). HFP can realize the phone control function based on the Bluetooth connection, and provide a unified standard for the Bluetooth phone function.2. Realization of Bluetooth phone in Android system2.1 Bluetooth HFP protocolThe HFP protocol defines two roles: the audio gateway (AG) and the hands-free component (HF): the AG device is used as the audio input/output gateway, that is, the mobile phone terminal; the HF device is used as the remote audio input and output mechanism of the audio gateway, that is, the vehicle device end. The HFP protocol provides a number of telephone-related remote control functions for HF devices. First, establish RFCOMM connections, and exchange AT commands between the two devices through the RFCOMM protocol channel. The AT command set is based on ITUTV. 250 and GSM07.07. The HF end sends AT commands to read the AG end status and control the AG end phone functions. At the same time, the AG side indicates the status of the terminal through the AT command (+CIEV:).2.2 Realization of Android system HF protocolThe AG side of the Android system HFP protocol receives and parses the call-related AT commands and processes the calls to the phone system interface. AT commands include:"AT+D" dialing operation; "AT+A" answering operation; "AT+CHUP" hanging up operation; "AT+CLCC" call status query; "AT+VTS" dual-tone multi-frequency tone sending; "Call hold operation; "AT+VGS" speaker volume adjustment; "AT+VGM" microphone volume adjustment; "+CIND" mobile phone status indication, etc.It meets all the phone control functions of the HF end. Therefore, the Android system mobile phone supports the AG-side Bluetooth headset and Bluetooth phone functions, and the HF-side vehicle equipment should also have equivalent functions. The vehicle device side needs to increase the interface interaction and logic processing of the Bluetooth phone, and support the processing flow of the HF side of the HFP protocol.The framework layer (Framework) above Android 5.0 adds hands-free service client management and improves the HFP protocol process processing, so the vehicle-mounted equipment using Android 5.0 and above systems can provide complete Bluetooth phone functions on the basis of the existing framework. The specific implementation process is shown in Figure 1.BluetoothClientService adds phone control-related interfaces, including dial0, acceptCall(), holdCall0, terminateCall(), holdcau0, getCurrentCalls0, etc., providing functions such as dialing, answering, hanging up, holding, and call status query. HeadsetClientStateMachine, as a bridge between the framework layer and protocol processing, mainly completes the logic processing and state jump of HFP in the framework layer, including the following two aspects: (1) Receive phone instructions from the local protocol layer module, and notify the application through system broadcast The program rings or updates the call status display. (2) Manage the status of the protocol (connected or disconnected), call this interface, and send the control of the application to the protocol module. In the Bluetooth protocol layer, Bta-hf-client-cmd is responsible for the assembly and transmission of AT commands, and Bta_hfclient is responsible for the reception, analysis and reporting of AT commands. The Bluetooth phone APP is mainly responsible for UI interaction and interface logic processing, and provides users with convenient functions, including dial pad, synchronous address book and call records, search contacts, call reminders, buttons on the call interface, etc. If a phone function button is added to the steering wheel, the button event of the steering wheel is sent to the vehicle-mounted device through the vehicle wiring harness, and functions such as calling, answering, and hanging up can be triggered, so that the driver can control the mobile phone without leaving the steering wheel. .SummarizeAt present, Bluetooth devices are widely used, and the Bluetooth protocol is relatively mature. It is a form of vehicle interconnection to transfer the functions of mobile phones to vehicle-mounted devices through Bluetooth connections. The purpose is to facilitate driving and improve user experience. With the development of hardware and software technology, more electronic products based on Bluetooth connection solutions will be applied to vehicle, medical and health fields, providing users with more convenience.The above is the research and implementation method of the car Bluetooth phone technology introduced by Shenzhen Zuchuang Microelectronics Co., Ltd. for you. If you have Bluetooth product design and development needs, you can trust us. We have rich experience in custom development of smart electronic products. We can evaluate the development cycle and IC price as soon as possible, and can also calculate the PCBA quotation. We are a number of chip agents at home and abroad: Songhan, Yingguang, Jieli, Ankai, Quanzhi, realtek, with MCU, voice IC, BLE Bluetooth IC, dual-mode Bluetooth module, wifi module. We have hardware design and software development capabilities. Covering circuit design, PCB design, single-chip microcomputer development, software custom development, APP custom development, WeChat official account development, voice recognition technology, Bluetooth development, wifi technology, etc. It can also undertake the research and development of smart electronic products, the design of household appliances, the development of beauty equipment, the development of Internet of Things applications, the design of smart home solutions, the development of TWS earphones, the development of Bluetooth earphone speakers, the development of children's toys, and the research and development of electronic education products.
06-29

2023

Bluetooth speaker product development

Bluetooth speaker product development refers to the process of designing and manufacturing Bluetooth speaker devices. Bluetooth speaker is an audio device with Bluetooth wireless connection function, which can receive and play audio content from various audio sources (such as smartphones, tablets, computers, etc.) through Bluetooth technology. Here are the main technical aspects involved:Bluetooth technology: Bluetooth speakers need to support Bluetooth wireless connections, enabling them to establish connections with other Bluetooth devices (such as audio source devices) and transmit audio data. Bluetooth technology involves the Bluetooth protocol stack, Bluetooth profiles, etc. to ensure compatibility and communication capabilities between speakers and other devices.Audio processing and decoding technology: Bluetooth speakers need to be able to receive, decode, and process audio data in different formats to provide high-quality audio output. This may involve audio codecs, digital signal processing (DSP), audio amplifiers and other technologies to ensure accurate restoration and amplification of audio signals.Battery management and power optimization: Bluetooth speakers often require built-in batteries for mobile use. Therefore, battery management and power consumption optimization are important technical considerations. This includes designing efficient power management circuits, adopting low-power components, and optimizing power control algorithms to extend battery life and provide long usage times.Acoustic Design and Audio Drivers: The acoustic design of a Bluetooth speaker is an important aspect in ensuring good sound quality and volume performance. This involves choosing the right loudspeaker drivers, designing proper speaker cabinets and acoustic isolation to achieve superior sound quality and audio performance.User interface and control: Bluetooth speakers usually have user interface and control functions to facilitate users to perform operations such as speaker settings, volume adjustment, and audio source switching. This may include buttons, knobs, touch panels, remote controls, apps, and many other forms of user interface.Wireless connection stability and distance coverage: Bluetooth speakers need to provide reliable wireless connection stability and achieve good signal coverage within a certain distance. This requires consideration of technical means such as antenna design, signal interference elimination, and signal attenuation compensation.Connection stability and multi-device connection: Bluetooth speakers usually support multiple devices connected at the same time, such as connecting multiple smartphones or other audio source devices. Therefore, technologies that ensure connection stability, multi-device switching, and management are required during development.Waterproof and dustproof design: Bluetooth speakers often need to have waterproof and dustproof functions to adapt to outdoor and various environmental conditions. This requires techniques such as proper seal design, waterproof coating, material selection, etc.Device interoperability and compatibility: When developing a Bluetooth speaker, consider interoperability and compatibility with other devices to ensure that it can pair and communicate with various makes and models of audio source devices.Remote control and smart functions: Some advanced Bluetooth speaker products may support remote control and smart functions, such as voice assistant integration, smart home integration, speaker cloud services, etc. This involves technologies such as integration with cloud platforms, smart home protocols, and related application development.Manufacturing and production technology: The development of Bluetooth speakers also involves manufacturing and production technology, including PCB design, assembly process, quality control, etc., to ensure the manufacturability and consistency of products.It should be noted that the specific Bluetooth speaker development process and the technologies involved may vary depending on the product type, functional requirements, and manufacturer. Therefore, in actual development, technology selection and customized development may be required according to specific requirements.
06-28

2023

Bluetooth headset product development

Bluetooth headset product development refers to the process of designing and manufacturing Bluetooth wireless headset devices. A Bluetooth headset is a headset device that is wirelessly connected to an audio source device through Bluetooth technology and provides audio playback and call functions. Here are the main technical aspects involved:Bluetooth technology: Bluetooth headsets need to support Bluetooth wireless connections to establish connections with audio source devices (such as smartphones, tablets, etc.) and transmit audio data. Bluetooth technology involves the Bluetooth protocol stack, Bluetooth profiles, etc. to ensure compatibility and communication capabilities between the headset and other devices.Audio processing and decoding technology: Bluetooth headsets need to be able to receive, decode, and process audio data from audio source devices to provide high-quality audio playback and call functions. This may involve audio codecs, digital signal processing (DSP), noise reduction techniques, etc. to achieve clear audio.Battery management and power optimization: Bluetooth headsets often require built-in batteries for mobile use. Therefore, battery management and power consumption optimization are important technical considerations. This includes designing efficient power management circuits, adopting low-power components, and optimizing power control algorithms to extend battery life and provide long usage times.Wireless connection stability and distance coverage: Bluetooth headsets need to provide reliable wireless connection stability and achieve good signal coverage within a certain distance. This requires consideration of technical means such as antenna design, signal interference elimination, and signal attenuation compensation.User interface and control: Bluetooth headsets usually have a user interface and control functions to facilitate operations such as volume adjustment, song switching, and answering/rejecting calls. This may include buttons, touch controls, voice controls, and many other forms of user interface.Waterproof and sweatproof design: Since Bluetooth headsets are often used in sports and outdoor activities, waterproof and sweatproof design has become an important technical requirement. This may involve waterproof coating, waterproof seal design, material selection, etc. to provide reliability and durability of the headset in wet environments.Noise control and noise reduction technology: Bluetooth headsets often need to provide good noise control and noise reduction functions to reduce the impact of environmental noise on audio quality and call clarity. This may involve active noise reduction technology, ambient sound transfer function, etc., to provide a better audio experience.Device interoperability and compatibility: When developing a Bluetooth headset, consider interoperability and compatibility with other devices to ensure pairing and communication with various makes and models of audio source devices.Audio coding and transmission protocols: Bluetooth headsets need to support appropriate audio coding and transmission protocols, such as SBC (Subband Coding), AAC (Advanced Audio Coding), etc., to achieve high-quality audio transmission and compatibility.Headset Design and Ergonomics: Bluetooth headsets need to be designed with comfort, stability, and ergonomics in mind. This includes the shape and material selection of the eartips or earmuffs, the weight balance of the headphones, the adjustable over-the-head structure, etc. to provide a comfortable wearing experience.Charging technology and wireless charging: Bluetooth headphones are usually charged through a charging case or charging cable. During product development, appropriate charging technology and interface design, as well as possible wireless charging capabilities, need to be considered.Reliability and quality control: Bluetooth headsets need to withstand the test of daily use and portability, so reliability and quality control are important technical considerations. This includes designing durable housing materials, conducting reliability testing and quality control processes, etc. to ensure product stability and reliability.It should be noted that the specific Bluetooth headset development process and the technologies involved may vary depending on the product type, functional requirements, and manufacturer. Therefore, in actual development, technology selection and customized development may be required according to specific requirements.
06-27

2023

Bluetooth DONGLE module

The Bluetooth Dongle module is a small module used to add Bluetooth functionality to non-Bluetooth devices. It is usually provided in the form of a USB plug or other interface, and can be connected to non-Bluetooth devices such as computers, TVs, audio equipment, etc., so that it has Bluetooth communication capabilities. Here are the main technical aspects involved:Bluetooth communication technology: The key technology of the Bluetooth Dongle module is the Bluetooth communication technology. It uses the Bluetooth protocol stack to communicate with other Bluetooth devices, including connection establishment, data transmission and control commands, etc. Bluetooth communication technology involves the knowledge of Bluetooth protocol, Bluetooth configuration file, Bluetooth core specification and so on.Radio frequency and antenna design: The Bluetooth Dongle module requires radio frequency design and antenna design to ensure good wireless signal transmission and reception performance. This includes antenna selection, antenna layout, matching circuit design, etc. to optimize RF performance and signal coverage.USB or other interface design: Bluetooth Dongle module usually uses USB interface or other specific interface to connect with non-Bluetooth devices. During the design process, factors such as interface electrical characteristics, signal transmission rate and compatibility need to be considered.Power management and power consumption optimization: Bluetooth Dongle modules usually need to use the device's own power supply or obtain power supply from connected devices. Therefore, power management and power optimization are required to extend battery life or reduce the load on the power supply of connected devices.Driver development and compatibility: In order to make the Bluetooth Dongle module work normally in the operating system, a corresponding driver needs to be developed. This involves driver development and compatibility testing with the operating system.Data Security and Encryption: Data security and encryption in Bluetooth communications are important considerations. The Bluetooth Dongle module needs to support Bluetooth security protocol and encryption algorithm to ensure the security of data transmission and prevent unauthorized access.Software development and API integration: Bluetooth Dongle modules usually need to provide corresponding software development kits (SDK) and APIs so that developers can integrate Bluetooth functions into applications. This includes providing APIs, sample codes and development tools related to Bluetooth communication to simplify the software development process.User interface and configuration tool development: In order to facilitate users to operate and configure the Bluetooth Dongle module, it may be necessary to develop corresponding user interface and configuration tools. These tools can provide functions such as Bluetooth connection management, device pairing, and parameter setting to enhance the user's interactive experience.Compatibility testing and certification: During the development process, compatibility testing is performed to ensure that the Bluetooth Dongle module can communicate and pair normally with various Bluetooth devices. In addition, according to relevant standards and requirements, carry out Bluetooth certification, such as Bluetooth SIG (Special Interest Group) certification, to obtain compliance and approval of Bluetooth technology.Firmware upgrade and maintenance: With the continuous development of Bluetooth technology and the introduction of new functions, it may be necessary to upgrade and maintain the firmware of the Bluetooth Dongle module. This involves the design of the firmware update, transfer and installation process to ensure the latest functionality and performance of the modules.The development and manufacturing process of the Bluetooth Dongle module requires comprehensive consideration of knowledge and technology in multiple fields such as hardware, software, radio frequency and industrial design. Through high-quality engineering practice, comprehensive testing and certification process, a powerful, reliable and stable Bluetooth Dongle module can be developed to provide users with convenient wireless connection and communication solutions.
06-21

2023

Intelligent temperature control fan design

Design of Bluetooth data transmission intelligent temperature control fan systemThe bluetooth data transmission intelligent temperature control fan system designed in this paper is composed of two STC15F2K60S2 single-chip microcomputers as the master controller and slave controller respectively, using the body temperature sensor module as the temperature acquisition device, and the HC-05 master-slave integrated bluetooth serial port module to send and receive fan files Bit information, through the comparison of the system preset temperature and the body temperature detected by the system, the automatic adjustment of the fan motor speed and automatic start and stop are completed, and the operation of the fan motor is controlled through the triode. And display the fan gear, preset temperature, and detected body temperature on LCD1602 at the same time.1. The overall design idea of the intelligent temperature control fan systemUse the body temperature sensing module to collect body temperature and output voltage data to the main controller (STC15F2K60S2) for A/D conversion and calculation, and display the current body temperature value, preset temperature limit and fan gear on LCD1602. The preset temperature limit and the detected current human body temperature can be accurate to two decimal places. Send the gear position to the slave role Bluetooth through the master role Bluetooth, and the speed of the DC fan motor is changed by the controller (STC15F2K60S2) according to the gear position using PWM pulse width modulation. The system preset temperature limit is changed by three buttons, the first one moves the position corresponding to the changed limit value, the second one increases the preset limit value, and the third one lowers the preset limit value.2. Design scheme of Bluetooth intelligent temperature control fan systemThis design uses bluetooth wireless short-distance transmission to intelligently complete the temperature control of the fan motor. By adopting the shift and stop control components with high temperature change resolution and stable performance, the fan motor can automatically change the speed and start according to the change of human body temperature. stop.(1) Selection of temperature sensor: The temperature sensor adopts a body temperature sensing module, which is small in size and only needs one acquisition port to connect to the main controller, plus two positive and negative power supply pins, a total of three pins can work. As long as the human body touches the probe, the module can collect data, and the data can be accurate to two decimal places after the main controller A/D conversion and calculation.(2) Selection of the controller: The controller uses two STC15F2K60S2 single-chip microcomputers as the master controller and the slave controller respectively, through the method of software programming to convert, calculate and compare the body temperature data, and at the same time output the gear through the serial port of the master role Bluetooth Signal. STC15F2K60S2 single-chip microcomputer contains 2048 bytes of random data memory RAM, high performance, low operating voltage, no external crystal oscillator, affordable single chip, suitable for the design system of this article.(3) Selection of display device: This design uses LCD1602 liquid crystal display to display temperature, set limit value and gear position. The liquid crystal display can display 16x02 or 32 characters, the power consumption is extremely low, the displayed data is clear and eye-catching, and the programming of the display program is relatively simple. It can display not only numbers but also characters and even graphics, and the displayed characters are beautiful.(4) Choice of speed regulation method: This design adopts single-chip microcomputer software programming to realize PWM (pulse width modulation) speed regulation method. The most commonly used is the rectangular wave PWM signal. When controlling the speed of the motor, the speed is adjusted by adjusting the duty cycle of the PWM wave. The larger the duty cycle, the faster the speed. By using the software delay method, the high and low level delay time and the cyclic change of the I/O port level are realized to obtain the PWM signal.(5) Selection of wireless transmission devices: The wireless transmitter uses two HC-O5 master-slave integrated Bluetooth modules as wireless transmission devices. This module can set the master-slave mode to connect and send and receive between the master and slave roles. The HC-O5 master-slave integrated Bluetooth module is easy to operate, low power consumption, and the communication distance is within 10 meters, which is suitable for this design.3. Software design of intelligent temperature control fan systemThe program design has two parts, master controller and slave controller.4. Software debugging of intelligent temperature control fan system(1) Debugging of key display: system program written according to this design: the key interface of the program adopts the P2.5, P2.4, P2.3 ports of the main controller, the LCD1602 display data port adopts P0 port, and the RS terminal is connected to P4 .5 port, the RW terminal is connected to the P2.7 port, and the E terminal is connected to the P2.6 port, so as to complete the key function and LCD1602 display. After compiling without errors, and then changing the interface to a simulation debugging interface, the LCD1602 can normally display the upper and lower limits of the preset temperature, the gear position and the temperature given by the program. The button function has also been realized. When the setting key is pressed, the cursor flickers, and when the plus and minus keys are pressed, the number in the blinking cursor can also be added or subtracted by one, and then the setting key is pressed, and the cursor moves to the right (the cursor There are 8 moving positions), modify the upper and lower limits of the temperature.(2) Debugging of the acquisition part of the body temperature sensing module: Due to the integration of the body temperature sensing module, the adjustment is extremely simple. Its high precision, low power consumption, and small size make it possible to achieve high stability and high precision in controlling the motor. The P1.4 port of the main controller is used as the analog input port. Since the input analog signal needs to be converted and processed by AD to display the body temperature, it is necessary to increase the body temperature conversion program. The continuous detection of human body temperature is completed through software program design, and LCD1602 will display the percentile part of the temperature. Connect this module to the circuit, and LCD1602 will display a temperature, but this is not the ambient temperature. In this design, the module can only detect the temperature of the human body. After people pinch their fingers (or touch other parts of the human body) the probe of this module, LCD1602 can display the currently detected human body temperature.(3) Debugging of the fan motor speed regulation circuit: This design uses two triodes to drive the fan DC motor. The software sets the P0.0 port to output different PWM waveforms to the two triodes to drive the rotation of the fan motor. The software is set to output different PWM waves according to different temperatures to obtain different duty ratios to control the fan motor. The larger the duty ratio, the higher the gear. The program realizes the PWM waveform output of the P0.0 port. When the temperature of the human body is lower than the lower limit temperature, the fan will automatically stop rotating (0 gear); ) or start to rotate automatically; when the body temperature is higher than the middle limit and lower than the upper limit, the fan rotates at a medium speed (2 gears); when the human body temperature is higher than the upper limit, the fan rotates at full speed (3 gears).The speed of the fan motor in this design system can be adjusted in four stages, and the speed conversion is completed according to the comparison between the upper and lower temperature limits preset by the system and the temperature detected by the body temperature sensor module. Change the gear information received from the controller in the program, and the fan motor can realize the speed regulation of the corresponding gear.(4) Debugging of the bluetooth circuits of the master and slave roles: the master controller compares the current gear position with the last time. If the gear position changes, it will send the changed gear position to the slave controller through the master role bluetooth. The role Bluetooth receives the gear information sent by the master role Bluetooth, and then transmits it to the slave controller. When there is a gear to the slave controller, the slave controller will output the PWM wave corresponding to the gear. The gear position is generated on the main controller side (can be known through the display of LCD1602), and then use the serial port assistant to connect the slave role Bluetooth to get consistent gear information, and then connect the slave role Bluetooth to the slave controller circuit, and the fan motor will also The corresponding rotational speed can be achieved.5. Hardware debugging of intelligent temperature control fan system5.1 Debugging of key displayThe system button part realizes the following functions: press the setting button to connect the button of the P2.5 port of the main controller, and set the upper and lower limit values of the temperature (the LCD cursor moves and flashes); press the plus button to connect the button of the P2.4 port , to realize the addition of one to the value of the blinking cursor; press the minus key, that is, the button of the P2.3 port, to realize the reduction of the corresponding value by one. If the pressing time is too long, the cursor will not move by one position, but will increase by two positions. The main reason is that the debounce delay time of the key is too long, and the corresponding key debounce delay time can be appropriately increased as an improvement method.This design realizes that the LCD1602 can display the upper and lower limits of temperature, the gear position and the temperature of the human body. The upper and lower limits of the temperature can be adjusted through buttons according to different needs, and the display effect of the LCD1602 is very good and stable.5.2 Debugging of the temperature acquisition part of the body temperature sensor moduleConnect the AD port of the body temperature sensor module to the P1.4 port of the main controller through a square female connector. The four ports on the right side of the main controller are the AD, GND, DC, and VCC ports of the body temperature sensor module. The module can be directly inserted into the header. In order to verify whether the module can work on the main controller board during system debugging, pinch the probe of the module (or other parts of the body) with a human finger, and you can find that the value displayed on the LCD1602 also changes, and it will be when it is stable. Detected body temperature, thus verifying that the module is working properly on the system board. Since the module has only 4 pins, pay attention to the corresponding position of each pin during the debugging process, so as not to reverse the connection and cause the module to fail to work or even burn the module.5.3 Debugging of fan motor speed regulation circuitSince the design of the speed control circuit mainly lies in the software design, the peripheral drive circuit simply amplifies the transmitted PWM signal to drive the fan motor to rotate. When the temperature of the human body is higher than the lower limit of the system preset temperature, the motor starts to rotate. Since the temperature of the human body is relatively constant and does not change much, the gear position of the fan motor will not change too frequently. The speed of the fan will change as the gear is switched. When the fingers (other parts of the body) leave the probe of the body temperature sensing module, it is found that the detected temperature first increases and then decreases until it becomes stable. system performance.6. Intelligent temperature control fan system function(1) Functions realized by the system: This design can realize the single-chip microcomputer system to detect the change of human body temperature, and according to the change of body temperature, transmit the gear signal through wireless Bluetooth to control the start-stop and speed regulation of the fan DC motor. Different duty ratios are output by the single-chip microcomputer to generate different speeds; different temperature upper and lower limits can also be preset through the buttons, and then the gear is adjusted according to the comparison between the set temperature limit and the detected human body temperature to control the motor speed . When the body temperature is lower than the lower limit of the preset temperature, the motor stops rotating; when the body temperature is higher than the lower limit of the preset temperature, the P0.0 port of the single chip microcomputer outputs PWM signals with different duty ratios to regulate the speed of the fan. The system can also dynamically display the current human body temperature, set temperature limit and gear.(2) System function analysis: The system is generally composed of two parts: the main controller side and the slave controller side. The main controller side is composed of five parts, namely the main controller (single chip microcomputer), LCD1602 display circuit, body temperature detection module body temperature acquisition circuit, independent button circuit, master role Bluetooth connection circuit; the slave controller side is composed of three parts, that is, the slave role Bluetooth connection circuit, slave controller (single chip microcomputer), fan motor speed regulation circuit. The body temperature acquisition circuit in the human body temperature detection module is the most important part of the whole design system. First of all, the body temperature must be detected, and the gear can be obtained by comparing the master controller with the temperature limit, and the slave controller controls the speed of the DC fan motor through the gear signal; then the master and slave role Bluetooth connection circuit, this part uses the master Communication between roles from Bluetooth. The gear position signal of the master controller is sent to the slave role Bluetooth through the master role Bluetooth, and then transmitted to the slave controller; the second is the fan motor drive circuit, which amplifies and outputs the PWM wave output from the controller through the peripheral circuit. Different PWM wave to get different motor speeds. The circuit design uses two triodes to achieve a better control effect; finally, the dynamic display circuit of LCD1602 realizes the display of the set temperature limit, human body temperature and fan motor gear, and there are independent buttons to realize the temperature limit according to different needs. Adjustment.SummarizeThe designed system uses single-chip microcomputer as the control element, and the gear position is obtained according to the comparison between the human body temperature detected by the body temperature sensor module and the set temperature limit value, and the gear position is transmitted through wireless transmission between Bluetooth, and the fan is realized within a certain distance. Speed adjustment. The design of this system can be extended to the fan motor control system of the family to realize the intelligent control and adjustment of the fan speed, and also realize the monitoring of human body temperature (especially for children and the elderly).The above is the design scheme of the Bluetooth data transmission intelligent temperature control fan system introduced by Shenzhen Zuchuang Microelectronics Co., Ltd. If you have Bluetooth product design and development needs, you can trust us. We have rich experience in custom development of smart electronic products. We can evaluate the development cycle and IC price as soon as possible, and can also calculate the PCBA quotation. We are a number of chip agents at home and abroad: Songhan, Yingguang, Jieli, Ankai, Quanzhi, realtek, with MCU, voice IC, BLE Bluetooth IC, dual-mode Bluetooth module, wifi module. We have hardware design and software development capabilities. Covering circuit design, PCB design, single-chip microcomputer development, software custom development, APP custom development, WeChat official account development, voice recognition technology, Bluetooth development, wifi technology, etc. It can also undertake the research and development of smart electronic products, the design of household appliances, the development of beauty equipment, the development of Internet of Things applications, the design of smart home solutions, the development of TWS earphones, the development of Bluetooth earphone speakers, the development of children's toys, and the research and development of electronic education products.
06-20

2023

Bluetooth iBeacon and Mesh

Bluetooth iBeacon and Mesh networking technologyThe main content of this article is to analyze the iBeacon broadcast technology of BLE from the principle and protocol, and introduce the Mesh ad hoc network technology of Bluetooth low energy, so as to break the bottleneck that traditional Bluetooth cannot ad hoc network or weak networking function.1. Bluetooth iBeaconThere are two forms of signals sent by BLE, namely broadcast and connection. iBeacon technology is a BLE-based intermittent broadcast technology proposed by Apple, namely Internal beacon.1.1 Analysis of iBeacon data structureThe data volume of a BLE broadcast frame can reach up to 47 bytes, which includes a 1-byte header, 4-byte address, 39-byte broadcast channel PDU data packet, and 3-byte CRC check code:The iBeacon broadcast technology adopts the simplest broadcast data format, which deletes the data header and MAC address in the PDU data packet, and only sends 31 bytes of data; when this topic is studying iBeacon broadcast, set its data format to 6 bytes preset data, 1-byte manufacturer data, 2-byte company service code, 16-byte 128-bit UUID, 2-byte major device number, 2-byte minor device number, 1-byte signal emission strength, In addition to the preset position data, the data in other fields can be modified by yourself. The mobile terminal can receive the iBeacon broadcast signal sent by the BLE base station, and capture iBeacon data through software.1.2 Analysis of RSSI characteristics of iBeaconiBeacon technology uses intermittent radiation broadcast data into the space, so the spatial RSSI network distribution is changing according to certain rules. In this project, the broadcast interval is set to ±=1095 msmsT, that is, under the condition of constant environmental factors, the RSSI network Take T as the time interval to make periodic changes. There are two ways to measure signal strength in real-time communication: RX and RSSI, both of which are measures of the received power of the signal by the antenna, but the former measures the power of the signal in milliwatts; while RSSI indicates the received signal strength The percentage of is a relatively comparative measurement method, and the comparison standard is defined by the chip manufacturer.2. Bluetooth Mesh Ad Hoc NetworkCompared with ZigBee, traditional Bluetooth devices have poor ad hoc network capability, which is one of the reasons why it is difficult to implement large-scale Internet of Things; with the rapid development and popularization of BLE technology, this project proposes that the ad hoc network based on Bluetooth Mesh will Break through the defects of traditional Bluetooth and complete the cross-island connection of Bluetooth Mesh.2.1 Traditional Bluetooth device networkA piconet is a traditional Bluetooth network topology. There can only be one master device in a piconet, and less than or equal to seven slave devices in wake state. The master-slave device communicates with the slave device according to polling rules, and the communication between the slave devices requires the master device to be bridged; a single piconet adopts a star topology, and multiple piconets are linked together to adopt a tree topology , its principle conforms to the allocation model of 1 master and 7 slaves, that is, the piconets are interconnected in the form of crossover; the slave node 4 of network A is the master node of network B, so many piconets constitute a scatternet (scatternet) as shown in Figure 5.5 shown. The disadvantage of the scatternet is that the structure is complex and redundant. Two adjacent slave nodes that are not in the same network need to exchange information in the form of multiple hops, and the transmission speed is slow, resulting in waste of resources.2.2 Bluetooth Mesh Ad Hoc NetworkEach node in the wireless Bluetooth Mesh network uses multi-hop technology to access the ad hoc network. There are one or more routes between two device nodes, and data communication is carried out in a cooperative manner. The Bluetooth iBeacon signal removes the size of the packet header, and the real information carried by each frame is 31 bytes. The wireless Mesh network itself is a high-capacity, high-speed network. Wireless communication is very efficient. In theory, a Bluetooth wireless Mesh network can connect 65,535 device nodes. In actual experiments, limited by factors such as the CPU and memory capacity of the device, the number is more than 200, and the transmission distance of each device node is greater than 50 meters. For large networks, it can Connect through multiple ad hoc networks.In the application of BLE, the Mesh ad hoc network realizes the mutual communication between each device node, abandons the concept of one master device pairing seven slave devices in the piconet, and the cooperative communication broadens the channel of data interaction in the system.The links between each device node are connected to each other to form a dense network. Among them, the dotted line indicates that two device nodes complete indirect data communication by bridging through intermediate nodes. The form of signal transmission is like the recursion of waves. . In a Mesh network, there are two reasons for indirect data communication: for example, the dotted line m is because the distance between device nodes is greater than the maximum distance of Bluetooth signal propagation; the dotted line n is non-line-of-sight communication, and there are Bluetooth signals between device nodes Obstacles that cannot be passed through.2.3 Related Protocols of Bluetooth Mesh Ad Hoc Network(1) Coordinated allocation of channels: When the Bluetooth multi-channel is connected to the Mesh ad hoc network, each iBeacon device node can only monitor one available channel at a time, and the device node can ensure the signal sent by each node through a specific negotiation mechanism. On the same channel, that is, device nodes can switch from different channels to available channels in real time; the research uses the ATIM window multi-channel synchronization mechanism, and its principle is: at the beginning of the window, all device node signals are forcibly switched to the same channel.The channel division of the Mesh network is to allocate the network's use of channels from the division of frequencies to ensure the high efficiency of the Mesh network; among them, the mainstream channel allocation scheme is the division of groups, and the allocation rule is to select the one with the least conflict between adjacent nodes. channel.(2) Network search and routing and forwarding: Network search technology is used to discover iBeacon nodes in the Mesh network and establish a node information database. The main methods used are: scanning of network information and maintenance of node information database; For new devices in the network, the node information of the device will be propagated in the Mesh network in the form of routing and forwarding. The routing and forwarding technology directly affects the utilization rate of the network. The Mesh network adopts a multi-hop technology, that is, the signal can be received by the target node through multiple node hops; there are three points to consider when selecting the route: 1. Comprehensive consideration of the routing Selection, the minimum number of hops is not the only criterion for judging the best route. 2. Improve the fault tolerance of Mesh network routing to avoid signal transmission failure caused by link interruption. 3. Improve resource utilization and choose multiple routes; the mainstream Mesh network The network routing protocol is a dynamic source routing protocol, which is a symmetric reactive ad hoc routing protocol.(3) Network security: Mesh network's unique multi-hop technology and self-organizing network technology ensure the security of Mesh network; at the same time, in order to solve the confidentiality of node traffic in Mesh network, the control and supervision of iBeacon node network access, Mesh security Association proposes a security architecture with Mesh keys as the core; in which only authenticated keys can organize communication, the authentication process has 3 steps: 1. Link management protocol interaction phase, 2. EAP authentication, 3. Mesh 4-way handshake for security associations. Therefore, when establishing a Mesh network in this project, the network key is pre-set.The way to realize the Mesh ad hoc network is: the application software of the mobile terminal searches and finds the iBeacon broadcasting device, and establishes a link, selects the security configuration menu, sets the security key of the Mesh network, switches to the device search menu, and selects the corresponding device in the information list Access to the network and establish a Mesh ad hoc network with mobile terminals as MP nodes. Here is a network security issue. A BLE device can be used as an intermediate bridge for information transmission in a Mesh network, but it can only have one network key at the same time, that is, it can only be controlled by one MP node.SummarizeThis paper mainly introduces the iBeacon technology of low-power Bluetooth, analyzes the iBeacon signal data structure, and supplements the RSSI characteristics of the signal, and uses the logarithmic path loss model to express the relationship between the signal strength value received by different chips and the signal propagation distance; then This paper compares and analyzes the traditional Bluetooth networking technology (piconet) and Bluetooth Mesh ad hoc networking technology, and describes the Bluetooth Mesh protocol and its implementation from three aspects: channel coordination and allocation, network search and routing forwarding, and network security.The above are the details of the Bluetooth iBeacon and Mesh networking technology introduced by Shenzhen Zuchuang Microelectronics Co., Ltd. If you have Bluetooth product design and development needs, you can trust us. We have rich experience in custom development of smart electronic products. We can evaluate the development cycle and IC price as soon as possible, and can also calculate the PCBA quotation. We are a number of chip agents at home and abroad: Songhan, Yingguang, Jieli, Ankai, Quanzhi, realtek, with MCU, voice IC, BLE Bluetooth IC, dual-mode Bluetooth module, wifi module. We have hardware design and software development capabilities. Covering circuit design, PCB design, single-chip microcomputer development, software custom development, APP custom development, WeChat official account development, voice recognition technology, Bluetooth development, wifi technology, etc. It can also undertake the research and development of smart electronic products, the design of household appliances, the development of beauty equipment, the development of Internet of Things applications, the design of smart home solutions, the development of TWS earphones, the development of Bluetooth earphone speakers, the development of children's toys, and the research and development of electronic education products.
06-19

2023

Bluetooth anti-jamming technology

1. Bluetooth adaptive frequency hopping (AFH) technologyThe Bluetooth system works in the 2.4GHz ISM (ie industrial, scientific, medical) frequency band. Many devices work in this frequency band. Working in such a frequency band, mutual interference must be relatively serious. Therefore, the Bluetooth system uses frequency hopping technology to prevent fading and Suppress distractions. Before the connection is established, the Bluetooth device selects a frequency hopping frequency in a fixed frequency band, quickly exchanges time and address handshake information, and then quickly obtains time and frequency synchronization. After the connection is established, the two devices change the channel frequency according to the hopping sequence, so that the frequency hopping frequency appears random.Bluetooth defines 32 frequency points as a frequency band, which is divided into 79 sub-frequency bands. The lowest 28 bits of the Bluetooth master clock CLK and the master device address determine the frequency band and frequency hopping sequence of Bluetooth work, as shown in Figure 2.10; Bluetooth system definition Frequency hopping sequences under 5 working states: paging, paging response, inquiry, inquiry response and connection frequency hopping sequence. There are different strategies to generate frequency hopping sequence in different states.Figure 2.11 shows the generation principle of the frequency hopping sequence of the Bluetooth system; the input X is determined by the clock information bit, which determines the phase of the hopping frequency point in the 32 frequency sequences of a certain frequency band -- the offset of the frequency sequence in the segment At the same time, the speed of changing the frequency hopping frequency point is also determined by it; A to F determine the order of the frequency hopping sequence. value; in the query/paging scanning state, the input sequence from A to F is only related to the address, so its frequency hopping sequence is uniquely determined. In other states, A~F is controlled by the clock and the Bluetooth address, and its frequency hopping The sequence jumps accordingly with the change of the clock; Y1 and Y2 control the selection of the transceiver frequency hopping sequence, Y1 ensures that the transceiver frequency will not be repeated, and Y2 makes the transceiver frequency in different frequency bands; PERM5 is a The butterfly arithmetic unit controlled by C, D, and Y1 plays the role of disturbance.(1) Paging/paging scanning state: Bluetooth devices search for other devices to join their piconets through paging; paging devices select a new frequency hopping point every 312.5µs to initiate paging, during paging scanning, The paged device selects a new frequency point to monitor every 1.28s. The paging and the paged device use the lower 28 bits of the paged device address. The paging hopping sequence generated is a well-defined periodic sequence, which The 32 frequency points are evenly distributed on 79 frequency channels.(2) Query/query scanning status: Bluetooth devices search for other devices around by querying. The querying device selects a new frequency to send query messages every 312.5µs, and the queried device selects a new frequency to monitor every 1.28s; query Use the universal inquiry access code as the inquiry address with the inquired device. The generated 32 query hopping sequences are evenly distributed on 79 frequency channels.(3) Connection state: Using the lowest 28 effective bits of the master device address, the two sides of the Bluetooth communication device change a frequency every 625µs, and the resulting channel hopping sequence period is very long, and 79 hopping sequences are in any short period of time It is close to the uniform distribution, which can meet the requirements of the frequency hopping system.The algorithm of adaptive frequency hopping is added in the Bluetooth 1.2 protocol; when a certain channel signal quality is found to be poor during Bluetooth communication, that is, it becomes a "bad" channel, these bad channels can be discarded during frequency hopping and other channels can be selected Frequency hopping channels with good quality are used instead, thereby avoiding communication interference on certain frequency points, thereby enhancing its anti-interference ability.2. Bluetooth baseband error correction mechanismBluetooth technology adopts forward error correction FEC and automatic repeat request (Automatic Repeat-reQuest, ARQ) technology, and the error correction mechanism adopted is relatively simple. Among them, the forward error correction (FEC) is that the sending end encodes the data information according to certain rules to form a code with error correction capability; the receiving end receives the encoded data and performs corresponding decoding according to the predetermined rules to determine the received data. Whether there is an error in the data information, if there is an error, determine its location and correct it. This coding method is more suitable for real-time transmission systems, but the disadvantage of this technology is that the error correction capability is limited.Autonomous retransmission request is also called decision feedback. It uses confirmation and timeout to realize reliable information transmission on the basis of unreliable service; The error detection capability; after receiving the encoded information, the receiving end decodes it and makes a judgment to detect whether there is a certain bit error, and then sends the judgment result back to the sending end through the feedback channel; the sending end according to the feedback judgment result, Decide whether to retransmit the data; but the retransmission is not unlimited. After multiple retransmissions, the system will not retransmit after the time specified by the system.The specific error correction methods in the Bluetooth baseband include: 1/3 ratio FEC, 2/3 ratio FEC and ARQ. Among them, the 1/3 ratio FEC codes each bit of information three times, the coding method is relatively simple, and the length of the coding sequence is three times the length of the original sequence. The 2/3 ratio FEC encoding uses a generator polynomial to encode 10-bit data into 15 bits, which is a (15, 10) truncated Hamming code, and the data receiver performs the corresponding reverse operation, according to the error detection and error correction mechanism provided by the algorithm restore the original data. In the ARQ mode, the data packet has been retransmitted until the final acknowledgment is received or the retransmission times out.The above are the details of the Bluetooth anti-interference technology introduced by Shenzhen Zuchuang Microelectronics Co., Ltd. for you. If you have Bluetooth product design and development needs, you can trust us. We have rich experience in custom development of smart electronic products. We can evaluate the development cycle and IC price as soon as possible, and can also calculate the PCBA quotation. We are a number of chip agents at home and abroad: Songhan, Yingguang, Jieli, Ankai, Quanzhi, realtek, with MCU, voice IC, BLE Bluetooth IC, dual-mode Bluetooth module, wifi module. We have hardware design and software development capabilities. Covering circuit design, PCB design, single-chip microcomputer development, software custom development, APP custom development, WeChat official account development, voice recognition technology, Bluetooth development, wifi technology, etc. It can also undertake the research and development of smart electronic products, the design of household appliances, the development of beauty equipment, the development of Internet of Things applications, the design of smart home solutions, the development of TWS earphones, the development of Bluetooth earphone speakers, the development of children's toys, and the research and development of electronic education products.
06-18

2023

ZigBee wireless technology

1. Brief introduction of ZigBee technologyMany scenarios in the home and industry require extensive use of wireless control and monitoring, and these requirements often require low data transfer rates, long battery life, and low complexity of use. In order to meet these requirements, IEEE proposed a wireless standard IEEE802.15.4, which is also called ZigBee. ZigBee is a wireless communication protocol for short distances and low data rates. It has three operating frequency bands, and the 2.4GHz frequency band is mainly used in China. ZigBee has the following characteristics: (1) low power consumption; (2) providing a complete wireless mesh network; (3) a single network can connect up to more than 65,000 devices; (4) easy to deploy; (5) economical, price Inexpensive; (6) Uses smaller data packets than other wireless technologies.2.ZigBee network topologyThe ZigBee standard specifies two types of devices: thin and full-featured. The former has limited functions, while the latter has all functions, and the latter can also be configured as an arbitrary function device. A reduced-function device can only communicate with a full-function device on the network, while a full-function device can communicate with any device. Reduced-function devices are used to perform relatively simple tasks, such as switches that turn functions on or off. Reduced-function devices generally have less memory size and processing power than full-featured devices.The ZigBee standard stipulates that there are three functional devices in the ZigBee network: a router, a coordinator and a terminal device. As the core device in the network, the coordinator is a full-featured device that forms the root of the network through which it can connect to other networks. There is only one coordinator in each ZigBee network. ZigBee networks are initially created by the coordinator, which stores information about the network and acts as a repository for security keys. Routers route data from other devices in a ZigBee network. Routing is the processing of the path along which data is forwarded to a destination device. ZigBee end-devices can connect with a coordinator or router to join the network, but cannot relay data. This feature allows end-device nodes to be inactive most of the time, thereby extending battery life.A ZigBee network composed of devices with different functions can have three topologies: star, tree and mesh, among which tree and mesh networks belong to peer-to-peer networks.In a tree network, the coordinator acts as the root of the tree, routers or end devices can connect to the coordinator, and it can be expanded like a tree. End devices cannot have child nodes because they cannot relay information. This topology allows multiple levels of nodes in the network, and terminal devices can directly join the network through routers without relying on the coordinator, and all messages can be sent to any other device through routing. This type of topology is the most reliable one for ZigBee devices to communicate with other devices on the network.The star network takes the coordinator as the center, and multiple terminal devices are directly connected to the coordinator, which is the simplest network. When using this structure, the terminal device can only communicate directly with the coordinator, and the communication between two terminal devices requires the coordinator to forward messages, and the coordinator acts as a router. Therefore, the data flow through the coordinator in the star network is relatively large, and the more network nodes, the lower the communication efficiency of the entire network.Figure 3-1 Three topological structures of ZigBee networkMesh topology is the most flexible and widely applicable topology. In a mesh network, it allows the network to search for alternate paths for messages, where there are multiple paths a message can take from its origin to its destination. Therefore, message delivery is very reliable and has low latency in a mesh network.No matter which structure is used, the ZigBee network is created by the only PAN (PersonalAreaNetwork, personal area network) coordinator. The coordinator manages the entire network and is responsible for the following tasks: (1) start, terminate, or route messages across the network; (2) assign 16-bit or 64-bit network addresses to devices that later join the network; (3) generate the network Corresponding PAN identifier (PANID), each PANID corresponds to a different ZigBee network, PANID allows devices in the network to use 16-bit short addresses to communicate with other devices in the entire network. The PAN coordinator generally has a long active period, so it is usually powered by a mains power supply, and other devices are usually powered by batteries. The smallest ZigBee network contains only one end device and one PAN coordinator.3. ZigBee protocol stackAs can be seen from Figure 3-2, the structure of the ZigBee protocol stack has four layers, of which the physical layer and media access control layer are defined by the IEEE802.15.4 standard, and the network layer and application layer are defined by the ZigBee Alliance.3.1 Application layerThe APL layer of ZigBee consists of three parts: Application Support Sublayer (APS), Application Framework (AF) and ZigBee Device Object (ZDO). APS provides the interface between the network layer and the application layer, and its main functions are: (1) maintaining the binding table; (2) transmitting messages between the binding devices; (3) managing group addresses. AF is an environment that hosts application objects to control and manage the application layer. The application object is developed by the manufacturer, which can customize the application for the device, and has a uniquely identified endpoint number (endpoint 1 to endpoint 240). A single device can have up to 240 application objects. The ZigBee device object is the interface between APS and AF. ZDO is responsible for initializing APS, network layer and security service specifications. Its main functions are: (1) Define the role of the device in the network: coordinator, router or terminal device; (2) Discover devices and applications on the network, start or bind them accordingly (3) Perform relevant security tasks.3.2 Network layerThe network layer is responsible for managing the formation, joining, leaving and routing maintenance of the network. The network layer also supports management services and data services. The data is transmitted by the corresponding data entity and can be accessed through the network layer data entity service access point. The management service is in charge of the corresponding management entity, which can provide network layer management service for the application layer through the management entity service access point of this layer.The network layer of the coordinator creates a ZigBee network and assigns network addresses to devices that join the network afterwards. The distance (hops) of each frame of data transmitted in the network is specified by the network layer. The coordinator can enable security functions at the network layer - using a 128-bit AES encryption key to encrypt network data, new devices that join the network created by the coordinator can communicate with other devices on the network only after the key is distributed communication.In general, the network layer is responsible for the following functions: (1) joining or leaving the network; (2) providing AES encryption; (3) discovering and maintaining routes between devices; (4) routing functions, except for terminal devices; (5) ) Configure the device as a device with different functions: coordinator, router or terminal device; (6) discover neighbors who can communicate without routing and maintain the neighbor table; (7) assign addresses to new devices that join the network, only applicable to Coordinator and router.3.3 MAC layerIn the MAC layer, the MAC management object is responsible for the MAC layer management service, and the MAC layer provides a service interface to the network layer through the MAC management object access point. The MAC layer specifies four types of frames: MAC command frames, response frames, data frames, and beacon frames. Wherein, the beacon frame is a beacon sent by the coordinator, and is used to synchronize all devices in the same network to the beacon. The data frame is used to send valid data, the response frame is used to confirm the receipt of the data frame, and the MAC command frame is dedicated to sending MAC commands.The MAC layer uses a special channel access mechanism to support multiple devices using the same channel to communicate with each other, that is, carrier sense multiple access with collision avoidance (CSMA-CA). In CSMA-CA, a device listens on a channel to ensure that the channel is free before sending a message. If the channel is occupied, it cancels the transmission and retries after a random amount of time until the maximum number of retries is reached or the channel becomes idle.The main functions of the MAC layer are: (1) Provide security functions of this layer; (2) Manage channel access; (3) Use CSMA-CA channel access; (4) Synchronize the device with the beacon (in the network using the beacon); ( 5) Generate beacons (coordinator only); (6) Provide disassociation and association functions in the network; (7) Establish reliable links between peer devices.3.4 Physical layerThe physical layer is the lowest layer of the protocol stack, which is closest to the hardware. The main functions of the physical layer include: directly transmitting data; selecting a communication channel; listening to the channel to determine whether it is idle; detecting signal energy; controlling the switch of the wireless transceiver; detecting link quality; data modulation and resolution Tune. The physical layer also provides management services and data services. The management service is to manage the relevant data of this layer through the database; the data service is to encapsulate and send data packets or receive and analyze data packets when communicating with other ZigBee devices.4. ZigBee data transmission methodZigBee equipment can use the channel in two ways: contention or no contention. In the competition mode, all devices in the network use the CSMA-CA mechanism to send messages, and the first to find an idle channel transmits data first. In the non-contention mode, the PAN coordinator allocates time for other devices to send messages, that is, guaranteed time slots. The device does not need to listen to the idle state of the channel to send data during the guaranteed time slot. The coordinator keeps devices in the network synchronized through beacons, providing guaranteed time slots. There are three ways of data transmission in IEEE802.15.4: (1) from peer device to peer device; (2) from device to coordinator; (3) from coordinator to device.4.1 Data transfer between peer devicesIn a peer-to-peer network all devices are usually synchronized and any device can communicate with each other. In a mesh network, there are multiple optional routes for data from the sender to the receiver. If the original route cannot be used due to environmental changes, the devices in the network cooperate to find an alternative route. This ability to dynamically create and modify routes increases the reliability of data transfers.4.2 Data is sent to the coordinatorIn a beacon-enabled network, devices periodically synchronize their clocks via beacons. If it is not in the guaranteed time slot, the device uses the CSMA-CA method to send data to the coordinator. The timing diagram is shown in Figure 3-3(a). Figure 3-3(b) shows the process of data being sent to the coordinator in a network without beacons enabled, and the device will send data as soon as it detects that the channel is free. Only when the device needs it, the coordinator will reply with an acknowledgment message to indicate receipt of the data.4.3 Send data from the coordinatorFigure 3-4(a) illustrates the process of sending data from a coordinator to a receiving device in a beacon-enabled network. First, the coordinator will remind the receiving device that there is data to be transmitted in the beacon. After receiving the beacon, the receiving device sends a data request to the coordinator, indicating that it is ready to receive data. After receiving the data request message, the coordinator replies with an acknowledgment and sends the data to the target device. When the receiving device receives the data, it replies with an acknowledgment as needed.In a network that does not support beacons, the coordinator will cache data and wait for the receiving device to actively request data. If the coordinator has no data cache, it sends a data message with a specially formatted acknowledgment reply or a zero-length payload, indicating that there is no data to send.The above are the details of ZigBee wireless communication technology introduced by Shenzhen Zuchuang Microelectronics Co., Ltd. for you. If you have Bluetooth product design and development needs, you can trust us. We have rich experience in custom development of smart electronic products. We can evaluate the development cycle and IC price as soon as possible, and can also calculate the PCBA quotation. We are a number of chip agents at home and abroad: Songhan, Yingguang, Jieli, Ankai, Quanzhi, realtek, with MCU, voice IC, BLE Bluetooth IC, dual-mode Bluetooth module, wifi module. We have hardware design and software development capabilities. Covering circuit design, PCB design, single-chip microcomputer development, software custom development, APP custom development, WeChat official account development, voice recognition technology, Bluetooth development, wifi technology, etc. It can also undertake the research and development of smart electronic products, the design of household appliances, the development of beauty equipment, the development of Internet of Things applications, the design of smart home solutions, the development of TWS earphones, the development of Bluetooth earphone speakers, the development of children's toys, and the research and development of electronic education products.
06-17

2023

Bluetooth topology networking

Bluetooth topology networking technology solutionDeepening teaching reform and making teaching more interactive is one of the important goals of the development of educational technology, and it is also the embodiment of the value of modern technology in educational reform. On the one hand, in the traditional teaching, the class teaching system is used to divide students, and there are differences in the level of students, so it is difficult to meet the requirements of teaching students in accordance with their aptitude.On the other hand, the traditional teaching mode separates the knowledge content from the real and rich situational relationship it produces, resulting in subjective passive learning and stagnant knowledge, which is not conducive to effectively building a complete knowledge system and innovation. Traditional education adopts the cramming education method, and students cannot obtain perceptual and diversified learning modes, and the interaction between teachers and students, and between students and students is very poor. Therefore, attention should be paid to the improvement of experimental methods and technologies, and new educational models such as interactive education, independent choice of courses and learning environments should be widely adopted and accepted. The combination of wireless network education and traditional campus network shows people a brand-new and broad learning level, breaking through the shackles of traditional education methods, as long as there is a digital terminal and equipment connected to the network, learning can be carried out anytime and anywhere and training. The bluetooth technology that appears in the field of wireless communication can transmit data such as voice, image and text synchronously, and is an effective technology for realizing wireless network education.Bluetooth (Bluetooth) is a short-range wireless communication technology standard jointly formulated by five companies including Ericsson, IBM, Intel, Nokia, and Toshiba in 1995. Its purpose is to achieve a maximum data transmission rate of 1Mb/s and a maximum transmission distance of 10m. Wireless communication. The Bluetooth operating frequency is the 2.4GHz ISM (Industrial, Scientific, Medical) frequency band commonly used in the world, so there is no need to apply for an applicable license from the Federal Communications Commission (Federal Communication Commission) or any international regulatory agency. Bluetooth products communicate with the Internet, so that devices between classrooms and offices, and between student data terminals and campus networks can be interconnected without cables, greatly improving office and communication efficiency.1. Introduction to Bluetooth TechnologyBluetooth is an open low-cost, short-range wireless connection technology specification for transmitting voice, image and text data between different devices. As a standard for short-range wireless interconnection between fixed electronic devices and portable electronic devices, Bluetooth replaces cable connections. Its main features are stable work, simple equipment, low power, little harm to the human body, and low price. Bluetooth technology is mainly oriented to various voice and data devices in wireless networks. It connects them into a piconet by means of wireless communication, and multiple piconets can also be interconnected into a distributed network, so that various devices can be realized conveniently and quickly. communication between. A communication device with Bluetooth function can establish a connection within a certain distance, thereby establishing a temporary personal wireless network. The Bluetooth technology wireless transceiver is a very small chip, about 9mm×9mm, which can be easily embedded into any fixed or portable device, easy to install, does not affect the appearance of the device, and has high practicability and operability. Bluetooth technology supports point-to-point and point-to-multiple communications. The principle of implementation is that a Bluetooth device relies on a dedicated Bluetooth chip to send radio signals within a short distance to find another Bluetooth device. Once found, the device starts to communicate.The characteristics of Bluetooth technology mainly include: ①The short-range Bluetooth wireless communication distance is 10m, which saves battery power; ②The wireless transceiver chip with low power, small size and low cost is only 0.5 square inches; ③Use simple link layer protocol and binary The frequency hopping technology further reduces the complexity and cost of the radio frequency chip; ④Bluetooth technology provides a standard rate of 1Mbit/s for the piconet; ⑤Using an additional power amplifier can extend the wireless communication distance to 100m. Within a Bluetooth range, multiple independent piconets can exist. These piconets form a distributed network so that more Bluetooth devices can be activated and combine to provide higher bandwidth.2.The structural characteristics of the Bluetooth technology systemLike OSI (Open System Interconnection), a layered approach is used in the protocol architecture of the Bluetooth technology standard, and its purpose is also to make applications interoperable. If the application programs of the remote device run on the same protocol stack, they can communicate with each other, and different application programs can use different protocol stacks. The Bluetooth protocol stack uses the common Bluetooth data link layer and physical layer protocols.The Bluetooth core protocol is a protocol unique to the Bluetooth technology standard, developed by the SIG (Bluetooth Special Interest Group). Bluetooth devices must support the Bluetooth wireless interface and core protocol, while other protocols can be selected according to specific circumstances, mainly including Logical Link Control and Adaptation Protocol (L2CAP), Service Discovery Protocol (SDP), and baseband protocol and link Management Protocol (LMP).(1) Baseband protocol. It is mainly responsible for establishing the physical radio frequency link between each bluetooth device unit in the micro network, that is, controlling the synchronization and transmission of the frequency hopping sequence. Because the Bluetooth radio frequency system uses frequency hopping spread spectrum technology, that is, frequency hopping is performed at a rate of 1600 hops/second on the 2.4GHz frequency band to realize information transmission and reception. A packet is meant to be sent at a specified time and at a specified frequency. The frequency hopping technology mainly divides the frequency band into several frequency hopping channels. On this layer, the clocks and transmission hopping frequencies of different Bluetooth devices are synchronized through paging and inquiry processes.(2) Link Management Protocol (LMP). It is mainly responsible for the control and establishment of the link between Bluetooth devices, as well as the negotiation and control of the size of the baseband group. It is mainly responsible for the completion of device link quality management, device power management, data packet management, link control management and link security management, etc. five tasks. It conducts authentication and encryption through connection initiation, exchange and verification, and determines the baseband data packet size through negotiation. The user of the device with Bluetooth function can set and control the link status of the remote Bluetooth device and the local Bluetooth device through the link manager, and then realize the management of the link.(3) Logical Link Control and Adaptation Protocol (L2CAP). The logical link control and adaptation protocol supports secondary multiplexing of high-level protocols, reassembly and segmentation of packets, and quality of service. It belongs to the underlying Bluetooth transmission protocol, which mainly focuses on the realization of wireless communication of data and voice data on the physical link. It is an adaptation protocol that shields the baseband protocol for the high-level transport layer and application layer protocols. The protocol allows high-level protocols and applications to send and receive data as long as 64K bytes. The Logical Link Control and Adaptation Protocol only supports asynchronous connectionless (ACL) links.(4) Service Discovery Protocol (SDP). The service discovery protocol plays a very critical role in the Bluetooth technology framework and is the basis of all user models. In the Bluetooth device network environment, the discovery of local devices and the use of services and functions provided by remote devices to provide their own services to other Bluetooth devices are also the main way of network resource sharing and the problem that SDP needs to solve. Device information, service characteristics and service types can be queried through the service discovery protocol. Users can select one of the available proximity services to establish a connection between two or more Bluetooth devices.Bluetooth supports packet switching and circuit switching technologies, and defines two types of links, namely connectionless asynchronous link (ACL) and connection-oriented synchronous link (SCO). Each link supports 16 different packet types, 4 of which are used for control packets.3. Application of Bluetooth network topology in modern universitiesThe modern university network designed based on Bluetooth technology must first solve the division of the network structure, so choosing an appropriate network topology has become the key to setting the network structure. Devices in the network are generally divided into master devices and slave devices. The clock and frequency hopping sequence of the master device are used to synchronize all other devices, namely slave devices. The device that performs paging and establishes a connection is defaulted as the master device connected to the network, and the device in the network that is synchronized with the clock and frequency hopping sequence of the master device is the slave device. Since the Bluetooth standard supports both point-to-point and point-to-multipoint connections, multi-networks can be established as required, and then multi-network connections can be made into a topology map of a scatternet.Due to the ease of use and high aggregation of the Bluetooth network, the wireless network structure of colleges and universities can be realized according to different network topologies. A typical Bluetooth-based wireless network takes the Internet network management center as the core, and the management center provides a wired network to each functional server. Users can access the corresponding server through the wireless access node of the server through digital terminal devices with Bluetooth functions such as smartphones, laptops, and PDAs. No matter when and where, as long as there is wireless network coverage, they can access the corresponding information.SummarizeAccording to different Bluetooth wireless network access methods, different wireless network-based solutions can be constructed. At present, point-to-point applications and wireless access points are mainly used. The construction of Bluetooth wireless network in colleges and universities is developed with the rapid development of computer network technology and modern communication technology. Wireless network is not a ban on wired network, but a functional expansion of it. Although there are problems in some technical details of Bluetooth, the integration of Bluetooth components, and the price, with the continuous development of technology, the application prospects of Bluetooth-based wireless networks in colleges and universities will be broader.The above are the details of the development of Bluetooth technology introduced by Shenzhen Zuchuang Microelectronics Co., Ltd. for you. If you have Bluetooth product design and development needs, you can trust us. We have rich experience in custom development of smart electronic products. We can evaluate the development cycle and IC price as soon as possible, and can also calculate the PCBA quotation. We are a number of chip agents at home and abroad: Songhan, Yingguang, Jieli, Ankai, Quanzhi, realtek, with MCU, voice IC, BLE Bluetooth IC, dual-mode Bluetooth module, wifi module. We have hardware design and software development capabilities. Covering circuit design, PCB design, single-chip microcomputer development, software custom development, APP custom development, WeChat official account development, voice recognition technology, Bluetooth development, wifi technology, etc. It can also undertake the research and development of smart electronic products, the design of household appliances, the development of beauty equipment, the development of Internet of Things applications, the design of smart home solutions, the development of TWS earphones, the development of Bluetooth earphone speakers, the development of children's toys, and the research and development of electronic education products.
06-16

2023

Car Bluetooth Technology Application

Bluetooth (Bluetooth) technology is actually a short-range wireless communication technology. Originally created by telecommunications giant Ericsson as an alternative to RS232 data lines. The use of "Bluetooth" technology can effectively simplify the communication between mobile terminal devices such as handheld computers, notebook computers and mobile phones, and can also successfully simplify the communication between these devices and the Internet, making the data transmission between these modern communication devices and the Internet become faster and more efficient. With the continuous development of technology, the performance stability and security of Bluetooth have also been greatly improved, and users can have a better experience. As the car is an important means of transportation for people, combining Bluetooth technology with the car system will bring great convenience to car production and car service. At present, Bluetooth technology has been widely used in vehicle application systems and network control and other fields, and it will be more widely and deeply used in the automotive field in the future.1. Application status of Bluetooth technology in automobilesThe wide application of Bluetooth technology in the field of automobiles stems from its own high-end technology, especially in the six fields of automobile hands-free communication, rearview mirror, Bluetooth entertainment system, Bluetooth self-diagnosis technology, Bluetooth anti-theft system and car steering wheel control system. aspect.(1) Bluetooth hands-free communication: Nowadays, many cars are equipped with car phones, mainly using the wireless communication technology function of Bluetooth. The car phone can automatically identify the user's mobile phone card, and make a detailed classification of the specific information in it, such as the user's address book, the ownership of the phone, and the phone's own number, and can automatically connect to the car network. These functions can make the user's mobile phone and the car phone communicate with each other in a wireless communication mode. When the user needs to answer or make a call during driving, he can directly use the car phone to communicate, which is also of great significance to the safety of driving.(2) Bluetooth rearview mirror: The Bluetooth rearview mirror of a car is similar to a new type of car phone display. It connects the rearview mirror of the car with the mobile phone through the wireless Bluetooth function, which makes it a cutting-edge vehicle communication device. At this time, the rearview mirror can display the incoming call number when answering the call, and automatically generate the hands-free function. The rearview mirror has a built-in battery that is powered by the car. This application increases the convenience of the user in the driving process, and the mobile phone number of the incoming call can be directly seen without using the mobile phone screen.(3) Car Bluetooth entertainment system: Nowadays, people have higher and higher demands on car performance, and hope to have multiple experiences during driving. Drivers often feel bored during car driving, and the Bluetooth entertainment system can play and display audio, video, etc. in the car through a wireless Bluetooth connection with the user's mobile phone. The car Bluetooth entertainment system is the most widely used navigation all-in-one machine, which adds the Bluetooth car function to the car's navigation device, so that the device not only has communication functions, but also makes it a reality to connect with smart phones. Greatly increase the entertainment of the driving process.(4) Vehicle-mounted Bluetooth self-diagnosis technology: Long-term driving will cause certain faults in the car, and some hidden faults cannot be discovered by the naked eye in time, which will bring great safety hazards to users. The Bluetooth self-diagnosis technology on the car can be sent to the user's mobile phone through wireless Bluetooth transmission, so that the driver can intuitively understand the performance of the car and the reasons for possible failures. Through a new type of data expression, a preliminary assessment is automatically made for the car to ensure the safety factor of driving. At the same time, the detection data of the Bluetooth self-diagnosis technology can also be sent to a professional car maintenance company through the user's mobile phone, and the professional maintenance technicians will conduct a comprehensive evaluation to eliminate possible safety hazards, so that some novice drivers can rest assured Travel by car.(5) Car Bluetooth anti-theft system: How to effectively prevent theft while increasing the convenience of using the anti-theft system when parking has become the focus of the current automotive field. The Bluetooth anti-theft system used today is mainly to wirelessly connect the mobile phone to the Bluetooth of the car, and then use special software to lock and unlock the car door. The anti-theft of the engine is mainly realized by the on-off control of the engine starting circuit by the on-board Bluetooth. The engine can start normally only when the car Bluetooth can be connected to the previously matched mobile phone Bluetooth. Once the Bluetooth of the mobile phone exceeds the connection range of the Bluetooth of the car, the engine of the car will be in a state of being unable to start. For the anti-theft of the car door and engine, two Bluetooth anti-theft systems are used, and these two systems can use two different authentication passwords to increase the safety factor of use.(6) Automobile steering wheel control system: With the continuous rapid development of science and technology, the automobile steering wheel is also developing in the direction of intelligence. More and more automobile steering wheels also realize the control of related operations of the automobile steering wheel panel through Bluetooth data transmission . The cost of this automobile steering wheel control system is relatively low, and at the same time, it has good stability and high safety factor.2. The development trend of Bluetooth technology in automobilesToday, Bluetooth technology has been widely used in people's lives, and its application in automobiles is a powerful proof. It makes car driving more and more convenient, intelligent and humanized, becoming an irresistible social trend in the future. At the same time, in the future development of the automotive industry, Bluetooth technology should give full play to its own special advantages to improve its application level and high-quality data transmission. Next, the wheel force transmission system and the vehicle operating condition recording system are mainly summarized.(1) Wheel force transmission system: The wheel force transmission system requires high-precision standards, and Bluetooth wireless technology can improve the accuracy of data collected by the wheel force sensor during data transmission. The force of the car during driving is multi-directional and multi-dimensional. How to collect these forces well is of great significance to the performance evaluation of the vehicle. In this way, professional evaluation personnel can understand the performance coefficient of various aspects of the vehicle during dynamic driving.(2) Vehicle operating condition recording system: The operating condition of the vehicle is a powerful data for the safety of the vehicle as a whole. Bluetooth technology can effectively obtain accurate data through the acquisition equipment in the car device. Among them, the data transceiver chip has many advantages such as easy installation and carrying, and high accuracy of data transmission at the same time. The data collected wirelessly by Bluetooth technology is more convenient for centralized processing and control.3. Problems and Countermeasures of Bluetooth TechnologyAlthough bluetooth technology can bring great convenience in the driving process, it also has many problems that people still need to solve. Bluetooth technology is everywhere in our life, but many people still have a little understanding of Bluetooth technology, lack of security knowledge related to Bluetooth technology, resulting in a series of problems. The two relatively serious problems of Bluetooth hijacking and Bluetooth eavesdropping are mainly described below.Bluetooth hijacking means that users send business card information anonymously through Bluetooth-related technologies. This approach will not cause mobile phones and other devices to delete or directly change related information, but it may transmit some important private data through Bluetooth, or import some useless spam information from the outside world to mobile phones and other devices . Bluetooth eavesdropping refers to a method where the outside world directly accesses the mobile phone without reminding the device user, so that outsiders can directly obtain important private data through the mobile phone, and even modify relevant information through Bluetooth technology. The well-known Bluetooth eavesdropping technology is to monitor private calls, which will bring great security and privacy problems to users.The main measures taken for these two problems: the manufacturers of related equipment should strengthen the safety factors in all aspects through hardware. At the same time, professional software companies also need to develop and upgrade specific security software to reduce this major hidden danger from a technical perspective. Users should also pay attention to safety issues during operation. For example, when not using Bluetooth technology in daily life, or in some unknown places that are not sure whether it is safe or not, you can set mobile phones and other devices to non-discoverable mode, or set them not to communicate with Bluetooth technology. Unknown device pairing mode.epilogueAt present, Bluetooth technology is still in the development stage, and it also has many problems while bringing convenience to people's life. Widely used in automobiles, when Bluetooth technology brings convenient applications such as hands-free communication and Bluetooth rearview mirrors to users, it also brings certain privacy and security issues. Nowadays, the price of domestic Bluetooth chips is relatively high, and production is more difficult. But with the development of national high-tech, bluetooth technology will definitely bring new changes.The above are the details of the application of Bluetooth technology in automobiles introduced by Shenzhen Zuchuang Microelectronics Co., Ltd. for you. If you have Bluetooth product design and development needs, you can trust us. We have rich experience in custom development of smart electronic products. We can evaluate the development cycle and IC price as soon as possible, and can also calculate the PCBA quotation. We are a number of chip agents at home and abroad: Songhan, Yingguang, Jieli, Ankai, Quanzhi, realtek, with MCU, voice IC, BLE Bluetooth IC, dual-mode Bluetooth module, wifi module. We have hardware design and software development capabilities. Covering circuit design, PCB design, single-chip microcomputer development, software custom development, APP custom development, WeChat official account development, voice recognition technology, Bluetooth development, wifi technology, etc. It can also undertake the research and development of smart electronic products, the design of household appliances, the development of beauty equipment, the development of Internet of Things applications, the design of smart home solutions, the development of TWS earphones, the development of Bluetooth earphone speakers, the development of children's toys, and the research and development of electronic education products.
06-15

2023

Bluetooth dynamic multi-protocol technology

ZigBee Bluetooth dynamic multi-protocol technology1. Introduction to dynamic multi-protocol technologyZigBee/Bluetooth dynamic multi-protocol technology is a technology proposed by Silicon Labs that can run two different protocols of low-power Bluetooth and ZigBee concurrently on a single system chip. This technology combines the main advantages of the two protocols, can complete the main functions of the two protocol stacks, and does not increase the structural complexity and cost of the hardware. Compared with the dual-chip structure with the same function, the dynamic multi-protocol reduces the chip area and cost by nearly 40% by sharing the radio frequency module. In a chip that supports dynamic multi-protocol technology, the software system kernel running in it runs ZigBee tasks and Bluetooth tasks in time based on priority, and quickly modifies the configuration parameters of the radio frequency module when switching tasks, so as to reliably support different protocol stacks. The system also listens to all system-related tasks and inter-task communications while running each task. Therefore, an efficient dynamic multiprotocol system requires a radio scheduler capable of supporting task switching, resource sharing, and managing time slicing, in addition to having a common code infrastructure, sufficient memory, and a common radio interface.2. The principle of dynamic multi-protocol technology2.1 Dynamic multi-protocol system framework(1) Hardware architecture: The hardware framework of the dynamic multi-protocol system is shown in Figure 3-10. RAIL (Radio Abstraction Interface Layer, wireless abstraction interface layer) provides an intuitive and easy-to-configure radio interface and application programming interface (API) to support Various wireless protocols.RAIL includes a public radio configuration interface and radio scheduler, supporting dynamic multi-protocol operation. The radio scheduler assigns default priorities to the different radio operations in each protocol based on importance and time sensitivity to make decisions when radio usage conflicts. The difference in the characteristics of the two protocols can be utilized in dynamic multi-protocol design. The radio usage schedule in the Bluetooth Low Energy mission is very strict and predictable, with both advertisements and connections occurring at predetermined times. In contrast, ZigBee tasks are more flexible in the timing of processing message events, and CSMA-CA in ZigBee has a random dodging mechanism that can delay ZigBee events for several milliseconds. The data packets of Bluetooth beacons are very short, no more than 30 bytes, and only take up about 1ms of radio time when sending. The time between beacons is typically no shorter than 100ms, so Bluetooth only has about a 1% duty cycle in radio use, which means the radio can be used for the main ZigBee network the other 99% of the time. Therefore, it can be ensured that ZigBee can be used to reliably send and receive data while using Bluetooth low energy normally.(2) Software architecture: As shown in Figure 3-11, in the dynamic multi-protocol system, each stack uses the Micrium OS kernel to run a separate RTOS task to provide task switching, and the tasks are equivalent to threads in other operating systems. These tasks use inter-process communication (IPC) mechanisms such as message queues and semaphores to coordinate mutual communication and realize data sharing.2.2 Dynamic Multiprotocol Radio SchedulingSince two different protocols cannot rely on a single radio transceiver to send and receive data at the same time, in order to achieve dual protocols, the two protocols can only share the use of radio transceivers. In order not to impact the functionality of either protocol, they must be able to take the radio out of use intermittently without significant performance degradation or loss of data. In different cases, the different radio operations in the two protocols are not as important or time-sensitive, which requires the use of radio scheduling to plan radio usage.The radio scheduler is a software program that intelligently responds to stack requests to perform radio operations, maximizing reliability and minimizing latency. Each event is broken down into radio operations in the scheduler, corresponding to the radio configuration and priority. If the scheduler receives a higher-priority operation that conflicts in time, it will interrupt the current operation and execute the higher-priority operation, and lower-priority operations that cannot run according to the schedule will fail and be retried by the stack. Once the scheduler starts performing a radio operation, the stack can continue to use the radio until the operation completes or the scheduler receives a higher priority radio operation. BLE radio operations will almost always have higher priority than ZigBee radio operations.Each stack can request the radio scheduler to perform three radio operations: (1) background receive: receive data continuously unless interrupted by other tasks; (2) timed receive: receive data at a future point in time with the shortest possible time; ( 3) Timing sending: send data in the shortest time at a certain point in the future.Each operation has a start time, reserve time, processing time, and priority. Among them, the start time indicates when the radio operation will take place, the reserved time indicates the time when the operation uses the radio and can be accepted by the stack, and the processing time indicates the approximate time required to complete the operation. A send operation usually has a definite processing time, while a receive operation usually has an unknown processing time, which is used by the radio scheduler to determine whether to allow the operation.3. Advantages of dynamic multi-protocol technologyDynamic multi-protocol technology switches and runs different protocols through time multiplexing, and the way of sharing radio transceivers simplifies system design and reduces material costs. By combining the two protocols, Dynamic Multi-Protocol has the key advantages of ZigBee and Bluetooth.Compared with ZigBee technology, dynamic multi-protocol technology has the following advantages: (1) supports direct configuration and control based on smartphones; (2) provides diagnostic functions, and can check the health status of devices through smartphones; (3) can pass Bluetooth performs high-speed OTA upgrade of firmware; (4) supports positioning function.Compared with Bluetooth technology, dynamic multi-protocol technology has the following advantages: (1) ZigBee-side networking is more flexible and simple; (2) ZigBee mesh network with routing method has larger capacity, while BLE Mesh adopts large data flow Flooding, greater network load and poorer scalability; (3) ZigBee devices that comply with the specification have excellent interoperability, while Bluetooth interoperability requires manual modification of the Bluetooth connection settings.Compared with the traditional dual-chip supported dual-protocol (such as ZigBee/Bluetooth gateway), dynamic multi-protocol has the following advantages: (1) By sharing the RF module, the size and material cost are reduced by nearly 40% and the wireless subsystem design is simplified; (2) Dynamic multi-protocol uses time-division multiplexing to reduce signal interference between Bluetooth and ZigBee working in the same frequency band. To sum up, it can be seen that dynamic multi-protocol has obvious advantages over single protocol and dual-chip supported dual-protocol. It not only makes full use of the respective strengths of Bluetooth and ZigBee, but also saves costs and enhances scalability. Therefore, this paper uses dynamic multi-protocol technology at the control center, and uses ZigBee technology as the main communication method between system nodes.This article discusses ZigBee/Bluetooth dynamic multi-protocol technology, explains its working principle, and analyzes the advantages of dynamic multi-protocol technology compared to single protocol and traditional dual-chip dual-protocol.
06-14

2023

Design of Temperature and Humidity Acquisition System

Design and Analysis of Wireless Temperature and Humidity Acquisition System Based on BluetoothAt present, in the existing temperature and humidity data acquisition system, the temperature and humidity data collected by the sensor are transmitted to the host computer through a wired serial port (RS-232 or RS-485) with strong anti-interference ability and mature technology. If there are many collection points, a large number of data lines are required for wired connection between the sensor and the host computer. This way of wired connection will cause great inconvenience; if it is necessary to establish temporary temperature and humidity data collection, use traditional The wired connection method will increase the cost; at the same time, the wired connection method will cause great inconvenience to the construction in harsh environments. Therefore, a low-cost, high-stability wireless data transmission method is required to replace the existing wired data transmission method.Wireless communication communicates by radiating and receiving electromagnetic waves in an open space. On the one hand, it is more seriously affected by various interference and noise in nature than wired; on the other hand, wireless communication signals within a certain area will also interfere with each other. In order to overcome the interference between wireless communication signals, the available wireless channel must be divided into several independent sub-channels and assigned to each user respectively. Although compared with wired communication, wireless communication has great deficiencies in terms of transmission quality and transmission rate, but wireless communication has the advantages of being free from connection constraints, fast and flexible networking, etc., especially providing mobile communication, making wireless communication technology Become the most active field of communication technology research.As a low-cost, low-power, short-range wireless communication technology, Bluetooth is widely used in communication between fixed equipment and mobile equipment.Bluetooth data transmission rate can be as high as 1Mb/s, using frequency hopping/time division multiplexing technology, with one-to-one and one-to-many communication methods. Therefore, this paper proposes a bluetooth-based wireless temperature and humidity acquisition system design and analysis scheme.1. Structural Design of Temperature and Humidity Acquisition SystemData acquisition is an indispensable and important part of industrial systems and the fundamental basis for industrial control. With the development of science and technology, large-scale integrated circuits, single-chip microcomputers, computers, etc. are widely used in the field of industrial control, making digital data acquisition inevitable in the field of industrial control. This design consists of the data acquisition and data transmission part of the lower computer and the data reception and data processing part of the upper computer. Figure 1 shows the system structure diagram. The lower computer is mainly composed of a single-chip microcomputer and a Bluetooth module, and the data acquisition is mainly a DHT11 temperature and humidity sensor; the data transmission part mainly performs wireless data transmission through the Bluetooth module, and transmits the data to the upper computer through the Bluetooth module, and is processed by the upper computer. 2. Hardware design of temperature and humidity acquisition systemIn this design, Arduino single-chip microcomputer is used as the main control single-chip microcomputer of the lower computer. The hardware design of the system is mainly divided into three parts: Arduino microcontroller control part, DHT11 temperature and humidity sensor, Bluetooth wireless communication module. Arduino MCU has rich interfaces, including digital I/O port and analog I/O port, and it supports SPI, IIC, UART and other communication methods. Various types of sensors can be connected externally to control various devices such as lights and motors. Arduino single-chip microcomputer has no complicated underlying code compared with ordinary single-chip microcomputers, and has rich library functions. Different functions can be realized by calling different library functions, and it has the characteristics of convenient programming. Moreover, it has a special set programming download environment IDE, which facilitates the secondary development of Arduino single-chip microcomputer by developers.2.1 DHT11 sensorThe temperature and humidity are measured by DHT11 temperature and humidity sensor. The measured temperature accuracy reaches ±5%RH, the temperature is ±2°C, the measured humidity range is 20-90%RH, and the temperature range is 0～+50°C. DHT11 temperature and humidity sensor is a composite sensor with digital signal output. The DHT11 temperature and humidity sensor contains a resistive humidity sensing element and an NTC temperature measuring element, and is connected with a high-performance 8-bit microcontroller. At the same time, the sensor has a single-wire serial interface, and the temperature and humidity information collected by the sensor can be transmitted to the Arduino microcontroller through the single-wire serial interface.Since the data transmission between the DHT11 sensor and the Arduino microcontroller is through the single-line serial interface, in order to ensure the integrity of the data, the communication time is set at about 4ms, and the data is divided into two parts: a fractional part and an integer part. A complete data transmission It is 40bit, high bit first out.Data format: 8bit humidity integer data + 8bit humidity decimal data + 8bit temperature integer data + 8bit temperature decimal data + 8bit checksum data When the data transmission is correct, the checksum data is equal to "8bit humidity integer data + 8bit humidity decimal data + 8bit temperature integer data + 8bit temperature decimal data" The last 8 digits of the result. When the Arduino microcontroller sends a start signal to the DHT11 sensor, the sensor immediately changes from the low-power standby mode to the working mode, and the DHT11 sensor sends a response signal to the microcontroller, sending out 40bit temperature and humidity data.2.2 Bluetooth communication moduleThis design application is the HC-05 bluetooth module that adopts BlueCore4-Ext chip of British CSR Company. The module supports UART, USB, SPI, PCM, SPDIF and other interfaces, and supports SPP Bluetooth serial port protocol. It has the function of master-slave integration, built-in PCB RF antenna, and can connect 7 slave devices. At the same time, the working voltage of the module is 3. 3-6V, so this module has the advantages of low cost, small size, low power consumption, and high sensitivity of sending and receiving.Because the HC-05 Bluetooth module has two working modes: command response working mode and automatic connection working mode. In the automatic connection working mode, the module can be divided into three working roles: Master, Slave and Loopback. When the module is in the automatic connection working mode, it will automatically transmit the data connected according to the preset method; when the module is in the command response working mode, it can execute AT operation commands, and can send AT commands to the module through the computer to set the control for the module. parameters or issue control commands. The conversion of the working state of the module can be realized by controlling the input level of the external pin of the module.3. Software Design of Temperature and Humidity Acquisition SystemIn order to ensure the readability and succinctness of the program, the Arduino single-chip programming adopts C language for programming. The Arduino microcontroller adopts a timing method for data reception, that is, it sends sampling signals to the DHT11 temperature and humidity sensor every 1 second, and at the same time, the DHT11 transmits the collected data to the microcontroller through the single-line serial port interface, and then stores the data in the internal memory of the microcontroller. Wait for the Bluetooth module to send wirelessly.The Bluetooth module connected to the Arduino microcontroller takes out the data in the internal memory of the microcontroller through the serial port, and then sends the temperature and humidity data to the host computer according to the set communication method.3.1 PC software designThe upper computer system is written in C# language, which is widely used in graphic programming. C# is a safe, stable and simple programming language. It is an object-oriented programming language derived from C and C++. It inherits the functionality of C and C++ while stripping away their complexity. At the same time, the C# programming language combines the visual graphical interface of the VB programming language and the high operating efficiency of the C++ language. First, the system initializes, establishes a Bluetooth connection, and re-establishes the connection if the connection fails. After the connection is successful, data reception starts. If the data cannot be received or the data reception fails, the data reception will be restarted until the data can be successfully received.Since the information transmitted to the upper computer through the Bluetooth wireless module is for data communication with the serial port, the receiving serial port number, baud rate, parity bit, data bit and stop bit must be set in the upper computer. Click to start receiving and the system will automatically receive information every 5 seconds. If manual collection is required, you can directly click manual collection to switch between automatic and manual. The collected information will be displayed in the right box, and the formats are time, temperature, and humidity.If you need to save the collected data for later analysis and sorting, you can click Save Data, and the system will automatically save the data as a file in TXT format.SummarizeThis paper mainly designs and implements a Bluetooth-based wireless temperature and humidity acquisition system. Through Bluetooth wireless communication, the collected data is sent to the host computer acquisition system, and the acquisition system is responsible for receiving, processing, information extraction and storage of data. Considering the characteristics of communication in practical applications, the communication method in this paper adopts the combination of Bluetooth wireless communication and serial port communication. The establishment and implementation of bluetooth communication and the implementation of serial communication are briefly introduced respectively. The upper computer software design adopts C# language for programming to realize the system initialization, establish bluetooth communication, data receiving and other process management. The experimental results show that the hardware design of the system is reliable and practical, and the software design is simple and convenient for secondary development, which can meet the data acquisition and communication requirements in different situations.The above is the design and analysis of the Bluetooth-based wireless temperature and humidity acquisition system introduced by Shenzhen Zuchuang Microelectronics Co., Ltd. If you have Bluetooth product design and development needs, you can trust us. We have rich experience in custom development of smart electronic products. We can evaluate the development cycle and IC price as soon as possible, and can also calculate the PCBA quotation. We are a number of chip agents at home and abroad: Songhan, Yingguang, Jieli, Ankai, Quanzhi, realtek, with MCU, voice IC, BLE Bluetooth IC, dual-mode Bluetooth module, wifi module. We have hardware design and software development capabilities. Covering circuit design, PCB design, single-chip microcomputer development, software custom development, APP custom development, WeChat official account development, voice recognition technology, Bluetooth development, wifi technology, etc. It can also undertake the research and development of smart electronic products, the design of household appliances, the development of beauty equipment, the development of Internet of Things applications, the design of smart home solutions, the development of TWS earphones, the development of Bluetooth earphone speakers, the development of children's toys, and the research and development of electronic education products.

Home Prev 1 2 3 4 Next Last

TOP