Design and development of intelligent greenhouse system

The modern greenhouse automatic control system can measure agricultural environmental factors such as wind speed, wind direction, humidity, temperature, light, air pressure, rainfall, solar ultraviolet rays, solar radiation, soil temperature and humidity, and automatically control window opening, roll film, Environmental control equipment such as fan wet curtain, biological supplementary light, irrigation and fertilization, etc., can automatically adjust the environment in the greenhouse to reach the range suitable for plant growth and provide the best environment for plant growth.

Greenhouse refers to the season that is not suitable for plant growth, which can provide the temperature, humidity, carbon dioxide and water required for plant growth, thereby increasing the output of fruits and vegetables.

a. Temperature factor: Plants can only grow within a certain temperature range. It can affect metabolic processes such as photosynthesis, respiration, and transpiration. It can also affect the growth of plants by affecting metabolic processes such as the synthesis and transportation of organic matter. It can also directly It affects the soil temperature and air temperature, and affects the growth of plants by affecting the absorption and transportation of water and fertilizer. Since the activities of enzymes involved in metabolic activities have different performances at different temperatures, the influence of temperature on plant growth also has three basic points: minimum, optimum and maximum temperature. Plants can only grow within the range of the minimum temperature and the maximum temperature. If At the optimum temperature, the organic matter in the plant is consumed too much, and the plant grows slender and weak.

b. Humidity factor: The air humidity affects the opening and closing of plant stomata. Too high or too low air humidity will cause the stomata to close, and the plant stomata will close. CO2 cannot enter the mesophyll cells, and photosynthesis will slow down or even stop. Excessive humidity is conducive to the reproduction of germs. The germination of most fungal spores and the development of mycelium require high humidity. Too low humidity is conducive to the occurrence of insect pests. For example, the occurrence of mites such as spider mites generally occurs in high temperature and low humidity environments. .

c. Carbon dioxide factor: CO2 is an essential substance for photosynthesis. Photosynthesis is the most basic material metabolism and energy metabolism in the biological world. The life activities of all organisms directly or indirectly depend on the organic matter produced by photosynthesis and fixed solar energy. Respiration is divided into aerobic respiration and anaerobic respiration. Anaerobic respiration produces alcohol or lactic acid, and aerobic respiration produces CO2 and H2O, both of which release energy. The photosynthesis of plants provides the material basis for respiration, and respiration provides energy and raw materials for photosynthesis. They are two interdependent and opposite processes, and they are in a unity. There is no organic compound synthesized by photosynthesis. , it is impossible to have organic matter decomposed by respiration and oxygen reaction, without the O2 released by photosynthesis, it is impossible to have enough O2 in the air to continuously supply biological respiration. Without the energy released by respiration, photosynthesis cannot proceed , and the CO2 released by respiration is also one of the raw materials for photosynthesis.

d. Water factor: Plants have different requirements for water at different stages of plant growth. For example, tomatoes and peppers need enough water to replenish plants in the seedling stage, and a small amount of water is needed after fruiting. If the water is too large The fruit will rot after the result, so the amount of water plays a vital role in plant growth and cannot be ignored.

1. The composition of the intelligent greenhouse system architecture

The intelligent greenhouse system is divided into three parts: data acquisition part, data transmission part and control part.

1.1 Data collection part

(1) Temperature sensor: The sensor is composed of 3 modules: a. Temperature sensor module with an accuracy level of ±0.5°C; b. Single-chip microcomputer system module; c. Wireless transmission module; d. Ultra-long standby battery.

(2) Humidity sensor: The sensor is composed of 3 modules: a. Humidity sensor module, using the SHT11 analog head imported from the United States, with an accuracy level of 3% RH; b. Single-chip system module; c. Wireless transmission module; d. Long standby battery.

After the temperature and humidity sensor module detects the on-site temperature data, the data is processed by the single-chip microcomputer, and the single-chip microcomputer directly processes the digital signal received from the sensor, and finally drives the wireless transmission module to send the data wirelessly. Each sensor has an ID number, and this ID number is composed of 24 letters and numbers, which can realize unlimited serial number combinations, and can realize a globally unique ID number; the ID number of each tag and its location are Correspondingly, when the system builds the database, the location can be bound to the information of the ID number. That is to say, when the system reads the ID number of "1234567", the system will know that the tag is in: which greenhouse? Which position segment? If the data measured by the tag is higher, the system will know the specific location. Location. The transmission distance of this wireless temperature sensor can reach 120 meters.

(3) CO2 sensor: The sensor adopts the form of infrared spectrum, and the range of 0-2000PPM can meet all the needs of plant research. The sensor is not sensitive to high temperature and high humidity in scientific research greenhouses.

(4) Rainfall sensing sensor: mainly used to detect whether there is rainfall. This product can judge different situations of rainfall and condensation, and has the characteristics of reliable operation and low price.

(5) Soil moisture sensor: The sensor certified by the Ministry of Water Resources is adopted. The sensor adopts the advanced "time domain reflection principle", rod-type design, and the sensing part is 48cm. It is suitable for measuring the volumetric moisture content of any type of soil, with accurate measurement and stable and reliable performance. .

(6) Plumbing water temperature sensor and soil temperature sensor: good consistency, high precision, and good sealing.

(7) Liquid surface humidity sensor: It mainly measures the degree of leaf evaporation on the surface of plants and the humidity on the surface of plants, suitable for high-end flowers. Example: poinsettia, this series of sensors is suitable for measuring temperature and humidity in agriculture, gardening, meteorology, environmental protection and other fields. After insulating packaging and other processing techniques, it can work stably for a long time in harsh environments such as high temperature and high humidity.

(8) Rainfall sensor: The anti-bucket parts of this instrument are sensitive to turning, stable in performance and reliable in operation. The rain receiving port is made of stainless steel skin as a whole by punching and drawing, with high finish and small error caused by stagnant water. The shell of the instrument is made of stainless steel, which has strong anti-rust ability and good appearance quality.

(9) Wind speed and direction sensor: "Wind speed and direction sensor" is equipped with precision rotating moving parts inside. These mechanical parts have very good stability and can maintain the measurement accuracy of the sensor in harsh environments. The high-strength special engineering plastic shell has excellent Anti-UV aging effect.

Many types of sensors above can be directly placed in the greenhouse or outside the greenhouse. The most commonly used sensors are temperature sensors, humidity sensors, and light sensors. In this system, for these three sensors, we use wireless transmission methods and use wireless modules to send data to wireless routers. Other types of sensors are considered to be less used, and the cost of wireless transmission is higher, so they temporarily use wired data transmission. The sensor corresponds to its location, which can be bound to the information of the ID number when the system builds the database. That is to say, when the system reads the ID number of "1234567", the system will know that the tag is in: which greenhouse number? That segment? If the data measured by the tag is high, the system will know the specific location.

1.2 Data transmission part

Wireless router: read tags; microwave 2.4~2.5GHz microwave frequency band; hanging or fixed bracket installation, dustproof and waterproof, and the reading and writing distance from tags is 0~300 meters. When the signal of the wireless router covers the receiving range of the wireless sensor, the router can collect the data information from the tag; because the site needs to detect the environment in different locations, more sensors will be installed, and the data received by the router is redundant. Data fusion, organize multiple wireless sensor data into more accurate data, and wirelessly send it to the coordinator; besides receiving and sending wireless sensor data, the router can also be used as the upper router of other routers, and other routers can use this route to communicate with the coordinator. Coordinator of communications.

Wireless coordinator: read the repeater, receive the information transmitted by the repeater, and upload the data to the industrial computer through the serial port; the recognition distance is adjustable from 0 to 300 meters; the microwave frequency band is 2.4 to 2.5GHz; hanging or fixed bracket installation , Industrial RS485 serial port, dustproof and waterproof. The coordinator is the device that is finally connected to the computer. It collects routing data at the front end and transmits data to the computer at the back end. When the on-site data is larger and more, there will be no data congestion.

1.3 Control section

(1) Industrial computer: It adopts industrial PC with strong functions and performance, and has industrial-level serial communication and I/O port input and output. Built-in powerful software control functions: stable data acquisition, data analysis based on practical applications, expert database, and precise control logic.

(2) PLC control: Siemens S7 series PLC is used; multi-channel stable I/O control, industrial-level serial communication, and precise control timing.

(3) Drive control: motor, cylinder, solenoid valve.

(4) On-site execution unit: inner sunshade, outer sunshade, top opening window, side opening window, outer opening window of wet curtain, water pump of wet curtain, fan of wet curtain, 2 sets of fans, internal circulation fan, supplementary light, spray, micro Spray and other equipment.

2. The principle of intelligent greenhouse system

The four most important parameters in intelligent greenhouse environment control: air temperature, air humidity, soil temperature, and illuminance. According to the information collected by the temperature and humidity, soil moisture, soil temperature and other sensors in the greenhouse, it is connected to the upper computer for display, alarm and query. The monitoring center will display and store the sampled data received in the form of a table, and then compare it with the set alarm value. If the measured value exceeds the set range, an alarm will be displayed on the screen or a voice alarm, and the record will be printed.

2.1 Air temperature control

(1) On-site data collection: Multiple wireless sensors are placed in the greenhouse. Because the sensors send data wirelessly, there is no need to worry about complicated wiring. The sensors can be placed anywhere in the greenhouse and the position can be adjusted at will. The sensor also stores an ID number, and the ID of each sensor is globally unique and represents the identity of the sensor. After the sensor is placed, the sensor ID number, collected data, location and other information will be sent to the router together.

Generally, the day is divided into 4 time periods, namely, before noon, noon, the first half of the night and the second half of the night, for temperature adjustment. Before noon, it is mainly to promote photosynthesis and increase the amount of assimilation; in the afternoon, photosynthesis shows a downward trend; after sunset, it promotes the operation of assimilates in the body; at night, it suppresses respiration, reduces consumption, and increases accumulation; Set the cycle of sensor detection and outgoing data, you can set the cycle of sensor outgoing data to 1 time/hour, 1 time/minute, or 1 time/30 seconds, etc., firstly, it can be determined according to the actual needs of the site, secondly It can save power for the sensor and use it for a longer time.

(2) Data transmission: The sensor wirelessly sends the collected data to the indoor router, the router receives and converts the sensor data, the tag transmits the data in the form of electromagnetic waves, and the router demodulates the data after receiving it. At the same time, multiple tags will send data to the router, and the router will fuse the received data into more accurate data and send it out. For example: In addition to receiving and sending the data of wireless sensors, the router can also be used as the upper router of other routers, and other routers can use this route to communicate with the coordinator. The coordinator is the device that is finally connected to the computer. It collects routing data at the front end and transmits data to the computer at the back end.

(3) Control timing: A. The temperature is higher than the standard value: each plant has a different temperature growth curve, and plants will have different suitable growth temperatures in different time periods. For example, in each day, the temperature demand of plants There are 4 kinds, this is because they are in different time periods and have different transformation functions. When the air temperature in the greenhouse is higher than the standard value, the system will automatically compare the difference between the standard value and the actual value in a certain period of time, and then control different equipment to cool down. For example: when the sensor with the ID number "123456789" detects that the temperature data on site is 35.4°C, the data will be uploaded to the industrial computer through the wireless router and the wireless coordinator. In order to ensure that the temperature value is not an instantaneous value, the system will delay 0-90 seconds after receiving the data of the ID number for the first time, and then compare the values to accurately judge that the value is a trend value. The system will recall the standard value of 27°C during this period of time, and compare it with the on-site data. If it is judged that the temperature is 8.4°C higher than the on-site temperature, it will control the cooling device to turn on.

Control the opening sequence of the cooling equipment: when the system judges that the current temperature value cannot be reduced to the target value within a certain period of time (0-99 seconds adjustable), the cooling equipment will be opened sequentially; when the difference between the on-site temperature and the target temperature is large, the system will Control Jump to turn on one of the devices. Skylight: Open the top-opening window system in sections; adjust the temperature in the greenhouse through the outdoor natural greenhouse, and follow this principle until the top-opening window system is 100%. Side window: open the side window ventilation system in sections; follow this principle until the side window system is 100%. Forced cooling process: When natural ventilation cannot reduce the temperature in the greenhouse, the system automatically shuts down the related equipment of natural ventilation, and uses forced ventilation to control the indoor temperature. After a time delay, close the sunroof, followed by the side windows. Curtain-outward-turning window: open the wet-curtain-outward-turning window. One group of fans: Turn on the first group of fans. Wet curtain water pump: Turn on the wet curtain water pump. Second group of fans: Turn on the second group of fans. Circulation fan:

It is judged within a certain period of time that when the temperature in the greenhouse is not uniform, the circulation fan is turned on. Mist or Mist: Turn on the roof sprinkler system. Alarm: If it is judged that the temperature falls below the target value, the computer will turn on an over-temperature alarm, prompting the user to add cooling equipment. The system will constantly detect the on-site temperature, and when the on-site temperature tends to the target temperature, the system will shut down the cooling equipment.

B. The temperature is lower than the standard value: For example: when the sensor with the ID number "123456789" detects that the temperature data on site is 20°C, the line router and wireless coordinator will finally upload the data to the industrial computer. In order to ensure that the temperature value is not an instantaneous value, the system will delay 0-90 seconds after receiving the data of the ID number for the first time, and then compare the values to accurately judge that the value is a trend value. The system will call out the standard value of 27°C during this period of time, and compare it with the on-site data. If it is judged that the temperature is 7°C lower than the on-site temperature, it will control the heating device to turn on. Control the opening sequence of the heating equipment: when the system judges that the current temperature cannot be raised to the target value within a certain period of time (adjustable from 0 to 99 seconds), the heating equipment will be opened sequentially; Control Jump to turn on one of the devices. Inner sunshade insulation curtain: pull down the inner sunshade insulation curtain to prevent the indoor temperature from leaking out. External sunshade curtain: If the external light is strong, the external sunshade curtain can be opened to heat up through the light. Hot air stove, plumbing and air conditioning, heating: Turn on the heating device to increase the indoor temperature. Alarm: If it is judged that the temperature falls below the target value, the computer will turn on an over-temperature alarm, prompting the user to add cooling equipment. The system will constantly detect the on-site temperature, and when the on-site temperature tends to the target temperature, the system will shut down the heating equipment.

2.2 Air humidity control

(1) The humidity is higher than the standard value: For example, when the sensor with the ID number "123456789" detects that the humidity data on site is 80%RH, the data will be uploaded to the industrial computer through the wireless router and the wireless coordinator. In order to ensure that the humidity value is not an instantaneous value, the system will delay 0~90 seconds after receiving the data of the ID number for the first time, and then compare the values to accurately judge that the value is a trend value. The system will call out the standard value of 65%RH during this period and compare it with the field data. If it is judged that the temperature is 15%RH higher than the field temperature, it will control the dehumidification equipment to open. Control the opening sequence of dehumidification equipment: when the system judges that the current humidity value cannot be reduced to the target value within a certain period of time (adjustable from 0 to 99 seconds), it will open the dehumidification equipment sequentially; when the difference between the on-site humidity and the target humidity is large, the system will Control Jump to turn on one of the devices. Side window: open the side window ventilation system in sections to dehumidify, and follow this principle until the side window system is 100%. Dehumidifier Control: Turn on the dehumidifier for dehumidification. Alarm: If it is judged that the temperature falls below the target value, the computer will turn on the high humidity alarm, prompting the user to add dehumidification equipment. The system will constantly detect the on-site humidity, and when the on-site humidity tends to the target temperature, the system will shut down the dehumidification equipment.

(2) The humidity is lower than the standard value: For example, when the sensor with the ID number "123456789" detects that the humidity data on site is 40%RH, the data will be uploaded to the industrial computer through the wireless router and the wireless coordinator. In order to ensure that the humidity value is not an instantaneous value, the system will delay 0-90 seconds after receiving the data of the ID number for the first time, and then compare the values to accurately judge that the value is a trend value. The system will call out the standard value of 65%RH during this period and compare it with the field data. If it is judged that the temperature is 15%RH lower than the field temperature, it will control the humidification device to turn on. Control the opening sequence of humidification equipment: when the system judges that the current humidity value cannot rise to the target value within a certain period of time (0-99 seconds adjustable), it will turn on the humidification equipment sequentially; when the humidity on site is far from the target humidity, The system controls jumping to open one of the devices. Humidifier Control: Turn on the humidifier for humidification. Need to set the corresponding target value, the system will run automatically. Judgment time ensures that it is not judging the exceeding of the instantaneous humidity value, but judging the change of the overall trend of humidity; the control condition is activated only when the humidity value exceeds the standard within a certain period of time. The stable judgment time ensures that after the greenhouse equipment is started, it does not judge that the target value is reached instantaneously, but only after a period of stability. It avoids the rapid and repeated rise of the control condition; it also avoids frequent starting of the equipment motor, so as to better protect the motor. Alarm: If it is judged that the temperature falls below the target value, the computer will turn on the high humidity alarm, prompting the user to add dehumidification equipment. The system will constantly detect the on-site humidity, and when the on-site humidity tends to the target temperature, the system will shut down the humidification equipment.

2.3 Soil temperature control

(1) On-site data collection: Multiple wired sensors are placed in the greenhouse, and the sensors send data to the computer through cables from time to time.

(2) Control timing: the soil temperature is lower than the standard value: the sensor is a digital sensor with an ID number of 0-99 stored in it, and the digital signal is sent to the computer by the on-site transmitter. When the on-site temperature data is 15°C, in order to ensure that the humidity value is not an instantaneous value, the system will delay 0-90 seconds after receiving the data of the ID number for the first time, and then compare the values to accurately judge the humidity value. Value is a trend value. The system will call out the standard value of 25°C during this period of time, and compare it with the on-site data. If it is judged that the temperature is 10°C lower than the on-site temperature, it will control the heating device to turn on. Control the opening sequence of heating equipment: when the system judges that the current humidity value cannot be raised to the target value within a certain period of time (adjustable from 0 to 99 seconds), the heating equipment will be opened sequentially; when the difference between the site temperature and the target temperature is large, the system will Control Jump to turn on one of the devices. Inner sunshade insulation curtain: pull down the inner sunshade insulation curtain to prevent the indoor temperature from leaking out. External sunshade curtain: If the external light is strong, the external sunshade curtain can be opened to heat up through the light. Hot air stove, plumbing and air conditioning, heating: Turn on the heating device to increase the indoor temperature. Alarm: If it is judged that the temperature does not rise to the target value, the computer will turn on the low temperature alarm, prompting the user to increase the heating equipment. The system will constantly detect the on-site temperature, and when the on-site temperature tends to the target temperature, the system will shut down the heating equipment.

2.4 Illumination Control Sequence

The illuminance is lower than the standard value: Each plant has a different temperature growth curve, and the plants will have different suitable illuminance for growth in different time periods. For example, in each day, plants have various requirements for illuminance. This is because It is in different time periods and has different transformation functions. When the illuminance in the greenhouse is higher than the standard value, the system will automatically compare the difference between the standard value and the actual value in a certain period of time, and then control different equipment to adjust. For example: when the sensor with the ID number "123456789" detects that the illuminance data on site is 50lux, the data will be uploaded to the industrial computer through the wireless router and the wireless coordinator. In order to ensure that the illuminance value is not an instantaneous value, the system will delay 0~90 seconds after receiving the data of the ID number for the first time, and then compare the values to accurately judge that the value is a trend value. The system will call out the standard value of 300lux during this period and compare it with the field data. If it is judged that the temperature is 250lux lower than the field temperature, it will control the device to start regulation. Control the opening sequence of lighting equipment: when the system judges that the current illumination value cannot rise to the target value within a certain period of time (adjustable from 0 to 99 seconds), it will sequentially open the supplementary light equipment; when there is a large difference between the scene illumination and the target illumination, The system controls jumping to open one of the devices. Open the outer sunshade curtain: slowly open the outer sunshade to let the outdoor sunlight shine in. Open the inner sunshade: open the outer sunshade so that the outdoor sunlight can shine in. Fill light: Turn on the fill light for fill light. Alarm: If it is judged that the illuminance falls below the target value, the computer will turn on an alarm for high illuminance, prompting the user to increase the illuminance equipment. The system will constantly detect the on-site illuminance, and when the on-site illuminance tends to the target temperature, the system will turn off the lighting equipment.

2.5 wind speed for the protection of the external curtain

When the outdoor wind speed exceeds the protection value, the system automatically activates the wind speed protection function of the pull-out curtain. The condition level guarantees that the outer curtain will be automatically retracted in priority under abnormal conditions (for example: strong winds) to avoid catastrophic damage to the outer curtain. The judgment time ensures that it is not the judgment of the instantaneous wind exceeding the standard, but the change of the overall trend of the wind; the control condition is activated only when the wind exceeds the standard within a certain period of time. The stable judgment time ensures that after the greenhouse equipment is started, it does not judge that the target value is reached instantaneously, but only after a period of stability. It avoids the rapid and repeated rise of the control condition; it also avoids frequent starting of the equipment motor, so as to better protect the motor.

2.6 Protection of skylights by wind direction and wind speed

Strong wind, rain and snow protection: The system does not judge the instantaneous wind speed exceeding the standard, but judges the change of the overall wind trend, so as to close the ventilation window for protection when the wind is strong. The wind direction sensor can judge whether it is windward or leeward for different levels of protection.

2.7CO2 fertilization

Through the timing control setting, multiple groups of CO2 fertilization time rules can be selected.

2.8 Expert Database

The latest agricultural expert database is built in the system, and the corresponding optimal control scheme and parameters can be automatically invoked according to the production characteristics and requirements of different crops.

2.9 Data report and curve drawing

The recorded data can be exported to "EXECL" report, and at the same time, it can generate the change trend curve chart of the whole day, week and month.

3. Smart Greenhouse Terminal

3.1GSM wireless SMS alarm function

The system can realize "GSM wireless SMS alarm", and can quickly send "greenhouse alarm information" to relevant personnel's "mobile phone or PDA" in the form of SMS, requesting manual intervention. Different greenhouses and different administrator mobile numbers can be combined and associated through flexible settings. Therefore, an alarm in any greenhouse can be quickly sent to the mobile phones of one or more people related to the greenhouse.

3.2 Remote monitoring function

By connecting to the broadband Internet, the Internet remote login access function can be realized, which is convenient for remote monitoring.

Based on the ZigBee application technology of the Internet of Things, the system remotely obtains the air temperature and humidity, soil moisture and temperature, CO2 concentration, light intensity, outdoor weather and other parameters and video images in the greenhouse remotely in real time. Through simulation analysis, it can automatically control the greenhouse wet curtain fan. , sprinkler irrigation, internal and external sunshade, top window and side window, heating and supplementary light and other equipment to ensure that the environment in the greenhouse is suitable for crop growth. At the same time, the system can also push real-time monitoring and alarm information to managers through information terminals such as mobile phones, PDAs, and computers to realize intelligent remote management of greenhouses, improve economic benefits, and achieve green and energy-saving goals.

4. Design of Greenhouse Environmental Monitoring System Based on Bluetooth Technology

The components of Bluetooth technology mainly include wireless sensors, collection modules and monitoring cores. The components collect information to form the dissemination of information; in the traditional greenhouse control system, the requirement for the test point is to control the contact The way and position of the point, enhance the anti-interference ability, stabilize the operation performance, ensure that the humidity in the greenhouse reaches the standard, and meet the required light level. There are a large number of sensors and specific operating structures in the greenhouse. The existence of these facilities will greatly change the species in the greenhouse. Combining Bluetooth wireless technology to solve it is a good way to deal with it.

Bluetooth technology includes a lot of wireless sensors, collection modules and monitoring cores, which have a great effect on the layout of the greenhouse. Various high and low temperature sensing methods will be implemented for the temperature of the greenhouse. They will spread through Bluetooth as a medium, using wireless Relationship between sensing implementation and collection modules. The greenhouse acquisition module needs to exchange corresponding data information, and after receiving the order, make corresponding information transmission through the instruction.

4.1 System hardware facility planning

The implementation and utilization of bluetooth can be carried out in the following several planning methods: 1) commonly used dual-chip method: the protocol machine must be operated within the distance of the host mastering the protocol, and the protocol level is placed in the same complex resources as a PC. 2) Embedded dual-chip method: the protocol machine is mainly on the lower Bluetooth chip, and the master end is usually a processor with limited resources such as a mobile phone, and only the application protocol and the adaptation protocol are placed. 3) Embedded single-chip method: All protocols act together in an embedded organization, which is generally an unrelated, independent Bluetooth facility, the entry point of the Bluetooth network. It is necessary to study the actual operation site. The hardware requirement of the dental monitoring module is that the baseband, radio frequency, and protocol machine are built into a single-chip module. This method is mainly used for the collection channel of Bluetooth greenhouse environmental information.

4.2 Wireless Sensing Facilities

The sensor formed by the sensor and the Bluetooth collection module is mainly used to collect greenhouse data for the greenhouse. The main manifestations are as follows: 1) The sensor adopts ordinary temperature, humidity and other sensors. 2) The processor adopts AT89C2052 single-chip microcomputer. 3) The bluetooth module selects the universal blue fiber module 7708 composed of CSR bluetooth chips. The CSR chip integrates radio frequency, baseband, and a processor that can run bluetooth protocol machines and upper-layer applications. The chip interface is rich, providing standard UART interfaces and programming interfaces. And the volume is small, the module can be set up through the programming port, and the program can be downloaded. 4) Based on the CSR-BC212015 chip, the general-purpose Bluetooth module 7708 is realized, and the transmission power of 30dBm is used, and the communication distance can reach 100m. 5) Each device with a Bluetooth module can form a piconet, where data communication is performed in a master-slave manner. Since the MAC address of the Bluetooth module is 3 bits, only 8 devices (1 master device and 7 slave devices) can be activated at the same time. Of course, the master device can act as a slave device in another network at other times, so in actual communication, each network overlaps with each other.

5. Bluetooth software design

The system software mainly includes Bluetooth protocol implementation, sensor-side program, acquisition module-side program and monitoring center program. The bluetooth protocol implementation, the sensor end and acquisition module end programs are written in C51 programming language, and the monitoring center program is written in high-level language VisualBasic6.0.

5.1 Bluetooth protocol implementation

1) Bluetooth core protocol. All Bluetooth devices must comply with the Bluetooth regulations in order to meet the mutual communication between products of different manufacturers. The Bluetooth regulations are divided into core protocols and application aspects. The core stipulates that Bluetooth devices must meet the specified level, and the application stipulates that Bluetooth facilities in different application scenarios The corresponding implementation specification.

2) Bluetooth core protocol machine. These mainly include radio frequency, baseband, HCI, SDP, L2CAP, RFCOMM and other protocols. The baseband includes link control and link management, responsible for sending and receiving data, requesting names, link address queries, establishing connections, authentication, link mode negotiation and establishment, and determining frame types, etc. The Bluetooth radio frequency baseband (radio frequency unit, link control unit, link management unit) is usually implemented by a chip. Logical link control and adaptation layer protocols work together with the link management unit, and L2CAP provides connection-oriented and connectionless data services upwards.

L2CAP allows high-level protocols to send and receive data in 64K bytes.

3) Service Discovery Protocol (SDP). This technology is mainly used in discovering services provided by Bluetooth devices. The services and parameters provided by the Bluetooth device are registered in the SDP, and the Bluetooth devices using these services can query the information through the SDP. The serial port emulation protocol adopts the method of multiplexing to provide multiple transparent data channels, and the connection identification of each data link is jointly determined by the service channel number and the direction bit. The service channel number is the service identifier provided by RFCOMM. This service channel number should be registered in SDP. The client Bluetooth device can query this service channel number through SDP, and then initiate an RFCOMM connection to this service channel number.

5.2 Wireless sensor program design

The sensor-side processor first initializes the Bluetooth module, collects various crop and environmental information, and then encapsulates the information into data in the form of: information type + information value + acquisition time.

5.3 Program Design of Acquisition Module

The program of the acquisition module is mainly used for system initialization (including system and Bluetooth module initialization and communication port settings), data reception and processing, etc. Firstly, the information of each sensor is received, and then the encapsulated data is decoded, and various crop growth and environmental information are separated for storage. At the same time, it waits for the commands from the monitoring center to perform system settings and data query and transmission. Monitoring center program design The monitoring center program is mainly for the setting of the acquisition module, data reception, command sending and historical data query, etc.

5.4 Self-Organizing Software Implementation

1) Chip processing technology. In the CSR chip, the written application program and the protocol machine run together in the CSR embedded environment. CSR provides the Bluetooth core protocol machine in the form of firmware (fire, ware), including HCI, L2CAP, SDP, RFCOMM, and also provides Application programming interface, which defines and implements all interfaces and services that users need to access during the development process, including: scheduler, Bluetooth protocol, memory access, HCI transport layer settings, messages and timers, and serial port flow management.

2) Information processing technology. Different tasks in the CSR program can send messages asynchronously. Each task can have a message queue when it is created. The task scheduler can automatically run the task to obtain the message. CSR provides a connection management to simplify the use of the RFCOMM protocol. Library, which encapsulates most of the commonly used link management interfaces. But the CM library provided by CSR only provides point-to-point connection. In order to realize point-to-multipoint connection, the CM library is modified to support point-to-multipoint. Based on the HCI, L2CAP, SDP, RFCOMM protocol and CM library provided by CSR, the program of Bluetooth wireless sensor application is written.

Summarize

To sum up, in the comprehensive introduction to Bluetooth information technology, it is concluded that the implementation of Bluetooth technology information collection in greenhouse monitoring is a deepening of the overall system, and it has realized an unprecedented design concept. The application of this technology, in Without raising the cost, it overcomes the difficulty of traditional data information collection and the disadvantages of system maintenance and installation, and applies the new technology of wireless channel to greenhouse monitoring.

The above are the design details of the smart greenhouse system scheme introduced by Shenzhen Zuchuang Microelectronics Co., Ltd. for you. We have rich experience in customized development of 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, Bluetooth IC and module, wifi module. Our development capabilities cover PCB design, single-chip microcomputer development, Bluetooth technology development, software customization development, APP customization development, WeChat official account development and other hardware and software design. 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 development of electronic education products.