Development and design of greenhouse control system

With the improvement of people's living standards, the demand for flower appreciation and flower use is increasing. People try to break through the temperature limit, so as to realize the cultivation of a wide variety of flowers in various regions and climates. The flower greenhouse controls the development. There are more and more, but the manpower and material resources required are huge, and the benefits are not very obvious. In view of this, we have designed a greenhouse control system based on single-chip technology to make the greenhouse more effective. Even in small-scale and incompletely equipped flower houses, it can play most of the roles, and it can also provide good news for some flower farmers with poor conditions.

1. Greenhouse and Greenhouse System Design Scheme

This project is a greenhouse control system based on single-chip technology. Based on the various sensors and devices controlled by the main control chip, this design meets the basic purpose of multi-directional data collection and intelligent automatic regulation. At the same time, GSM remote communication is added to remotely set any environmental parameters on an automatic basis. To meet the specific needs of flower farmers for the environment of different flowers in different growth periods. On such a basis, it can realize multi-functional, all-weather regulation of the environmental factors of the greenhouse, and also ensure the characteristics of real-time sampling and detection. Due to the simple device and clear features, the system-wide device can be reasonably scaled according to the shape and size of the greenhouse, ensuring that flower farmers of all sizes can use convenient and intelligent devices on a relatively economical basis. The block diagram of the system is shown in Figure 1.

The main control platform is established by using STC15 series single-chip microcomputer, combined with various sensors and GSM (SIM300) communication module for greenhouse parameter collection. The sensor collects all kinds of environmental information (temperature, humidity, carbon dioxide concentration, light intensity, oxygen concentration, etc.) in the greenhouse in real time and transmits them to the single-chip microcomputer. Control the degree of regulation and control the effector for moderate regulation so that the target parameter returns to an appropriate range. This design supports the user to actively command through the mobile phone to collect the current data of the greenhouse under the premise that the flower grower is far away from the greenhouse, and can remotely reset the data range to meet the special needs of various flowers in different growth periods.

2. Communication description between MCU and GSM module

The communication between the single-chip microcomputer and the GSM module adopts the 232 communication interface, and the key of the software is to do a good job in the operation of the single-chip microcomputer to the AT command of the mobile phone. The GSM module adopts SIM300, and SIM300 has a standard serial communication interface and interfaces with the microcontroller after level conversion by MAX232. Set the working mode of the SIM300 module to PDU mode. Using the text mode to send and receive text messages has a simple code and is easy to implement, but the biggest disadvantage is that it cannot send and receive Chinese text messages; while the PDU mode not only supports Chinese text messages, but also can send English text messages. PDU is equivalent to a data structure, which includes source and destination addresses, valid time, data format, protocol type and text.

3. Advantages of Greenhouse Greenhouse Control System Solution

Compared with manual control, the biggest advantage of greenhouse intelligent control is that it can control the environment inside the greenhouse relatively constant. For plants with high environmental requirements, it can avoid production losses due to human factors. Compared with production, it will After the intelligent control system is applied to flower production, the cultivation of flowers has been greatly improved compared with the artificially controlled greenhouse. For different flower varieties, the appearance and survival rate are guaranteed. For the precious varieties with higher grades, Production efficiency can be greatly improved. The application of automatic control technology in the greenhouse can achieve the purpose of improving the quality of flowers, adjusting the growth cycle, and improving economic benefits, especially the efficient and accurate management of greenhouses. For large-scale greenhouse facilities, if the environmental conditions in the temperature greenhouse are controlled manually, a lot of manpower and time are required, and there are unavoidable manual errors. If the GSM automatic control technology is applied, the user only needs to send a short message to the GSM through the mobile phone, and the single-chip microcomputer receives and recognizes the command information and performs corresponding operations. It replaces manual operation in the shortest time and completes the intelligent control of the greenhouse. Greatly avoid the disadvantages of over-reliance on the network that make the remote and small greenhouses in this sub-region unable to install intelligent control devices.

Temperature plays an extremely important role in everyday life. Such as cold storage temperature monitoring, pharmaceutical factory monitoring system, telecommunications room monitoring, building automation, warehouse temperature monitoring, environmental monitoring, process temperature monitoring, central air conditioning monitoring, agricultural temperature greenhouses and many other fields have good application prospects. The key technology here involves information collection (ie sensor technology), information transmission (communication technology) and information processing (computer technology). Sensors belong to the cutting-edge products of information technology, especially temperature sensors are widely used in industrial and agricultural production, scientific research and life, and the number ranks first among all kinds of sensors. Temperature sensors are developing rapidly from analog to digital, from integration to intelligence and networking. DS18B20 is a high-precision digital temperature sensor that can be networked. Due to its advantages of single bus, it is very suitable for building a high-precision, multi-point networked temperature measurement system, and realizes real-time collection, display, and ultra- Limit alarm, data recording, historical query, curve drawing and other functions. Therefore, it is of practical significance to study how to set up a multi-point temperature monitoring system based on an embedded operating system using a digital temperature sensor (DS18B20).

4. Design principle of ARM-based greenhouse temperature monitoring system

The system is a real-time operating system? C/OS-П, high-speed ARM microcontroller, digital temperature sensor, LCD display, Flash storage and other 5 units. A new distributed high-speed multi-point greenhouse temperature monitoring system that realizes data transmission with the host computer through RS232/RS48 serial port communication.

The core component of the system is that the ARM microprocessor sends control signals to the temperature sensor, the temperature sensor collects temperature data and transmits it to the ARM processor, and the processor displays the collected data in real time through the LCD and stores the temperature data into the Flash at regular intervals Through the UART serial port, the saved temperature data is transmitted to the host computer by cable (RS232/485) to realize the establishment of the database, and store these data for a long time for future viewing. The historical database is displayed in the form of numerical values and dynamic curves to realize historical data Print it for later analysis and research, or remind users to perform corresponding operations.

5. Construction of the hardware platform and device selection of the greenhouse system

(1) Control platform: If ARM9 is used as the control platform of the temperature measurement and control system, it will not only have fast speed, high performance, low power consumption, high chip integration, but also rich peripheral interfaces, and can also transplant embedded real-time operating system, which simplifies LCD Design and development of display, storage, network communication, etc. The system adopts the ARM 9 experimental teaching development board Embest EDUKIT-П/Ш of Embest Company.

(2) Selection of system bus: Strict communication protocol can guarantee the correctness and integrity of data transmission. Set up a multi-point temperature monitoring to host computer/slave computer communication system, considering the cost, transmission distance, transmission rate, transmission direction, and the number of transceivers allowed to be connected on the bus, for example, RS232 only allows one transceiver to be connected ; The RS-422 bus protocol adopts a one-way transmission mode; the RS-485 bus protocol adds multiple points and has two-way communication capabilities, which allows multiple transmitters to be connected to the same bus, and at the same time increases the drive capability and conflicts of the transmitters protective properties. Therefore, choose the RS-485 protocol with relatively low cost and relatively long communication distance to communicate between the lower computer and the upper computer.

(3) Selection of data acquisition unit: The "1-wire-bus" feature of the temperature sensor (DS18B20) can conveniently make each module have an independent address, and its advantages are (1) Only use one ARM The port line can communicate with many DS18B20, occupy less ports of the microprocessor, can save a lot of leads and logic circuits, can easily realize the expansion of intelligent units, and form a multi-point multi-sensor signal acquisition system; (2) On-site temperature It is directly transmitted in the digital mode of "one-line bus", which greatly improves the anti-interference performance of the system, and is suitable for on-site temperature measurement in harsh environments. (3) The corresponding bus modules equipped with the new field bus have extremely strong networking characteristics. , Humidity measurement and control network has been developed rapidly.

The temperature measurement network constructed by embedded high-speed microprocessor ARM and single-bus digital temperature sensor DS18B20 has flexible and convenient design, strong anti-interference ability, high resolution, high-speed data processing, and is suitable for on-site temperature measurement in harsh environments . Therefore, the system designed in this text adopts DS18B20 digital temperature sensor.

(4) Data acquisition and serial communication functions: Since the embedded system integrates UART serial components to exchange data, serial communication is the most basic means of communication. In the system, the DS18B20 in the system is responsible for temperature collection, the ARM processor is responsible for processing and control, and the upper computer performs on-site visual inspection to display the data collected by the lower computer and set various parameters for the lower computer. The serial port UART0 of the Embest EDUKIT-П/Ш development board communicates with the PC to form a bus-type temperature measurement network system.

(5) LED display and control: the common cathode 8-segment digital tube is used to display the temperature, and the display is controlled by ZLG7290, in which the DIG1~DIG8 pins output the bit drive signal required by the LED display, while the SEGA~SEGG and DP pins output LEDs show the desired segment drive signal.

(6) Watchdog circuit: The watchdog circuit is an effective measure to ensure the long-term, reliable and stable operation of the system. After the microcontroller is disturbed and enters an error state, the system is reset within a certain time interval. The watchdog The timer will send a reset signal every 128 system clock cycles, and it can also be used as a general-purpose 16-bit interrupt timer to request interrupt service.

Summarize

The greenhouse control system based on single-chip microcomputer technology can not only solve the temperature and light control problems of facility greenhouses, but also provide necessary technical support for the standardization and scale modernization of flower cultivation. At the same time, GSM implements remote manual control and real-time monitoring of the greenhouse. Users control various parameters of the greenhouse by sending information instructions to ensure that the parameters are within the preset range, reduce the pressure on laborers, save time, reduce expenses, and increase Income has far-reaching practical significance.

The embedded remote monitoring system that combines embedded system with fieldbus technology and Internet technology can expand the monitoring range to a larger space, further promote the development of control technology to network, decentralization and openness, and will become an industrial One of the important development directions of the control network. The ARM-based multi-point temperature monitoring system is not only simple in circuit, but also convenient and practical. It is also possible to add more monitoring signals on the basis of the system, such as humidity, pressure, etc.; it is also possible to realize remote monitoring through on-site display, wired transmission, wireless transmission, etc. Diversification is possible.

The above are the details of the green house and greenhouse system solution introduced by Shenzhen Zuchuang Microelectronics Co., Ltd. for you. If you have technical development needs for IoT products, you can trust us. We have rich experience in customized development of electronic products, and can evaluate the development cycle and IC price as soon as possible, and can also calculate PCBA quotations. 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.