chp_10.1007_978-981-10-0421-6_8.docx
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1、Agricultural Data Acquisition and Communication Embedded System Based on MSP430 Hua-Jie Cao1(&), Hao-Dong Liu2, and Ming Liu3 1 School of Information Technology, Southwest Jioatong University, Chengdu 611756, Sichuan, China 2 School of Electrical Engineering, Southwest Jioatong University, Chengdu
2、611756, Sichuan, China 3 School of Information Science and Mathematics, Changzhou University, Changzhou 213164, Jiangsu, China Abstract. Under the background of big data and cloud computing, in order to design a kind of agricultural data collection and communication system, MSP430 is taken as core
3、 controller and processor. DS18B20 as temperature acquisition, DHT11 sensor as humidity data acquisition, BH1750FV1 as light sensor. The collected data will be transmitted through the wireless communi- cation module, and communication with the host computer. The design of the system is divided into
4、hardware design and software design. This system can extend to join the ZigBee or BeiDou communication module, which can be applied to the large-scale intelligent agricultural control. Keywords: Agricultural data acquisition MSP430 Temperature and humidity sensor Wireless communication 1 Introductio
5、n At present, Chinas agricultural production efciency is not high mechanization and information technology is also not high. Due to various reasons, farmland is not easy to management directly 1. With the development of the Internet of things (IoT), the IoT technology will quickly penetrate into eve
6、ry link of agriculture. Temperature, humidity, light intensity and other data are important environmental parameters in agricultural production, especially in greenhouse cultivation, aquaculture and other precision agriculture. They are essential for agricultural production, these parameter will dir
7、ectly affect the quality of agricultural production and agricultural production, especially in the environment changes, if not check and control timely, agricultural production will cause serious damage 2. In many agricultural and even industrial applications, the measurement of process, production
8、and environmental parameters is still a real time monitoring. The purpose of this design is to study the distributed node control and Springer Science+Business Media Singapore 2015 X. Zhang et al. (Eds.): ESTC 2015, CCIS 572, pp. 7786, 2015. DOI: 10.1007/978-981-10-0421-6_8 78 H.-J. Cao et al. commu
9、nication program, to further promote, it can be suitable for large-scale infor- mation agriculture. 2 Overall System Architecture The wireless data acquisition and communication system including three parts, the rst part is the universal application of DS18B20 as the core of the temperature measure-
10、 ment module, the digital sensor DHT11 as the core of the humidity measurement. BH1750FV1 is used for light intensity. In this system, NRF24L01 is selected for the wireless transceiver module. The microcontroller is MSP430, it is mainly responsible for real-time data display, and it can communicate
11、with PC through the USB interface, which can achieve real-time monitoring of temperature, light intensity, humidity and record the results of the measurement. The architecture diagram of this system is shown in Fig. 1. Fig. 1. Architecture diagram of this system 3 Hardware Design of This System The
12、hardware part is composed of MSP430F149 microcontroller, temperature sensor DS18B20 module, humidity sensor DHT11 module, light intensity sensor BH1750FV1 module, NRF24L01 wireless transceiver module and 1602 LCD module. The sender is to complete the measurement of three parameters which is temperat
13、ure, humidity, light intensity, and send them to the LCD for real-time display in the premise of high accuracy. The measurement data will be also send to the receiver. On the receiver, the received data will also display in the PC terminal for real-time monitoring and saving. Agricultural Data Acqui
14、sition and Communication Embedded System 79 The following will highlights the DS18B20 sensor, DHT11 humidity sensor and BH1750FV1 light intensity sensor and other modules. 3.1 Design of Temperature Sensor Circuit Temperature controller has been widely used in metallurgy, textile, chemical, medical a
15、nd many other elds. In this design, the temperature sensor uses DS18B20, which uses the three wire interface, which is a signal bus type device. It has the advantages of miniaturization, low power consumption, strong anti-interference ability, simple inter- face, high performance and so on, which ca
16、n be directly converted to digital signal Fig. 2. Temperature sensor circuit processing. Composed with the traditional method of thermocouple temperature mea- surement, DS18B20 can greatly improve the accuracy of temperature measurement, and its three-wire connection is very convenient. DS18B20 pins
17、 are power pin GND, data signal pin DQ and power supply pin VDD. Its application circuit is shown in Fig. 2. 3.2 Design of Humidity Sensor Circuit DHT11 digital humidity sensor is a kind of serial bidirectional interface, which has the advantages of fast response, strong anti-interference ability an
18、d high cost performance ratio. As shown in Fig. 3, a typical application circuit for the DHT11, if the signal between master and slave length of less than 20 m, a pull-up resistor will be required between data side and VCC. The typical value of the resistor is 4.7 K. When the signal line is more tha
19、n 20 m, the resistor should be adjusted resistance. 3.3 Design of Light Intensity Sensor Circuit BH1750FV1 is a digital intensity sensor integrated module, using two wire serial bus interface. In comparison with the analog device, the BH1750FV1 is more stable, less power consumption, simple hardware
20、 circuit interface. In the software design, it uses IIC protocol, which has a high transission efciency. The sensor adapt the double-wire 80 H.-J. Cao et al. Fig. 3. Typical circuit for DHT11 connection with the microcomputer. The communication between the two is followed by the IIC protocol, and th
21、e microcomputer provides the data transmission ports and simulation sequence. The SCL port and SDA port are respectively connected with the output port clock interface and data interface. As is shown in Fig. 4. Fig. 4. Circuit of BH1750FV1 4 Software Design of This System The software of the whole s
22、ystem is designed by each subroutine, which is composed of temperature measurement module, humidity measurement, light intensity data acquisition program and wireless communication program. After the initialization of Agricultural Data Acquisition and Communication Embedded System 81 the microcomput
23、er, the data of each sub module is collected, the data is transmitted through the wireless module and the other receiver also transmit the received data to the PC terminal. The program design of each sub module are introduced respectively. 4.1 Temperature Acquisition Program DS18B20 requires for a p
24、eriod of time waiting for the internal register to complete the rst numerical prole. The rst step is to set up the temperature register when it is in normal work, set the corresponding to 55. The temperature data is divided into high 8 bit and low 8 bit, working with 12 bit accuracy, the temperature
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