In recent years, there have been many greenhouse greenhouse monitoring devices using GPRS technology in the domestic and foreign markets. The technology and equipment have large transmission information, can be remotely controlled and have high reliability, but their equipment cost and communication fee are higher. High, so it is difficult to get widely promoted. Therefore, the author developed a greenhouse greenhouse monitoring system based on Zigbee technology, which has the advantages of low power consumption, low cost, high reliability, low complexity, simple installation and maintenance, and strong expansion, which is the promotion of greenhouse greenhouse monitoring system. Provide a rare platform.
1 Zigbee wireless communication technology system structure
Zigbee is an emerging wireless network communication protocol conforming to the IEEE 802.15.4 standard. Its sponsoring organization Zigbee Alliance released the earliest version 1.0 specification at the end of 2004, and subsequently launched two upgraded versions of Zigbee2006 and Zigbee PRO. Most of Zigbee's products are still in the research stage, but given its many advantages, it is believed that products based on Zigbee technology will soon be widely used.
1.1 Main features of Zigbee technology
1) Low power consumption. In the low-power standby mode, two No. 5 dry batteries can support one node for 6 to 24 months, or even longer.
2) Low cost. By greatly simplifying the protocol (less than 1/10 of Bluetooth), the requirements for communication controllers are reduced.
3) Low rate. It provides 250 kbps raw data throughput at an operating frequency of 2.4 GHz, meeting the needs of low-speed data transmission applications.
4) Close range. The transmission range between adjacent nodes is generally between 10 and 100 m. After increasing the RF transmission power, it can also be increased to 1 to 3 km.
5) Short delay. Zigbee's response speed is relatively fast, generally only 15 ms from sleep to working state, node connection into the network only 30 ms, further saving energy.
6) High capacity. Zigbee can be used in star, patch and mesh networks, and a master node can manage up to 254 child nodes.
7) High security. Zigbee offers a three-level security model.
8) Free license band. Direct sequence spread spectrum is used in the Industrial Scientific Medical (ISM) band.
1.2 System structure of Zigbee protocol
The system structure of the Zigbee protocol is shown in Figure 1.
The main controller used in this design is the CC2430 wireless MCU produced by American TI Company. The MCU carries the system-on-chip (SoC) of Zigbee technology, and is an enhanced 51 MCU. It is a highly integrated system-level RF transceiver. Its main features are as follows:
1) The relevant RF circuit has been integrated inside the chip, so the peripheral interface circuit is relatively simple.
2) The chip is an enhanced 8051 microprocessor with built-in watchdog, AD conversion and other modules, so it is powerful.
3) The chip is inexpensive and has a simple peripheral circuit, so it has a low development cost.
2 system hardware components
In the system, according to the functional hardware composition, it can be divided into two parts: the sensor terminal device and the central control device. The terminal device realizes the data acquisition of the monitoring point and the drip irrigation switch, the opacity angle adjustment stepping motor, the fluorescent lamp and the ventilation device control; The central control device performs processing comparison and control output on the data collected by each terminal.
2.1 Sensor terminal
The sensor terminal device is composed of an RF transceiver module, a sensor module and an actuator driver module. The actuator drive module is mainly composed of a relay circuit, and the sensor module is composed of a digital temperature sensor DS18B20, a digital humidity sensor SHT21, a miniature digital carbon dioxide sensor S-100 and a TSL230B light intensity/frequency sensor chip, and the RF transceiver module uses It is the CC2430 wireless transceiver module provided by TI company. The specific circuit principle is shown in Figure 2.
Ic Data Acquisition,Data Acquisition Analog Front End,Data Acquisition Analog To Digital Converters,Data Acquisition Digital To Analog
Shenzhen Kaixuanye Technology Co., Ltd. , https://www.icoilne.com