In daily life, temperature and humidity are two important physical parameters. It is not only closely related to people's health, but also closely related to scientific research, garden technology, warehouse management, and computer room management. With the development of electronic technology, people are increasingly demanding environmental temperature and humidity monitoring. The traditional temperature and humidity detection technology uses wired transmission devices, which not only has troubles in wiring, but also consumes a lot of manpower and material resources, and has great limitations in practical applications.
This paper designs a wireless temperature and humidity detection system scheme. The main controller adopts STM32, and the wireless transceiver module chip selects nRF24L01P. The sensor uses digital temperature and humidity sensor AM2303 with low power consumption, fast response and strong stability.
1, system design block diagram
Figure 1 System transmission block structure block diagram
The system is a "many-to-one" system [2], which consists of several wireless transmitting modules and one wireless receiving module. The block diagram of the system sender is shown in Figure 1. At the transmitting end, the STM32 controls the temperature and humidity data acquisition of the AM2303 and wirelessly transmits data using the nRF24L01P. The block diagram of the system receiving end is shown in Figure 2. At the receiving end, STM32 controls nRF24L01P to realize the wireless receiving function of multiple sets of data, and transmits the received data to the upper computer through the serial port, and the upper computer processes, analyzes and displays the data in real time.
Figure 2 system receiving end structure block diagram
2, system hardware designThe system hardware design consists of STM32 MCU main control circuit, wireless transceiver circuit, temperature and humidity data acquisition circuit, alarm circuit, power supply circuit, etc. It mainly completes the real-time collection, transmission and display of temperature and humidity data.
2.1, STM32 microcontroller control circuitThe system adopts STM32F103RBT6 produced by ST Company as the control core. STM32F103RBT6 is a 32-bit processor product of ST's latest Cortex-M3 architecture core based on ARM. Its processing speed can reach 72MHz, built-in 128KB Flash, 20KB SRAM, 12-bit A. /D, four 16-bit timers, three USART communication ports and two SPI interfaces, and other rich on-chip resources, fully meet the requirements of the detection system for data acquisition, processing, transmission and other applications. As the main controller of the system, STM32F103RBT6 controls the nRF24L01P chip to realize the wireless transceiver function of data through the SPI1 interface, and performs corresponding conversion processing on the received data to communicate with the host computer through the RS-232 serial bus.
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