The STM32 embedded system is widely used in various control applications. Based on the Cortex-M3 core, it offers high performance, low cost, and low power consumption, making it ideal for real-time control systems. Despite the availability of numerous temperature and humidity monitoring systems on the market, few are designed with low power consumption and self-contained data recording capabilities, often at a high price. This paper presents a low-power temperature and humidity acquisition system based on the STM32F103RET6 microcontroller. The system can operate for approximately 30 days, utilizing a stop mode to minimize power usage. It employs the SHT10 sensor for temperature and humidity measurement, with a data acquisition cycle of 5 minutes. Powered by an 18650 lithium battery, the system includes SD card storage, USB full-speed communication, and serial communication interfaces.
**1. Temperature and Humidity Collector Design**
**1.1 Hardware Design**
The collector's structure is illustrated in Figure 1. It consists of a power supply module, a USB full-speed communication module, the STM32 microcontroller, an SD card storage module, a temperature and humidity sensor, a serial communication module, and a JTAG debugging interface. To ensure compactness, the system uses a 18650 rechargeable lithium battery. A fully charged 2400mAh battery can support operation for about two months. The STM32 is powered through a HT7333 step-down module provided by He Qin. The Real-Time Clock (RTC) controls wake-up intervals every 5 minutes for data collection. The SHT10 sensor is used to acquire temperature and humidity data using a custom communication protocol. Collected data is stored in hexadecimal format on the SD card. Users can retrieve the data via serial communication, USB full-speed communication, or directly from the SD card.
**1.2 SHT10 Temperature and Humidity Sensor Communication Timing**
The communication timing for the SHT10 sensor is shown in Figure 2.
Figure 2 SHT10 timing diagram
After power-up, the sensor requires a rising edge of at least 1V/ms before entering a 11ms sleep state. During this time, no commands are sent. To initiate data transfer, a "start condition" must be generated. The start timing involves pulling the DATA line low while the SCK clock is high, followed by pulling it back high after the SCK goes low. Subsequent commands include three address bits and five command bits. After receiving the command, the sensor pulls the DATA line low (ACK bit) on the eighth falling edge of SCK. On the ninth falling edge, the DATA line is released and returns to a high level. This protocol ensures accurate and reliable data exchange between the STM32 and the SHT10 sensor.DELL chromebook 11 3110, dell chromebook 3110, ddell chromebook 3110 2-in-1
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