1. Description of requirements
1.1 Summary of Design Requirements
With the development of the times and the improvement of people's living standards, the requirements for the quality of refrigerated and frozen foods are also increasing. Therefore, it is of great social and economic significance to design a complete cold storage temperature detection and control system.
Currently, a cold storage environment detection system for kiwi fruit storage is designed based on STM32. This system can accurately display the real-time temperature of the monitoring points in the cold storage. There is an LCD display outside the cold storage, which can display the actual temperature of the cold storage in real time; the system can be set The temperature threshold of refrigeration can be adjusted by pressing the button. If the temperature is higher than the threshold, the refrigeration will be turned on automatically, and if the temperature is lower than the threshold, the refrigeration will be stopped. The system is also equipped with a flame detection sensor. The buzzer will give an alarm reminder; after the warehouse door is closed, if the lighting in the warehouse is not turned off, it will be reminded by a buzzer. This light detection function is detected by a photosensitive sensor, which detects the light intensity of the warehouse to determine whether to turn off the light.
The hardware equipment required for the current design:
(1) STM32F103 system board: As the main control chip of the current system, it combines each module to complete the final functional design.
(2) Buzzer: When the light is not turned off, or when a fire is detected, it will sound an alarm.
(3) BH1750 photosensitive sensor: detect the environmental intensity in the cold storage, and judge whether to turn off the light.
(4) Relay: It is used to control the refrigeration module to realize the refrigeration of the cold storage.
(5) PT100 platinum resistance temperature sensor: used to detect the temperature of the cold storage, pt100 is a platinum thermal resistance, and its resistance value will change with the change of temperature. The 100 after PT means that its resistance is 100 ohms at 0°C, and its resistance is about 138.5 ohms at 100°C. Acquisition temperature range is -200°C ~ +200°C