关键词: 嵌入式温度模块, Cortex-M3, 热电阻测温, 热电偶测温

Abstract: An embedded temperature module of intelligent controller is designed based on Cortex-M3 core STM32F100C8T6 microcontroller. The module has 4 thermal resistance temperature measuring circuits, which can realize the temperature detection of Pt100, Cu50 and other thermal resistances. There are 2 thermocouple temperature measuring circuits, and the new thermocouple chip MAX31855 is used to realize the temperature detection of 8 kinds of thermocouples such as K type and J type. There are 4 analog input circuits and 2 analog output circuits.? The temperature module uses SPI to communicate with the main control CPU of the intelligent controller. SPI communication uses chip SI8441 for photoelectric isolation. ADC circuit uses 12-bit resolution conversion circuit of embedded processor; DAC circuit outputs 4-20 mA current with 0.05% resolution through XTR111 chip based on PWM wave modulation principle. The power supply part adopts a DC-DC isolated power supply module to form a fully isolated signal system and a power supply system. The test results show that the acquisition error of thermal resistance and thermocouple signal is less than 0.1 ℃.

Key words: embeddedtemperaturemodule, Cortex-M3, temperaturemeasurementbythermalresistance, thermocoupletemperaturemeasurement