Medium low temperature measurement system based on K-type thermocouple

K-type thermocouple, as a major temperature measuring element, has the characteristics of simple structure, convenient use, wide temperature measurement range, and high temperature measurement accuracy. However, there are several issues with the application of K-type thermocouples.
1) Nonlinear. The output thermoelectric potential of thermocouples is non-linear with temperature, therefore linearization is necessary for application.
2) Cold compensation. The thermoelectric potential output by the thermocouple is the difference between the potential at the cold end when it is maintained at 0 degree and the measuring end. However, in practical applications, the temperature at the cold end varies with the ambient temperature, so cold end compensation is required.
3) Signal output. The output signal of K-type thermocouple is an analog signal. In order to facilitate connection with subsequent microcontroller circuits, it is necessary to convert the analog signal into a digital signal.
MAX6675 [0] is a thermocouple amplifier and digital converter that integrates thermocouple amplifier, cold junction compensation, A/D converter, and SPI serial port.