Brief Introduction to the Principle of Temperature Collection Alarm System

The temperature acquisition system mainly acquires temperature data through the temperature sensor MAX6613. MSP430F149, as the CPU, reads data from the temperature sensor, judges the data and then performs corresponding processing, such as display or alarm. The temperature sensor can obtain the relationship between temperature and output voltage through a certain relationship conversion. For MAX6613, the relationship between its output voltage and temperature is shown in the figure.

Figure MAX6613 sensor output voltage and temperature relationship

In order to facilitate calculation, the temperature and voltage conversion equation is:

VOUT=-0.0000022xT2-0.01105xT+1.8455V (4-1)

However, in most cases, the following linear relationship can also be used to complete the conversion operation.

VOUT=-0.0123xT+1.8455V (4-2)

The input voltage of the sensor, and then the temperature parameters can be obtained through the above formula (4-2). After analyzing the obtained temperature parameters, corresponding processing is performed, such as display or alarm. Since the MSP430F149 chip integrates A/D conversion channels, the A/D input channel of the microcontroller can be directly connected to the analog voltage output channel of the sensor. In addition, the system completes the setting of the upper and lower limits of the alarm temperature through keyboard input, and displays the obtained data through the display circuit. When the temperature exceeds the upper and lower limits, the system alarms, and the alarm is achieved by driving a buzzer.