Circuit Lake

Electronic Project and Circuit Collection

AVR Thermocouple Temperature Meter

07/13/2012 Category: AVR, Data Acquisition, Measurement, Microcontroller, Project, Sensor

The benefit using thermocouple sensor for measure temperature is it has wide range measurement (-200 °C to +1350 °C / -328 °F to +2462 °F range for Type K), inexpensive, interchangeable, and is supplied with standard connectors. To get temperature value from output of a thermocouple, you need high precision amplifier and proper compensation circuit due to its small and relativistic output voltage.

Thermometer using thermocouple

This handy Thermocouple Temperature Meter is build based on ATmega164 microcontroller. The project uses MAX31855 thermocouple interface IC from Maxim. It integrates analog circuit and even the A-D converter, and outputs the temperature value in digital data. A digital LCD panel meter, TWV1302W, is used to display the temperature value. The project has serial data output port for temperature logging to PC. LR1 cell with step-up DC-DC converter is used as power source for this project. It can produce 4mA at 1.5V.

Firmware for ATmega164 is simple. It reads the temperature data from MAX31855 in interval of 0.5 second and displays it to the LCD panel and transmitted as serial data.