This project demonstrates high-resolution temperature measurement using the MAX31856 thermocouple-to-digital converter with an STM32F103C6 microcontroller.
The MAX31856, featuring a 19-bit ADC, supports multiple thermocouple types (K, J, N, T, S, R, E, B), performs cold-junction compensation, and includes fault detection for out-of-range conditions, shorts, and open thermocouples.
Integration with the STM32 via SPI communication ensures accurate and efficient temperature acquisition. The DRDY (Data Ready) pin signals when new data is available, enhancing system responsiveness. This makes the solution robust for industrial and scientific applications requiring precise thermal monitoring.
STM32CubeMX Setup- MCU Selection: STM32F103C6 (8 MHz clock)
- SPI1 Configuration:
- Mode: Full-Duplex Master
- Prescaler: 32 (250 kHz clock)
- CPOL: Low, CPHA: 1 Edge
- GPIO Configuration:
- PA4 → Output (Chip Select)
- PA3 → Input (DRDY Interrupt)
- UART1 Configuration:
- Mode: Asynchronous
- Baud Rate: 9600
- Word Length: 8 bits
- Generate initialization code in STM32CubeIDE.
Key Functions
- MAX31856 Initialization
- void MAX31856_Init(void) → Configures registers, sets thermocouple type, enables conversion
- Multi-Thermocouple Support
- void Set_Thermocouple_Type(uint8_t type) → Selects thermocouple type (K, J, N, T, etc.)
- Temperature Reading with Fault Check
- float Read_MAX31856_Temperature(void) → Reads temperature, checks for faults, returns °C
- Main Loop
float temp = Read_MAX31856_Temperature();
printf("Temperature: %.2f°C\r\n", temp);Required Components
- STM32F103C6 microcontroller
- MAX31856 thermocouple amplifier
- K-Type Thermocouple
- Virtual Terminal (UART display)
Steps
- Connect SPI lines:
- PA5 → SCLK, PA6 → MISO, PA7 → MOSI, PA4 → CS
- Connect PA3 → DRDY pin of MAX31856.
- Connect UART1 (PA9 → TX) to Virtual Terminal.
- Load the .hex file from CubeIDE into Proteus.
- Configure thermocouple type in MAX31856 properties.
- Run simulation → Adjust thermocouple temperature in component properties.
- Monitor real-time output on the Virtual Terminal.
That's all!
If you have any questions or suggestions don't hesitate to leave a comment below
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