⚠️ THIS FEATURE IS AVAILABLE ON CC2652 or CC1352 CHIPS ONLY

MAX31855

MAX31855 (buy on AliExpress) performs cold-junction compensation and digitizes the signal from a K-, J-, N-, T-, S-, R-, or E-type thermocouple. The data is output in a signed 14-bit, SPI-compatible. Because data is read-only, (the sensor does not have any configuration options), the MOSI pin is not required.

This feature should also work with the obsolete MAX6675.

1. Define the SPI CS pin and select the “MAX31855,MAX31865” from the list.
2. Select the MISO pin from the list in the “Pin (MISO)” field.
3. Select any unused pin in the “Pin (MOSI)” field because it is not relevant and the chip implements one-directional data transfer.
4. Select MAX31855 in the “Type” list.
5. Other options are not applicable for MAX31855.
6. Immediately after the CS pin (Output 1), define the “SPI CLK” pin (Output 2 in the example above).

Note: You can share “MISO” and “CLK” pins between several sensors.

MAX31865

The MAX31865 (buy on AliExpress) is a precision RTD-to-digital converter designed to interface with platinum resistance temperature detectors (RTDs), offering high accuracy and compatibility with 2-wire, 3-wire, and 4-wire RTD configurations with PT100 or PT1000 sensors. It features fault detection for open and shorted RTD lines, adjustable resistance settings, and a simple SPI interface for data communication.

1. Define the SPI CS pin and select the “MAX31855,MAX31865” from the list.
2. Define the MISO pin.
3. Define the MOSI pin. This chip implements bidirectional data transfer apart from MAX31855. MISO and MOSI pins are required and should be different.
4. Select the thermocouple type (PT100 or PT1000). Please note that the firmware assumes that you use a 430 Ohm reference resistor for the PT100 and a 4300 Ohm reference resistor for the PT1000.
5. Select wiring type (2 or 4 wires). Do not forget to make the necessary jumpers on the sensor’s board to select the appropriate operation mode.

Note: You can share “MISO”, “MOSI” and “CLK” pins between several sensors.

Zigbee

The firmware sends a temperature in periodic reports as an analog value because the measured value can be outside the range of the standard Zigbee temperature cluster.