MAX31865 Platinum RTD Temperature Sensor

The max31865 temperature sensor allows you to use your max31865 RTD temperature sensor (datasheet) with ESPHome

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MAX31865 Sensor. Image by Adafruit

As the communication with the MAX31865 is done using SPI, you need to have an spi bus in your configuration with both miso_pin and mosi_pin set.

  • VIN connects to 5V (3V3 will output 3.3V), or directly connect 3V3 to 3.3V

  • 3Vo is not used by ESPHome

  • GND connects to ground

  • CLK connects to the SPI clk_pin

  • SDO connects to the SPI miso_pin

  • SDI connects to the SPI mosi_pin

  • CS connects to a free GPIO pin

  • RDY is not used by ESPHome

# Example configuration entry
spi:
  miso_pin: D0
  mosi_pin: D1
  clk_pin: D2

sensor:
  - platform: max31865
    name: "Living Room Temperature"
    cs_pin: D3
    reference_resistance: 430 Ω
    rtd_nominal_resistance: 100 Ω

Configuration variables:

  • name (Required, string): The name for the temperature sensor.

  • cs_pin (Required, Pin Schema): The Chip Select pin of the SPI interface.

  • update_interval (Optional, Time): The interval to check the sensor. Defaults to 60s.

  • reference_resistance (Required, float): Reference resistor on the PCB. Adafruit’s PT100 (#3328) uses 430 Ω, their PT1000 (#3648) uses 4300 Ω.

  • rtd_nominal_resistance (Required, float): Nominal resistance of the RTD at 0°C. PT100 is 100 Ω, PT1000 is 1000 Ω.

  • mains_filter (Optional, string): The mains power frequency to reject (50 Hz or 60 Hz). Defaults to 60 Hz.

  • rtd_wires (Optional, int): The number of RTD wires. Be sure to solder board jumpers to match! Defaults to 4.

  • spi_id (Optional, ID): Manually specify the ID of the SPI Component if you want to use multiple SPI buses.

  • id (Optional, ID): Manually specify the ID used for code generation.

  • All other options from Sensor.