HX711 Load Cell Amplifier

The hx711 sensor platform allows you to use your HX711 load cell amplifier (datasheet, Sparkfun) with ESPHome

../../_images/hx711-full.jpg

HX711 Load Cell Amplifier. Image by Sparkfun licensed and re-distributed under CC BY 2.0.

Connect GND to GND, VCC to 3.3V and the other three MISO (or SO for short), CS and CLOCK (or SCK) to free GPIO pins.

# Example configuration entry
sensor:
  - platform: hx711
    name: "HX711 Value"
    dout_pin: D0
    clk_pin: D1
    gain: 128
    update_interval: 60s

Configuration variables:

  • name (Required, string): The name for the load cell sensor.
  • dout_pin (Required, Pin Schema): The DOUT (or DAT) pin.
  • clk_pin (Required, Pin Schema): The CLK pin.
  • update_interval (Optional, Time): The interval to check the sensor. Defaults to 60s.
  • id (Optional, ID): Manually specify the ID used for code generation.
  • All other options from Sensor.

Converting Units

As the HX711 does not have any calibration data, you have to convert the measurement to units yourself. To calibrate the sensor:

  1. Place a zero load or a known mass on the sensor, for example 0kg
  2. Wait for the data to arrive in the logs and write down the value. For example 120.
  3. Place another (different) known mass on the sensor, for example 1kg
  4. Again wait for the data to arrive and note the value, for example 810.

Once you’ve done those steps, you can use the calibrate_linear filter to map the incoming value to the calibrated one:

# Example configuration entry
sensor:
  - platform: hx711
    # ... Other HX711 options
    filters:
      - calibrate_linear:
          - 120 -> 0
          - 810 -> 1
    unit_of_measurement: kg

Replace the masses and values 120.0, 810.0, etc with your values.