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Home Assistant

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Kit

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PM2.5 Air Quality Kit (SHT30)

Unit PoE Cam W v1.1 Kit

Sensor

Unit ENV-IV

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Unit MQ

Unit AMeter

Unit VMeter

Unit KMeter-ISO

Light

Atom-Lite RGB Light

Unit AMeter Home Assistant Integration

Unit AMeter is an ammeter designed for real-time current monitoring. Internally it uses a 16-bit ADC converter ADS1115 and communicates over I2C (0x48).

Note
Because Unit VMeter is only a standalone sensor platform, an additional host device (such as Atom Lite, Core2, CoreS3, etc.) is required to integrate it into Home Assistant

Get the latest ADS1115 configuration from ESPHome

Configure the sensor

You need to enable the I²C component in your ESPHome configuration:

yaml
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# Example configuration entry for ESP32
i2c:
  sda: GPIOXX
  scl: GPIOXX
  scan: true

The GPIO pins here will vary depending on the host device used. For example, when using Atom Lite as the host:

yaml
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# I2C Bus on Grove Port (HY2.0-4P)
i2c:
  sda: GPIO26
  scl: GPIO32

Unit AMeter configuration example

  • First, configure the base component ADS1115
yaml
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ads1115:
  - address: 0x48

sensor:
  - platform: ads1115
    multiplexer: "A0_A1"
    gain: 0.256
    sample_rate: 128
    name: "Unit AMeter A0_A1 Ref"
    id: diff
    update_interval: 10s
Tip
Unit AMeter only uses AIN0 and AIN1 channels, so you can use up to 3 multiplexer options: "A0_A1", "A0_GND", "A1_GND"; for current measurement this configuration uses only A0_A1.
  • Configure EEPROM to read calibration parameters and create custom data using a Template sensor
yaml
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i2c_device:
  id: eeprom
  address: 0x51

sensor:
  # Previous ads1115 declarations
  ...
  - platform: template
    name: "Input Current"
    id: input_cur
    unit_of_measurement: "A"
    icon: "mdi:current-dc"
    accuracy_decimals: 2
    update_interval: 10s
    lambda: |-
      float d = id(diff).state;

      if (isnan(d)) return NAN;

      const float PRESSURE_COEFF = 0.05f;

      const uint8_t EEPROM_REG = 0xF8;

      uint8_t calib[8];
      uint16_t hope, actual;

      if ( id(eeprom).read_register(EEPROM_REG, calib, 8) != i2c::ERROR_OK ) {
        ESP_LOGD("ameter.sensor", "Failed to read from EEPROM..");
        return NAN;
      }

      uint8_t xor_result = 0x00;

      for (uint8_t i = 0; i < 5; i++) {
          xor_result ^= calib[i];
      }

      if (xor_result != calib[5]) {
          return NAN;
      }

      hope   = (calib[1] << 8) | calib[2];
      actual = (calib[3] << 8) | calib[4];

      float calibration_ratio = (float)hope / actual;

      ESP_LOGD("ameter.sensor", "Factory calibration factor: %f", calibration_ratio);

      float ain = - d / PRESSURE_COEFF;

      ain = ain * calibration_ratio;
    
      return ain;

When reading the EEPROM, you need to change the EEPROM_REG read address in the lambda expression according to the gain value set for ADS1115:

c++
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// In lambda expression
// remember to change the 'EEPROM_REG' if you changed the 'gain'
// for an example, when 'gain' is 0.256
const uint8_t EEPROM_REG = 0xF8;
ADS1115 Gain EEPROM Data Register Max Input Current (theory)
6.144 0xD0 -
4.096 0xD8 -
2.048 0xE0 -
1.024 0xE8 -
0.512 0xF0 10 A
0.256 0xF8 5 A

The recommended gain value is 0.256, resolution 0.3mA. Only one of AIN0 or AIN1 can be measured; do not connect inputs to both channels.

WARNING
The product's designed optimal measurement range is ±4V and it has a built-in fuse. Currents exceeding 4A will trigger the fuse — do not input currents beyond this range, and avoid open-circuit conditions to prevent device damage. The EEPROM (0x51) contains factory calibration parameters; do not perform write operations to the EEPROM, otherwise the calibration data may be overwritten and measurements may be inaccurate.

Add the sensor to Home Assistant

After adding it to the Dashboard, you can view the sensor data in Home Assistant

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