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Homebridge Plugin for DHT22

This is a Homebridge plugin for DHT22 temperature and humidity sensor, working on the Raspberry Pi 3.

It uses the BCM2835 GPIO library.

Configuration

Before running this plugin, you must add the homebridge user to the gpio group so Homebridge can access the GPIO interface. sudo adduser homebridge gpio

Field name Description Type / Unit Default value Required?
name Name of the accessory string — Y
pin DHT22 data pin number, with BCM naming scheme int 4 N
refreshPeriod Time between each refresh of data int / seconds 60 N
maxRetries Number of times to retry if failed to fetch data from sensor int 50 N
maxTempDelta Maximum allowable temperature change between each reading float / deg C 5 N
maxHumDelta Maximum allowable humidity change between each reading float / % 5 N
tempOffset Number of degrees C to add to each temperature reading float / deg C 0 N
humOffset Percentage to add to each humidity reading float / % 0 N
enableFakeGato Enable storing data in Eve Home app bool false N
fakeGatoStoragePath Path to store data for Eve Home app string (fakeGato default) N
enableMQTT Enable sending data to MQTT server bool false N
mqttConfig Object containing some config for MQTT object — N

The mqttConfig object is only required if enableMQTT is true, and is defined as follows:

Field name Description Type / Unit Default value Required?
url URL of the MQTT server, must start with mqtt:// string — Y
temperatureTopic MQTT topic to which temperature data is sent string dht22/temeprature N
humidityTopic MQTT topic to which humidity data is sent string dht22/humidity N

Example Configuration

{
  "bridge": {
    "name": "Homebridge",
    "username": "XXXX",
    "port": XXXX
  },

  "accessories": [
    {
      "accessory": "DHT22",
      "name": "Office DHT22",
      "pin": 4,
      "refresh": 60,
      "maxRetries": 50,
      "enableFakeGato": true,
      "enableMQTT": true,
      "mqtt": {
        "url": "mqtt://192.168.0.38",
        "temperatureTopic": "dht22/temperature",
        "humidityTopic": "dht22/humidity"
      }
    },
  ]
}

Project Layout

  • All things required by Node are located at the root of the repository (i.e. package.json and index.js).
  • The rest of the code is in src, further split up by language.
    • c contains the C code that runs on the device to communicate with the sensor. It also contains a simple program to check that the sensor is connected and attempt to read from it.
    • binding contains the C++ code using node-addon-api to communicate between C and the Node.js runtime.
    • js contains a simple project that tests that the binding between C/Node.js is correctly working.