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.