NodeDHT

Utility to retrieve data from DHT11/DHT22 sensor connected to a Raspberry Pi and publish it to MQTT, written in NodeJS, Based on NodeRenogy.

Data can then be surfaced in Home Assistant, or anything else that can read from a MQTT bus.

It currenrly supports a single DHT sensor, with support for multiple sensors coming soon.

This software is licensed under the MIT License.

Compatibility

Any sensor and SBC supported by the node-dht-sensor library.

This is currently DHT11, DHT22 and AM2302 sensors, connected to any Raspberry Pi SBC.

Connecting your Sensor

If you have a bare DHT sensor, you will need a 10k ohm resistor. If you have one on a carrier board, such as commonly available onlinethen you will not need the resistor.

The sensor is powered by 3.3v and has a single data line that is to be connected to a GPIO pin on your Raspberry Pi. The default pin is 4, however you can change this, currently only one sensor is supported.

For further information and diagrams, see here, or if you have a bare sensor, see here

Using the utility

Ideally you would install/run this on a device that has a DHT sensor connected and is running at all times. I use a Raspberry Pi Zero W, which is more than powerful enough for this use case.

This also assumes you have a MQTT broker setup and running already. If you don't want to use MQTT you can output the results to the console. Support for other output methods may come at a later date.

You will first need to ensure you have NodeJS v16+ installed on your device.

NOTE: If you installed a version of node with apt-get on your Pi Zero, please un-install it before installing Node v16.

The Pi Zero/One doesn't have official support for newer version of NodeJS, so follow the instructions here to get it installed.

If you are using a Pi 2 or later, follow the instructions here to install the official NodeSource build.

Once you've got NodeJS installed, then follow the below instructions.

Installation

Clone this repository (or download it) by running;

git clone https://github.com/mickwheelz/NodeJBD.git

Change to the NodeDHT directory and install the dependencies by running the below commands

Change to the directory you cloned the code into: cd NodeDHT
Run installer: npm install
Link command: sudo npm link

Running the utility

Basic Example:

node-dht -g 4 -s 22 -m 192.168.0.10

This would use GPIO pin 4 for a DHT22 sensor and connect to MQTT Broker at 192.168.0.10 with no user/password, publishing to the nodeDHT/state topic every 10s

The utility supports using different polling intervals and topics, as well as MQTT brokers that need authentication, please see below for a full list of options.

These options can also be passed as environment variables, by appending NODEDHT_ to the argument (e.g. NODEDHT_GPIO=4). This is useful when running as a service (see below section).

Argument	Alias	Env Var	Description	Example
--gpio	-g	NODEDHT_GPIO	The GPIO pin your sensor is connected to, defaults to 4	-g 4
--sensorType	-s	NODEDHT_SENSORTYPE	The sensor type as a number e.g DHT22 or DHT11, defaults to 22	-s 22
--mqttbroker	-m	NODEDHT_MQTTBROKER	The address of your MQTT Broker	-m 192.168.0.10
--mqttuser	-u	NODEDHT_MQTTUSER	The username for your MQTT Broker	-u mqttUser
--mqttpass	-p	NODEDHT_MQTTPASS	The password for your MQTT Broker	-p mqttPass
--mqtttopic	-t	NODEDHT_MQTTTOPIC	MQTT topic to publish to defaults to 'NodeJBD'	-t MyTopic
--pollinginterval	-i	NODEDHT_POLLINGINTERVAL	How frequently to poll the controller in seconds, defaults to 10	-i 60
--loglevel	-l	NODEDHT_LOGLEVEL	Sets the logging level, useful for debugging	-l trace
--help	-h		Show help
--version			Show version number

Running as a service

The utility can be configured to run as a service, including on startup.

These instructions are for Rasbpbian, but should work on any Debian based distro (Ubuntu, etc) or any system that uses systemd.

Create a service definition file. This file should contain your required environment variables.

Example:

[Unit]
Description=NodeDHT Service

[Service]
ExecStart=node-dht
Restart=always
User=pi
Group=pi
Environment=PATH=/usr/bin:/usr/local/bin
Environment=NODE_ENV=production
Environment=NODEDHT_GPIO=4
Environment=NODEDHT_MQTTBROKER=192.168.0.10
WorkingDirectory=/home/pi/NodeDHT

[Install]
WantedBy=multi-user.target

Note the Environment=... lines, set any configuration options here such as serial port, MQTT broker, interval, etc.

Name this file nodedht.service and save it in /etc/systemd/system
Run the following commands:

To start the service: systemctl start nodedht
To check the logs/ensure its running: journalctl -u nodedht
To enable the service to run at startup: systemctl enable nodedht

Publishing to MQTT

The utility will publish one topic, with one subtopic on your MQTT Broker. You specify the topic name in the configuration with the default being NodeDHT

The subtopic is <topic>/sensor. This is published at the set interval and contains the values from your sensor.

Example:

{
	"temperature":"8.60",
	"humidity":"99.90",
	"isValid":true,
	"errors":0
}

You can then subscribe the topics with a MQTT client and data as you wish. An example of this would be surfacing it in Home Assistant. See below for more information on how to do that.

Getting data into Home Assistant

The values can be displayed in Home Assistant by adding them as sensors in the configuration.yaml files.

Essentially you just need to extract the values from the JSON payload published to MQTT. For each value you want to use in Home Assistant, add a MQTT sensor entry in your config file.

See below for some examples:

sensor:
- platform: mqtt
    name: "Temperature"
    state_topic: "NodeDHT/sensor"
    value_template: "{{ value_json['temperature'] }}"
    unit_of_measurement: "C"
    device_class: temperature

- platform: mqtt
    name: "Humidity"
    state_topic: "NodeDHT/sensor"
    value_template: "{{ value_json['humidity'] }}"
    unit_of_measurement: "%"
    device_class: humidity

sophienyaa/NodeDHT