Serial

The serial sensor integrationIntegrations connect and integrate Home Assistant with your devices, services, and more. [Learn more] is using the data provided by a device connected to the serial port of the system where Home Assistant is running. With ser2net and socat would it also work for sensors connected to a remote system.

To check what kind of data is arriving at your serial port, use a command-line tool like minicom or picocom on Linux, on a macOS you can use screen or on Windows putty.

sudo minicom -D /dev/ttyACM0

Configuration

To setup a serial sensor to your installation, add the following to your configuration.yamlThe configuration.yaml file is the main configuration file for Home Assistant. It lists the integrations to be loaded and their specific configurations. In some cases, the configuration needs to be edited manually directly in the configuration.yaml file. Most integrations can be configured in the UI. [Learn more] file. After changing the configuration.yamlThe configuration.yaml file is the main configuration file for Home Assistant. It lists the integrations to be loaded and their specific configurations. In some cases, the configuration needs to be edited manually directly in the configuration.yaml file. Most integrations can be configured in the UI. [Learn more] file, restart Home Assistant to apply the changes. The integration is now shown on the integrations page under Settings > Devices & services. Its entities are listed on the integration card itself and on the Entities tab.

# Example configuration.yaml entry
sensor:
  - platform: serial
    serial_port: /dev/ttyACM0

value_template for Template sensor

TMP36

"{{ (((states('sensor.serial_sensor') | float * 5 / 1024 ) - 0.5) * 100) | round(1) }}"

Examples

Arduino

For controllers of the Arduino family, a possible sketch to read the temperature and the humidity could look like the sample below.The returned data is in JSON format and can be split into the individual sensor values using a template.

#include <ArduinoJson.h>

void setup() {
  Serial.begin(115200);
}

void loop() {
  StaticJsonDocument<100> jsonBuffer;

  jsonBuffer["temperature"] = analogRead(A0);
  jsonBuffer["humidity"] = analogRead(A1);

  serializeJson(jsonBuffer, Serial);
  Serial.println();
  
  delay(1000);
}

Devices returning multiple sensors as a text string

For devices that return multiple sensors as a concatenated string of values with a delimiter, (i.e., the returned string is not JSON formatted) you can make several template sensors, all using the same serial response. For example, a stream from the Sparkfun USB Weather Board includes temperature, humidity and barometric pressure within it returned text string. Sample returned data:

$,24.1,50,12.9,1029.83,0.0,0.00,*
$,24.3,51,12.8,1029.76,0.0,0.00,*

To parse this into individual sensors, split using the comma delimiter and then create a template sensor for each item of interest.

# Example configuration.yaml entry
sensor:
  - platform: serial
    serial_port: /dev/ttyUSB0
    baudrate: 9600

template:
  sensor:
    - name: Temperature
      unit_of_measurement: "°C"
      state: "{{ states('sensor.serial_sensor').split(',')[1] | float(default=0) }}"
    - name: Humidity
      unit_of_measurement: "%"
      state: "{{ states('sensor.serial_sensor').split(',')[2] | float(default=0) }}"
    - name: Barometer
      unit_of_measurement: "mbar"
      state: "{{ states('sensor.serial_sensor').split(',')[4] | float(default=0) }}"

Digispark USB Development Board

This blog post describes the setup with a Digispark USB Development Board.