The Arduino device family are microcontroller boards that are often based on the ATmega328 chip. They come with digital input/output pins (some can be used as PWM outputs), analog inputs, and a USB connection. The equipment depends on the type of the board. The most common ones are the Arduino Uno and the Arduino Leonardo with 14 digital input/output pins and 6 analog input pins.

There are a lot of extensions (so-called shields) available. Those shields can be plugged-in into the existing connectors and stacked on top of each other. This makes it possible to expand the capabilities of the Arduino boards.

The arduino component is designed to let you use a directly attached board to your Home Assistant host over USB.


You need to have the Firmata firmware on your board. Please upload the StandardFirmata sketch to your board; please refer to the Arduino documentation for further information.

To integrate an Arduino boards with Home Assistant, add the following section to your configuration.yaml file:

# Example configuration.yaml entry
  port: /dev/ttyACM0

Configuration Variables


(string)(Required)The port where your board is connected to your Home Assistant host. If you are using an original Arduino, the port will be named ttyACM* otherwise ttyUSB*.

The exact number can be determined with the command shown below.

$ ls /dev/ttyACM*

If that’s not working, check your dmesg or journalctl -f output. Keep in mind that Arduino clones are often using a different name for the port (e.g., /dev/ttyUSB*).

A word of caution: The Arduino boards are not storing states. This means that with every initialization the pins are set to off/low.

Add the user who is used to run Home Assistant to the groups to allow access to the serial port.

$ sudo usermod -a -G dialout,lock $USER