home-assistant.io/source/_integrations/firmata.markdown

title	description	ha_category	ha_release	ha_iot_class	ha_codeowners	ha_domain	ha_platforms	ha_integration_type	ha_quality_scale
Firmata	Connect Arduino-compatible boards within Home Assistant	Binary sensor DIY Light Sensor Switch	0.114	Local Push	@DaAwesomeP	firmata	binary_sensor light sensor switch	integration	legacy

Firmata can be used to add analog and digital inputs and outputs to Home Assistant. This allows for buttons, switches, motion detectors, relay control, sensors, potentiometers, dimmers, etc. The integration can currently connect to a Firmata board via serial or serial over USB.

The Firmata protocol is a standard protocol for microcontrollers. Most of these boards support digital and analog inputs and outputs. Arduino and Arduino-compatible microcontroller development boards are the most popular boards to use with Firmata.

There is currently support for the following device types within Home Assistant:

• Binary sensor
• Light
• Sensor
• Switch

Configuration

You will need to upload a Firmata firmware to your board. Please upload any StandardFirmata sketch to your board; please refer to the Arduino documentation for further information for uploading sketches. Firmata is available in the Arduino Library Manager in the Arduino IDE. You may also use a Firmata Express.

To integrate Arduino boards with Home Assistant, add the following section to your {% term "configuration.yaml" %} file:

{% warning %} Firmata does not store the last state across power cycles. This means that with every powerup the pins are set to off/low and after every initialization, they will be set to the default that you have configured in YAML. {% endwarning %}

{% warning %}

Firmata may cycle pins HIGH/LOW during initialization. If your pins should not be accidentally cycled, you may need to modify your Firmtata sketch or if you are using a relay board use an output pin as VCC. See this issue for details: Make initial pin value configurable.

{% endwarning %}

You may configure multiple Firmata boards. Each board has the following options:

{% configuration %} serial_port: description: The port where your board is connected to your Home Assistant host. It is recommended to use the by-id reference (instead of numerical like /dev/ttyACM0 or /dev/ttyUSB0) since these will never change after a reboot. If you are using Home Assistant Operating System, you can find a list of connected serial devices in the Hardware dialog on the {% my hardware title="Settings > System > Hardware" %} panel. required: true type: string serial_baud_rate: description: The baud rate of the Arduino sketch. If you are using Firmata Express, then you do not need to set this option. If you are using the default StandardFirmata, then you should set this to 57600. required: false type: integer arduino_instance_id: description: If you are using Firmata Express, then this should match the instance number that you set in the sketch. required: false type: integer arduino_wait: description: Time in seconds to wait for the Arduino is initially respond. May need to be used for boards that respond slowly at first connection. required: false type: integer sleep_tune: description: Time in seconds to wait for reply from the Arduino after sending a command. Rarely needs to be adjusted. required: false type: float sampling_interval: description: Sampling interval in milliseconds sent to Firmata. Most Firmata sketches will ignore any interval less than 10 milliseconds. required: false type: integer switches: description: Digital high/low outputs to configure required: false type: list keys: name: description: The name of the entity to create in Home Assistant required: true type: string pin: description: The digital or analog pin number on the board. required: true type: [integer, string] pin_mode: description: The digital or analog pin output mode. For switches, this must be set to OUTPUT. No other output modes are currently implemented. required: true type: string initial: description: The initial output of the pin after initialization. Note that this is inverted if negate is enabled. required: false default: False type: boolean negate: description: Flips the output of the digital pin required: false default: False type: boolean lights: description: PWM/Analog outputs to configure required: false type: list keys: name: description: The name of the entity to create in Home Assistant required: true type: string pin: description: The digital or analog pin number on the board. Note that most boards do not support analog or PWM output on all digital and analog pins. required: true type: [integer, string] pin_mode: description: The digital or analog pin output mode. For lights, this must be set to PWM. No other output modes are currently implemented. required: true type: string initial: description: The initial output of the pin after initialization. This should be a Home Assistant-like value from 0 to 255; this value is then plugged into the minimum/maximum scaling (if configured). required: false default: 0 type: integer minimum: description: The minimum PWM/analog value to send (inclusive). This is the lowest allowed value that the pin will output. The Home Assistant brightness value (0 to 255) will be scaled with this value as the lower value of the range. required: false default: 0 type: integer maximum: description: The maximum PWM/analog value to send (inclusive). This is the highest allowed value that the pin will output. The Home Assistant brightness value (0 to 255) will be scaled with this value as the higher value of the range. required: false default: 255 type: integer binary_sensors: description: Digital or analog high/low input to configure required: false type: list keys: name: description: The name of the entity to create in Home Assistant required: true type: string pin: description: The digital or analog pin number on the board. For analog pins the corresponding digital number must be used. Please use the pinout that corresponds to your board. For example, on the Arduino Uno, pin A2 corresponds to the digital pin number 16. required: true type: [integer, string] pin_mode: description: The digital or analog pin input mode. Supported modes are INPUT and PULLUP. Check your board specifications to see which pins have optional internal pullups available. required: true type: string negate: description: Flips the input of the digital or analog pin required: false default: False type: boolean sensors: description: Analog input to configure required: false type: list keys: name: description: The name of the entity to create in Home Assistant required: true type: string pin: description: The analog pin number on the board. This should be in the form A0, A1, etc. required: true type: string pin_mode: description: The analog pin input mode. For sensors, this must be set to ANALOG. No other input modes are currently implemented. required: true type: string differential: description: Minimum difference in value to update. The absolute value of the difference between the old and new value must be greater than or equal to this option for the update to register in Home Assistant. This is set to 40 by default to prevent an unconnected pin from clogging the Home Assistant history with updates. Set this to 1 to register all updates in Home Assistant. Updates are registered as fast as the board can send them (very fast). The minimum value that may be set is 1. required: false default: 40 type: integer {% endconfiguration %}

{% note %} If you double-configure a pin, the integration will fail to configure the second one that it attempts to set up and will log an error. {% endnote %}

{% note %} To invert/negate a light, set the maximum to 0 and the minimum to 255. {% endnote %}

# Example firmata configuration.yaml entry
firmata:
  - serial_port: /dev/serial/by-id/usb-Teensyduino_USB_Serial_358320-if00
    serial_baud_rate: 57600
    switches:
      - name: my_light
        pin_mode: OUTPUT
        pin: 4
        negate: true
      - name: my_other_output
        pin_mode: OUTPUT
        pin: 5
        initial: true
      - name: my_light2
        pin_mode: OUTPUT
        pin: A6
        initial: true
        negate: true
    lights:
      - name: my_dimmable_light
        pin_mode: PWM
        pin: 6
      - name: my_subset_light
        pin_mode: PWM
        pin: 10
        initial: 0
        minimum: 127
        maximum: 200
      - name: my_inverted_light
        pin_mode: PWM
        pin: 11
        minimum: 255
        maximum: 0
    binary_sensors:
      - name: my_motion
        pin_mode: INPUT
        pin: 2
      - name: my_door
        pin_mode: PULLUP
        pin: 3
        negate: true
      - name: my_other_door
        pin_mode: INPUT
        pin: 16   # A2
        negate: true
    sensors:
      - name: my_sensor
        pin: A0
        pin_mode: ANALOG
        differential: 40