Configure an Incremental Encoder (viam-micro-server)

Use the incremental encoder model to configure a quadrature encoder.

Configuring an incremental encoder requires specifying the pin numbers of the two pins on the board to which the encoder is wired. These two pins provide the phase outputs used to measure the speed and direction of rotation in relation to a given reference point.

Navigate to the CONFIGURE tab of your machine’s page in the Viam app. Click the + icon next to your machine part in the left-hand menu and select Component. Select the encoder type, then select the incremental model. Enter a name or use the suggested name for your encoder and click Create.

Configuration of an incremental encoder in the Viam app config builder.

Fill in and edit the attributes as applicable.

{
  "name": "<your-encoder-name>",
  "model": "incremental",
  "type": "encoder",
  "namespace": "rdk",
  "attributes": {
    "board": "<your-board-name>",
    "a": "<your-first-pin-number>",
    "b": "<your-second-pin-number>"
  }
}

{
  "components": [
    {
      "name": "myEncoder",
      "model": "incremental",
      "type": "encoder",
      "namespace": "rdk",
      "attributes": {
        "board": "local",
        "a": "13",
        "b": "11"
      }
    }
  ]
}

The following attributes are available for incremental encoders:

NameTypeRequired?Description
boardstringRequiredThe name of the board to which the encoder is wired.
astringRequiredGPIO number of one of the pins to which the encoder is wired
bstringRequiredGPIO number of the second board pin to which the encoder is wired

Test the encoder

Once your encoder is configured and connected, open the encoders’s TEST panel on the CONFIGURE or CONTROL tabs. The ticks count is displayed. Try moving the encoder (for example, by turning a motor it is attached to) and check whether the count increases as expected.

Encoder test panel.

If the encoder does not appear on the TEST panel, or if you notice unexpected behavior, check your machine’s LOGS tab for errors, and review the configuration.

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