Edit

Configure an Ultrasonic Sensor (viam-micro-server)

Configure an ultrasonic sensor to integrate the HC-S204 ultrasonic distance sensor into your machine. Physically connect your sensor to your microcontroller and power both on. Then, configure the sensor:

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 sensor type, then select the ultrasonic model. Enter a name or use the suggested name for your sensor and click Create.

Creation of a ultrasonic sensor in the Viam app config builder.

Edit and fill in the attributes as applicable to your sensor, according to the table below. Although "board" is marked as required in viam-server, it is not required for viam-micro-server usage.

Attributes template
Attributes example

{
  "trigger_pin": "<pin-number>",
  "echo_interrupt_pin": "<pin-number>"
}

{
  "trigger_pin": "15",
  "echo_interrupt_pin": "18"
}

{
  "components": [
    {
      "name": "<your-ultrasonic-sensor-name>",
      "model": "ultrasonic",
      "type": "sensor",
      "namespace": "rdk",
      "attributes": {
        "trigger_pin": "<pin-number>",
        "echo_interrupt_pin": "<pin-number>"
      },
      "depends_on": []
    }
  ]
}

{
  "components": [
    {
      "name": "my-ultrasonic-sensor",
      "model": "ultrasonic",
      "type": "sensor",
      "namespace": "rdk",
      "attributes": {
        "trigger_pin": "15",
        "echo_interrupt_pin": "18"
      },
      "depends_on": []
    }
  ]
}

The following attributes are available for ultrasonic sensors:

Attribute	Type	Required?	Description
`trigger_pin`	string	Required	The GPIO number of the board’s GPIO pin that you have wired to the trigger pin of your ultrasonic sensor.
`echo_interrupt_pin`	string	Required	The GPIO number of the board’s GPIO pin that you have wired to the echo pin of your ultrasonic sensor. Please note that unlike the RDK ultrasonic sensor, you must not use a named pin associated with a digital interrupt configured on your board: it will not (currently) work.
`timeout_ms`	int	Optional	Time to wait in milliseconds before initiating a timeout when requesting readings from your ultrasonic sensor. Default: `50` Max: `100`

Test the sensor

After you configure your sensor, open the sensor’s TEST panel on the CONFIGURE or CONTROL tabs. To access detailed readings from your sensor, click on the Get Readings button.

Troubleshooting

If your sensor is not working as expected, follow these steps:

Check your machine logs on the LOGS tab to check for errors.
Review this sensor model’s documentation to ensure you have configured all required attributes.
Check that any wires are securely attached to the correct pins, if appropriate.
Click on the TEST panel on the CONFIGURE or CONTROL tab and test if you can use the sensor there.

If none of these steps work, reach out to us on the Community Discord and we will be happy to help.

Next steps

Check out the sensor API or check out one of these guides:

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