periph-servo-pca9685 modular component

This module implements the Viam servo API in a periph-servo-pca9685 model.

With this model, you can control servos connected to PCA9685 channels using the periph.io library.

Setup

Navigate to the CONFIGURE tab of your machine's page.

Click the + button, select Component or service, then select the servo / periph-servo-pca9685 model provided by the module.

Click Add module, enter a name for your servo, and click Create.

Configure your periph-servo-pca9685 servo

On the new component panel, copy and paste the following attribute template into your servo's Attributes box:

{
  "i2c_bus": <string>,
  "i2c_addr": <string>,
  "channel": <int>,
  "frequency_hz": <int>,
  "min_angle_deg": <int>,
  "max_angle_deg": <int>,
  "starting_position_deg": <int>,
  "min_width_us": <int>,
  "max_width_us": <int>
}

Attributes

The following attributes are available for periph-servo-pca9685 servos:

Name	Type	Inclusion	Description
i2c_bus	string	Optional	The name or number of the I2C bus to which the PCA9685 is connected. Default: "0".
i2c_addr	string	Optional	The I2C address of the PCA9685. Can be formatted as hex (0x) or base 10. See this guide for how to detect i2c devices. i2cdetect displays the hex formatted value. Default: "0x40".
channel	int	Optional	The channel (0-15) to which the servo is connected. Default: 0.
frequency_hz	int	Optional	The frequency in Hz of the servo. See the servo datasheet. Default: 50.
min_angle_deg	int	Optional	The minimum angle in degrees to which the servo will be allowed to move. Default: 0.
max_angle_deg	int	Optional	The maximum angle in degrees to which the servo will be allowed to move. Default: 180.
starting_position_deg	int	Optional	When the servo is initiated, it will move to this position (in degrees). Default: 0.
min_width_us	int	Optional	The minimum duty cycle width in microseconds. See the servo datasheet. Default: 500.
max_width_us	int	Optional	The maximum duty cycle width in microseconds. See the servo datasheet. Default: 2500.

Example Configuration

{
  "i2c_bus": "0",
  "channel": 15
}

Development

To release a new version of this module, this repo uses the Viam build-action to build the module in Viam's cloud infrastructure and deploy the new version based on a tagged release.

To kick off a deployment:

1. Tag the release commit with the new module version and push it to the repo
2. Create a release based on that tag

Within a couple of minutes, the new module version will be published to the Viam registry.

If there is an issue with the action and a manual release is required:

1. Authenticate the Viam CLI:

   viam auth login

2. Start a remote build for the new module version

   viam module build start --version <version>