DeviceApiTester is a sample application primarily for testing the GPIO drivers and surrounding infrastructure. After publishing the app to a target device, simply run DeviceApiTester to see the command line syntax.

One notable difference between the samples and real-world usage is that, because this sample allows for changing the GPIO driver from the command line, the base GpioCommand class has the CreateGpioController method. In practice, though, you would simply create the GpioController directly:

using (var gpio = new GpioController())
{
    ...
}

Similarly, the same note applies to the SPI, I2C, and PWM test commands.

To simplify the command line parsing and adding new command, this application uses the CommandLineParser package. This simple parsing framework automatically creates help text based on attributes of the classes in the Commands folder, such as the GpioBlinkLed class.

Each of the commands has an ExecuteAsync or Execute method at the top of the class, which is where the sample usage is actually demonstrated. The automatic properties of the class represent options for the command, which are set by the command line parsing framework. The attributes on the command and its properties are used to setup the command line.

1. See a list of all commands:

   DeviceApiTester help

2. Show the gpio-button-event command's syntax:

   DeviceApiTester help gpio-button-event

3. Run the command with required parameters:

   DeviceApiTester gpio-button-event --button-pin 5 --led-pin 6

4. Run the command with many optional parameters:

   DeviceApiTester gpio-button-event --scheme Board --button-pin 29 --pressed-value Falling --led-pin 31 --on-value Low --driver RPi3

5. Run the command with many optional parameters using single-characters options:

   DeviceApiTester gpio-button-event -s Board -b 29 -p Falling -l 31 --on-value Low -d RPi3

1. Derive a new class from one of the protocol base command classes, e.g., GpioCommand, I2cCommand, SpiCommand. Deriving from one of these classes automatically gives your command the switches necessary to setup that type of connection.

   namespace DeviceApiTester.Commands.I2c
   {
       public class MyCommand : I2cCommand
       {
       }
   }

   • It's easiest to begin by copying one of the existing commands.

   • Keep the new command class within the folder for connection type:

     Commands/Gpio, Commands/I2c, Commands/Spi.

2. Add or modify the Verb attribute to describe the command:

   [Verb("i2c-my-command", HelpText = "This command does something with an I2C connection.")]

   • Prefix the command's verb with its connection type: gpio-, i2c-, spi-

3. Implement either the ICommandVerb or ICommandVerbAsync interface on your command class:

   public class MyCommand : I2cCommand, ICommandVerb
   {
       public int Execute()
       {
           Console.WriteLine($"BusId={BusId}, DeviceAddress={DeviceAddress}");
           return 0;
       }
   }

   or

   public class MyCommand : I2cCommand, ICommandVerbAsync
   {
       public async Task<int> ExecuteAsync()
       {
           Console.WriteLine($"BusId={BusId}, DeviceAddress={DeviceAddress}");
           await Task.Delay(500);
           return 0;
       }
   }

4. Add automatic properties for command options:

   [Option('c', "cool-option", HelpText = "A cool option argument", Required = false, Default = 0)]
   public int CoolOption { get; set; }

5. Use the properties in your execution:

   public int Execute()
   {
       Console.WriteLine($"CoolOption={CoolOption}, BusId={BusId}, DeviceAddress={DeviceAddress}");
       ...
   }

6. Deploy and run:

   DeviceApiTester help
   DeviceApiTester help i2c-my-command
   DeviceApiTester i2c-my-command --cool-option 42