Joystick Support #370

Add support for an analog joystick component to the Pi4Micronaut library.

Component Behavior

The joystick component should allow users to read directional input, with the x-axis and y-axis each being read. The class should also be able to read when the joystick is being pressed down. It should expose methods to query its state.

You can find example circuit diagrams and code at the Sunfounder Raphael Kit documentation. You can use this to help you write the helper class and wire up your components for hardware testing and writing the documentation.

Prerequisite:
The ADC component refactoring issue (#380) is a prerequisite for this work, as integrating the potentiometer requires reliable analog-to-digital conversion.

Since this requires an ADC converter, the joystick helper class should take in an ADC converter into its constructor. It will then call the ADC's readValue method; it will read from the ADC's channel 0 to get the x-axis value, and from channel 1 to get the y-axis value.

Whether the joystick is pushed down will be a simple DigitalInput read, akin to our push button component.

Acceptance Criteria

Helper Class

A helper class is needed to implement the low-level interactions with the component, and the methods that developers will call when using our library.

• Class is written in the appropriate subfolder of pi4micronaut-utils/src/main/java/com/opensourcewithslu.
• Class fully implements functionality for the component using GPIO digital input and an ADC component.
• Class logs all important changes in state and behavior.
• Class handles errors gracefully and provides helpful error messages.

Controller Class

A controller class is needed to provide an example of how developers can use our helper class. This will be used in our documentation.

• Class is written in the appropriate subfolder of components/src/main/java/com/opensourcewithslu/components/controllers.
• The pinout needed for wiring up the component is documented in components/src/main/resources/application.yml, following the template set by the rest of the file. It will have an ADC configuration under the spi section, and a configuration under the digital-input section for reading whether the joystick is pushed down.
• Controller class has appropriately named API endpoints to show off all functionality of the component.

Tests

Software unit tests are needed to verify that the helper class functions correctly.

• Tests are written using the Java JUnit Jupiter framework in the appropriate subfolder of pi4micronaut-utils/src/test/java/com/opensourcewithslu.
• Test cases are written to validate all implemented behavior.
• Tests handle edge cases.
• Tests validate all cases where a method should fail, and that appropriate error messages are provided.
• Tests validate that appropriate log messages are sent by each relevant method.
• All tests pass.

Documentation

• Documentation is written in written as an AsciiDoc file in the appropriate subfolder of pi4micronaut-utils/src/docs/asciidoc/components.
• Includes component description, including the basic function of the component and a description of all important features of the component.
• Provides a complete list of needed components and materials for setting up the breadboard circuit.
• Provides complete detailed instructions for assembling the breadboard circuit.
• Includes a circuit diagram.
• Includes a schematic diagram.
• Includes the GPIO pinout configuration needed for in the application.yml for the breadboard circuit. This should match the relevant parts of the application.yml file in the components project.
• Includes (via dynamic linking) the example controller in the components project.