AhmsVille Dial 2 Firmware

Concept

This firmware is driven by a cooperative task scheduler (https://github.com/arkhipenko/TaskScheduler). delay statements are omitted as much as possible in favor of the scheduling of tasks.

Each task takes care of a particular workload either related to the device as a whole or a particular sensor.

Furthermore, tasks are kept hardware-agnostic. Abstract classes / interfaces are used to encapsulate the functionality of actual hardware. This is done in order to make the code testable.

In the end the value change of each sensor is written as often as defined to the Serial port for e.g. an userspace driver to consume.

Thanks

This piece of software was only possible due to incredible work from Ahmed Oyenuga as well as all the respective developers of the open-source libraries.

setup() function

In this function the device is configured and calibrated as needed.

Each DialTask has an onSetup() function, which is executed during the device set up and ensures, that this task is ready to run its onCallback() function when scheduler.execute() is run (in the loop() function of the main script).

loop() function

In this function only scheduler.execute() is run, because the task scheduler keeps track of which task gets assigned processing cycles next. Even though there can be "high priority" tasks, these are not used.

Whenever a particular task is scheduled to run, its onCallback() function is called.

interrupting functions

A couple of sensors interrupt the program whenever a value change (rise, fall, change etc.) is determined. For example each MacroKey interrupts the program and writes its value change to the Serial port.

This project is made using CLion and the PlatformIO plugin.

It currently is designed for the AhmsVille Dial 2 Absolute Edition. It contains a program, that is supposed to be compiled and uploaded onto the AhmsVille Dial 2 AE Arduino Zero via the Native USB Port.

Serial port input

Some tasks handle user-input. InputProcessorTask parses messages from the Serial port and each individual task handles its own messages.

Invalid messages are cleared by the MessagesCleanerTask after they become invalid (which is after some milliseconds or if a task set the validity to false).

The currently valid input format is JSON. See individual tasks for the JSON structure.

Serial port output

Some tasks output their sensor values to the Serial port. The output is in JSON.

Tasks output their values and the time (millis()) when they occurred.

Furthermore, tasks can also output error statements in JSON, usually describing any of the possibly anticipated error messages. These can easily be processed by a userspace driver.

Notes

• This documentation is always subject to change as implementation progresses.
• Ensure, that there is always a delay(5000) or more in the setup() function. If your implementation crashes, you will have 5 seconds to upload a new, e.g. empty application to recover.