C++ GPIO

[stephenhensley]

This is essentially a duplicate of the work done in #354 except that it preserves the C-style GPIO API. Idea being that we'll add planned deprecation of the current usage without breaking any code. Some time next year we'll remove the old C style, but this will allow for a gradual replacement.

We'll need to go through and adapt the rest of the library to use the new Pin type instead of the old, dsy_gpio_pin, but it doesn't have to happen right away. We can do that as gradually as we need to. I've added an operator for a conversion to the old type. So the new struct can already be used anywhere that the old one was used without any other changes necessary.

List of changes:

• Add new Pin structure to replace old c-style dsy_gpio_pin
• Add new GPIO class with C++ API, and multiple initialization options.
• Added comments to all old dsy_gpio_pin functions noting that code should migrate to using the new Pin struct.
• Added daisy::seed namespace containing constexpr Pin mappings for the entire SOM.
  • A namespace was used instead of having these be DaisySeed members to allow for simplistic, Arduino-like syntax when using the pins. (i.e. a_gpio.Init(D0, GPIO::Mode::OUTPUT);
  • There was a brief discussion about putting the DaisySeed inside of this namespace, but this would cause a breaking change. So we will put off doing any namespace reorganization of existing board-classes, etc. until a later time.
• Somewhat out of the scope of the PR: Moved contents of DaisySeed::Configure to the DaisySeed::Init function, making the Configure an empty function. The function was left in place for now to prevent any breaking changes.

These changes stage a few things for future removal. At some point likely Q2-Q3 of 2022 we'll do more substantial update that actually removes these old mechanics, and cleans up the library a bit.

For now we're trying to improve accessibility, and ease of use without breaking existing code.

[github-actions[bot]]

Unit Test Results

    1 files  ±0    16 suites  +1   0s :stopwatch: ±0s 145 tests +4  145 :heavy_check_mark: +4  0 :zzz: ±0  0 :x: ±0 

Results for commit e3a7d532. ± Comparison against base commit 2d3f3d00.

:recycle: This comment has been updated with latest results.

[stephenhensley]

Found something pretty funky: GPIOPort::PI is a big red flag because... well.. it's PI.. 🥧

So we'll loop back around on the naming -- leading contender for the port names now is PORTA, PORTI, etc.