VirtualPins

Hi!

I have and enhancement proposal to do small changes in the wiring_digital file and pins_arduino pin mapping, fully preserving compatibility, virtualizing the pins concept and do media (SPI,I2C, etc..) abstraction.
With minimal impact on existing function performance. The existing checks can work on an extended pin map and only adding an if, comparing pin number with a constant to existing functions (digital read/write).

In case of mapping to a virtual pin then the "content" is sent over an SPI or I2C (according to the map).

with this changes, libraries like LiquidCristal wouldn't have to be rewritten to control the same LCD's wired over SPI or I2C.

There are a LOT of advantages beside the mentioned one, but just for that I thinks it worth the effort considering the minimal impact it has.

I've done the implementation and some tests, available here for testing/appreciation:

https://github.com/neu-rah/VirtualPins

but I wish to put it here for discussion first and to get some advice on how should I proceed.

1. do a pull request with the changes to the arduino environment.
2. implement an alternative core and board that use virtual pins by duplicating some of the existing boards and pointing them to the alternative core.

waiting for feedback.

thanks.

_P.S. this was once done (in bad timing, to and older IDE) but now I'm available again and ported it to 1.8.3_

Start by reviewing the wiring_digital file and pins_arduino pin mapping, then compare the proposed behavior with the implementation and tests in the linked VirtualPins repository. The proposal is complete when existing pin APIs remain compatible, virtual mappings can carry content over SPI or I2C, and performance impact is demonstrated as minimal.

Written by the indexing model from the issue text.