Portduino

This is an experiment with getting the Arduino API so that it can run on top of the Linux OS.

You don't want this yet ;-)

Description

Someone wanted Meshtastic for a new linux based tablet, so I'm making a new new thing (which might be useful for other projects).

I'm going to implement the arduino libs/API layer and support the following device level access from (blessed) user-space regular apps:

• SPI
• I2C
• Interrupt handlers (they won't know they are actually in userspace)
• GPIO control
• Serial (but actually being done through any Unix file descriptor - so could be pipes/files/devices)
• Any of the above can be implemented by particular 'Drivers' - so either the mainboard kernel-space SPI/I2C controller or via external USB to SPI/I2C/GPIO adapters

(This is the portion of Arduino that my project needs - and I bet this is sufficient for most Arduino projects)

Secondary goals

Eventually a variant of this library will allow removing SoftDevice from the NRF52 targets - for a dramatic flash/RAM savings (this will be built on top of Apache MyNewt)

TODO (short term)

• Prop to dev branch
• Implement Thread and Lock
• Implement Interrupt dispatching
• Allow multiple GPIO implementations (on a per GPIO basis) - lets user mix and max sim pins, with motherboard pins, with USB pins
• Add platform-arm
• Add CS341SPI driver (USB to SPI chip)
• Implement InterruptHandler via threads
• Have meshtastic talk to radio over that chip

TODO (long term)

• Change PORTDUINO def to PORTDUINO and PORTDUINO_Linux_x86_64
• Figure out why -Os breaks the executable and what part of platformio is setting that (it comes in before the platform stuff even)
• Change to use platform-native
• Split out threading library from meshtastic
• Implement a tiny rasberry pi example that blinks a LED
• Show that same example blinking a sim LED
• Announce and request feedback
• Add a scripting API for doing button presses, reading current screen contents, etc...
• Use exceptions on linux
• Split out logging library
• Change into an actual real platformio "framework"
• Send in platformio PR
• Let LinuxSerial go places other than stdout
• Make a variant that runs on top of MyNewt
• Unify Thread/Semaphore/TypedQueue wrappers with the FreeRTOS versions

Done

• DONE Use https://github.com/arduino/ArduinoCore-nRF528x-mbedos as a model?
• DONE Get hello world building as an app
• DONE Add SimGPIO
• DONE Add SimSPI
• DONE Add SimI2C
• DONE Add Serial
• DONE Build and run Meshtastic on top of this new framework (stubbed tho)
• Implement printf
• Implement random
• Implement FS
• Turn SPI probing on for RF95
• Fix NRF52 build - "pio update" is a clue