Async thoughts

Are these good async demos?

• An async button or two, that do something like cycle colors or turn off the LEDs
• an async SPI driver that handles sending the WS2812 commands
• An async i2c port listening for color/brightness/mode values for 2 LEDs

I2C port

• Event driven: We are responding to incoming commands
  • Have a couple different API items:
    • Mode (off, solid, blink, updown)
    • Brightness
    • Color
  • Have two register sets
  • Could benefit from interrupts
• Outputs...?
  • Event stream to another Cassette?
  • Poll API for current state?
  • Pub Sub?

Button

• Purely event driven
  • Basically this is just the exti interrupt? Or polling I guess?
• Outputs...?
  • Event stream?
  • Poll API?

SPI

• Really just sequencing outputs
• Could have it's own state for sequencing?
• Could potentially benefit from DMA/interrupts?
• Could potentially allow for multiple concurrent senders?

Approaches

Brain Default

• RTIC
• EXTI interrupt task
• SPI task
  • Mostly for DMA reload?
• I2C task
  • emit changes/updates?
• IDLE task
  • Doing periodic updates

???

• EXTI future
  • allows for waiting on events like transitions?
  • async task that awaits on futures, and sends messages to N channels?
• SPI/smartled task
  • Listens for messages to send (but how does it know to wake up?)
  • Calls future enabled SPI driver
  • Has some sort of "current status" interface?
• I2C Peripheral
  • pretty much all in the interrupt?