- Move typelevel interrupts to a special-purpose mod: `embassy_xx::interrupt::typelevel`.
- Reexport the PAC interrupt enum in `embassy_xx::interrupt`.
This has a few advantages:
- The `embassy_xx::interrupt` module is now more "standard".
- It works with `cortex-m` functions for manipulating interrupts, for example.
- It works with RTIC.
- the interrupt enum allows holding value that can be "any interrupt at runtime", this can't be done with typelevel irqs.
- When "const-generics on enums" is stable, we can remove the typelevel interrupts without disruptive changes to `embassy_xx::interrupt`.
Assert "tx_empty" interrupt a little early so there's time to wake up
and start refilling the fifo before it drains. This avoids stalling the
i2c bus if the tx fifo completely drains.
This is an interrupt-driven async i2c master implementation. It makes as
best use of the RP2040's i2c block's fifos as possible to minimize
interrupts.
It implements embedded_hal_async::i2c for easy interop.
WIP async impl
