Add gpiote module to nrf52-hal-common

[chris-ricketts]

It would be nice to have a safe, ergonomic API to setup events and tasks using the GPIOTE module.

I have an example of how the PAC can be used directly, tested out on the nrf52 dev kit.

I'm up for giving this a go.

I'm guessing it's going to be kind of similar to the gpio module but with more layers. Also I'm wondering about the best way to handle the multiple channels.

It definitely needs a typestate to indicate whether an event pin is configured as pullup or pulldown as a floating pin had me scratching my head for a while.

Does anyone have any hints or implementations they know of in other HAL crates that deal with similar functionality?

[hannobraun]

Another usage example: https://github.com/braun-embedded/rust-dw1000/blob/34df744e4d0b83602191f7a48dfd4951ec143655/dwm1001/src/lib.rs#L884

[jamesmunns]

@chris-ricketts have you made any progress on this so far?

[chris-ricketts]

@jamesmunns I haven't got round to starting this yet - would you like to take it on?

[kalkyl]

Has anyone started on this yet?
I've been using the gpiote quite a lot and have written a module to help with that. Should i open a PR with what i have where we could discuss and agree on an API?

[jonas-schievink]

@kalkyl Go ahead! I always find it easier to discuss working code rather than ideas.

[kalkyl]

PR #167
Example:
https://github.com/kalkyl/nrf-hal/blob/gpiote/examples/gpiote-demo/src/main.rs

[jonas-schievink]

#167 was merged.