Adding Basic RTC API

[cesardtamayo]

Add Hardware Agnostic RTC API with unit testing.
The API is being used by examples/smt32wba6/src/bin/rtc.rs

Unit tests added:

• test_rtc_defaults_to_correct_date
• test_rtc_instantiates_correctly
• test_rtc_updates_date_time_correctly

[Dirbaio]

Unfortunately I don't think we should do this. It's not embassy-stm32's job to define traits for abstracting over different RTC hardware.

An RTC trait is something that could go in the embedded-hal crate, then embassy-stm32 could implement that.

[cesardtamayo]

Unfortunately I don't think we should do this. It's not embassy-stm32's job to define traits for abstracting over different RTC hardware.

An RTC trait is something that could go in the embedded-hal crate, then embassy-stm32 could implement that.

Do you mean the embassy-hal-internal directory? I could implement it the way you are suggesting

[Dirbaio]

No, embedded-hal

[Dirbaio]

I meant rust-embedded/embedded-hal, that's where the link in my previous comment goes. This is maintained by the Rust Embedded Working Group, not Embassy.

In general the Embassy project doesn't define traits for abstracting things because they're an "ecosystem-wide" concern. If Embassy defines its own trait and implements it on its HALs, it's not very useful because you still can use it with Embassy only, other non-Embassy HALs won't implement it.

If the trait is in embedded-hal, which is from the Rust Embedded WG, a wider part of the ecosystem tends to implement it, which makes it more useful.

I'm not sure how easy it'll be to add an RTC trait to embedded-hal though. The datetime from embassy-stm32 is stm32-specific, other RTCs probably do it differently or are missing features (like day of week, or microseconds)

[cesardtamayo]

I meant rust-embedded/embedded-hal, that's where the link in my previous comment goes. This is maintained by the Rust Embedded Working Group, not Embassy.

In general the Embassy project doesn't define traits for abstracting things because they're an "ecosystem-wide" concern. If Embassy defines its own trait and implements it on its HALs, it's not very useful because you still can use it with Embassy only, other non-Embassy HALs won't implement it.

If the trait is in embedded-hal, which is from the Rust Embedded WG, a wider part of the ecosystem tends to implement it, which makes it more useful.

I'm not sure how easy it'll be to add an RTC trait to embedded-hal though. The datetime from embassy-stm32 is stm32-specific, other RTCs probably do it differently or are missing features (like day of week, or microseconds)

I'll talk to the team to see if that's worth pursuing. We are trying to add some APIs that we could use in the future, but what you are saying makes sense to me.
Thank you for the feedback :)