`Qei` API

[japaric]

trafficstars

• What is missing in this API?
• Can this API be implemented for different devices?

[japaric]

Update: this trait is available in release v0.1.0 behind the "unproven" Cargo feature.

[leshow]

I wrote a library for a simple rotary encoder library, and after posting about it in the rust-embedded/awesome-rust thread, someone directed me to this trait, that I had no idea existed.

I'm having trouble for seeing how to map to the methods provided in the trait. Particularly the direction method.

Direction in embedded-hal has 2 variants, and the direction() function returns Direction. However, in my case, it's possible there is no change in direction, and the Count type itself has no inherent direction. The only thing I can think of is returning Updirection if the count is above zero and Down in the other case, but that doesn't really provide anything useful for a rotary encoder

It's very possible I'm just not understanding something, but I can't see how it fits together at all.

In my case, something like this would make a lot more sense:

pub trait Qei {
type Count;
    fn count(&self) -> Self::Count;
    fn direction(&self) -> Option<Direction>;
}

or even,

fn direction(&mut self) -> Option<Direction>

In this case, I can put the code that does the transformation of state -> Direction (and updates the internal count) in the direction() function