Added the ability to use blocking Write implementation.

[esden]

It is useful to also be able to use the blocking::Write trait implementation. Some libraries like embassy-rs only implement the blocking version of the Write trait but not the non blocking one.

[gauteh]

Do you think it would be possible for us to create an DefmtSerialTarget trait, implement it for whatever interface, and then just take that at the in defmt_serial? Then there would be only one entry point for the user.

[gauteh]

Actually it seems that most implementations of non-blocking Write would also have a default blocking write: https://docs.rs/embedded-hal/latest/src/embedded_hal/blocking/serial.rs.html#23 (but it is not guaranteed?). Since we need blocking write in defmt we should maybe only support blocking::Write. The default implementation is essentially the same as what we are doing anyway.

[esden]

I was about to get back to you and say we can implement a trait to provide both interfaces. But I think you are right that just defaulting to blocking is the way to go as it is what we need anyways. I can make the necessary change if you are ok with that.

[esden]

I went ahead and pushed the "just blocking" version of the patch. I hope that is ok. I will check tomorrow in case you change your mind and want me to do something different. :)

[gauteh]

Yes. I think this is the way to go. The only issue is that HAL's have to opt-in to the default implementation, by doing something like:

impl blocking::serial::write::Default for MySerial {}

When they are not, it's probably a bug in the HAL anyway (I think I might have this bug in ambiq-hal), but I guess users could bug the HAL and stick to the old version of defmt-serial in the meantime.

[esden]

I think that makes sense. At least there is a fallback. That said, take your time, maybe ask what the ambiq-hal folks think before you merge this. No rush I just use my branch as a [patch] for my code in the mean time. :)

[gauteh]

I added a bunch of CI tests. I also added the blocking Write impl to ambiq-hal (https://github.com/gauteh/ambiq-rs/blob/main/ambiq-hal/src/uart.rs#L136), but there is something not linking as it should. Maybe some outdated dependencies. Maybe you will figure it out before me.

[esden]

On my end the system is complaining that the Cargo.toml is referring to ambiq-rs v0.2 not v0.3. Updating that dependency did the trick over here.

[gauteh]

I forced push a rebase with updated deps to your PR. I am guessing the example pi pico, or at least the example-std needs to be adapted to your changes, while I have fixed the artemis example (through the HAL).

example-std may just need:

[dependencies]
critical-section = { version = "1.1", features = ["std"]}

[esden]

Ok, I worked out the changes needed for the example-std to compile.

Beyond that, I need to add rust-toolchain.toml in the toplevel and example projects to make things compile here as the project requires nightly toolchain. I don't have that set globally on my system. It might be a good idea to carry the rust-toolchain.toml files. But maybe there is a reason you don't have them and I rather ask before I add them to this PR.

[gauteh]

Thanks, merged. The nightly requirement is not introduced by us, and rust-toochain wont have any effect on dependents of the lib. So we'll leave that to the users of the library. Making a new release.

[esden]

Ok, sounds good. Thank you very much for merging and releasing! :)