[Solved] Cannot find `pwm` in `embedded_hal`

[Sciancisco]

I have a problem importing SetDutyCycle.

Here are my imports:

use arduino_hal::prelude::*;
use arduino_hal::simple_pwm::*;
use embedded_hal::pwm::SetDutyCycle;
use embedded_hal::serial::{Read, Write};

Here is my error:

error[E0432]: unresolved import `embedded_hal::pwm`
 --> src/main.rs:9:19
  |
9 | use embedded_hal::pwm::SetDutyCycle;
  |                   ^^^ could not find `pwm` in `embedded_hal`

I built the documentation and I can find embedded_hal::pwm. I looked at the source of embedded_hal linked in the doc and it does declare pub mod pwm. embedded_hal is in the dependencies of my Cargo.toml. Therefore, rustc should find the pwm module.

But it gets weirder (to me at least) because looking at this same source code, it shouldn't be able to find the serial module because it is not declared in embedded_hal. In fact, search through all the doc, there is no module serial at all !..

I've managed to trace back the Read and Write traits to arduino_hal::prelude::{_embedded_hal_serial_Read, _embedded_hal_serial_Write}, but their source code link is broken as it tries to get embedded_hal/serial.rs.html, the non existent embedded_hal::serial...

And what's with embedded_hal and embedded_hal_v0? Because in avr_hal_generic it imports the Read and Write traits from v0 but v0 doesn't appear to exist anyway, not even in the Cargo.lock...

I am stumped that it finds a module that it shouldn't and cannot find a module that it should :laughing: :thinking:

[Rahix]

You are probably confused because we interface with two versions of embedded-hal:

• embedded_hal is the new v1.0 version that was released a few months back
• embedded_hal_v0 is the older v0.# version that was used by everyone before that. we still support it because there are many drivers that still target the older version only.

The relevant dependency definitions are here:

https://github.com/Rahix/avr-hal/blob/38549cc4142881d302374535b3621578ffccaff2/avr-hal-generic/Cargo.toml#L26-L33

You probably need to import the older version of embedded-hal to access the traits that you need.

[Sciancisco]

It worked! Thank you! I didn't know this cargo trick.

And thank you a lot for this library! First timer in embedded and with its documentation and examples, it is relatively easy to use.