Add embassy microcontroller example demonstrating async

[ninjasource]

An async demo using Embassy and an embedded stm32u5g9j-dk2 development kit. This demonstrates a method to use async in Slint with a microcontroller. The simulator can run on a PC if you do not have the dev kit on hand but it is not meant to be a reference design for an async GUI implementation on a PC.

[CLAassistant]

All committers have signed the CLA.

[ninjasource]

Hi, I have given this PR some thought and decided that adding the Slint copyright notice in the Cargo.toml file (or elsewhere) is problematic for my use case as I use this example as the basis of my commercial projects and it is not appropriate to have to include this notice in them. Transferring copyright means that I am exposing myself to risk in other projects as a result. Therefore I would like to retract my signing of the digital CLA contract yesterday and retract this pull request. I’m really sorry to have to do this and I understand the need for your project to have a CLA and copyright notices but it is just not compatible with my risk level. There are no easy answers here and I hope you understand. If Slint really wants an embassy example they are welcome to link to my repository. Also, the Embassy project is so fluid that referencing it from Slint via git revision numbers may be too weak for your stability goals at this time. Keep up the great work!

[tronical]

Hi David! I'm sorry to hear that, but I understand. Thanks for your clear communication. Yes, linking to your repository is a good idea. I'll take a look to see how we can retract the CLA signature.

[tronical]

Regarding, the signature, @ninjasource , I think that you can go to https://cla-assistant.io/my-cla and revoke it from there.

[tronical]

FWIW, I haven't looked at the diff yet - that was still on my TODO. I'll abstain from doing that, and I hope that perhaps we can implement an embassy example ourselves in the future.

[ninjasource]

Thanks for understanding and thanks for the link. I have a suggestion for demo projects like this that don’t include changes to the core codebase. Perhaps Slint can host a repository that simply links to various open source projects that use Slint.

Something like this as an example: https://github.com/rust-embedded/awesome-embedded-rust

That list is super easy to add to and fairly easy to do housekeeping on for the occasional repos that get taken offline. The Slint team won’t have the arduous task of keeping old demos alive and they will also get insights on how Slint is actually being used in the wild.

[ogoffart]

Thanks for submitting the PR.

Note that the CLA does not imply copyright transfer. It simply license your code to us under the MIT-0 license.

Now, the CI does indeed check that all files have a license and the test are a bit strict as it force a copyright to Slint which is not needed. So we'd need to fix our CI to allow 3rd party copyright holder. (Which we should have done before as this is not the first time the problem comes up)

I do think having an embassy example would be a great addition in the repository.
Would you be open to keep the PR if we fix our CI to accept less strict copyright lines?

[ninjasource]

Hi @ogoffart,

Yes I would be open to keeping the PR and I am glad that you think it will be a great addition to the Repository!

"Note that the CLA does not imply copyright transfer. It simply license your code to us under the MIT-0 license."

Great, that makes sense, I'm happy with that.

"So we'd need to fix our CI to allow 3rd party copyright holder."

That sounds like a good solution. I would even be open to removing copyright notices on example code but that is up to you guys. I was just uncomfortable with the possibility of losing access to something I had written and use in other projects.