stm32f4xx-hal VS meta-raspberrypi

I would personally use the abstractions provided by the stm32f4xx-hal crate more. See https://github.com/stm32-rs/stm32f4xx-hal/tree/master/examples/ for examples.

For this project, the audio ended up being the biggest challenge. I spent a few days on-and-off working on it because it would stop working as I modified the PWM frequency. I was eventually able to track it down to a bug in the HAL and opened a PR accordingly: https://github.com/stm32-rs/stm32f4xx-hal/pull/555

For my specific issue, I'm using the stm32f4xx-hal library to control a bunch of RGB leds, each with a pwm output. Since I have to get pins and timers where I can find them, each component of the led is made by something like

At the time of writing this post, I noticed that if going with option 1 stated earlier that returns a PWMChannel can prove to be quite problematic. In navigating the documentation, the PWMChannel implementations do not include methods that allow to get and set the period of the peripheral. There is an issue that I submitted here for that.

Maybe check out this example from the stm324xx-hal repo?

Here is an example for stm32f407 (trivial to change to stm32f411) that gets random numbers from the rng peripheral and displays them on an ssd1306 display: https://github.com/stm32-rs/stm32f4xx-hal/blob/master/examples/rng-display.rs although this uses Rust, which you may or may not like. Arduino will have you covered as well, obviously.

A major benefit of Rust in embedded is how easy it is to use libraries. This example implements USB serial communication on an STM32 in under 80 lines. You add some libs and if it compiles it works.

How do you figure Pis have bad integration with Yocto?

https://github.com/agherzan/meta-raspberrypi

For what it's worth, the entire Pi lineup is also well supported by Buildroot. In-tree, no less.

Embedded linux exactly. Major OEMs are using yocto. Check https://www.yoctoproject.org/

Been there. You don't want alpine or debian. Good gpos, but what you want is Yocto, which will let you build exactly and only what you need piece by piece including only the kernel modules for your hardware, the exact applications you use and no extras, and with a little extra tweaking, you can wire in Mender for ota updates and the ability to push custom images to clients that need specialization, or even fully unlocked images for customers that need it, plus if you're using an SD card, you can send users recovery drives instead of shipping full devices or let them build their own images without your proprietary code

I second Yocto. It's the kernel in use by the OpenBMC project

One last "option" is yocto but tis is not good for desktop, but it can be a fun project.