rp-hal VS tinyusb

probably, I didn't really check it, but I found [1]. Rust has a lot of support for embedded systems, even from the companies that provide the chips, like STM and Espressif.

[1] https://github.com/rp-rs/rp-hal

About the same time, I was learning Rust and discovered how it could be used on embedded targets from Low Level Learning on YouTube, the video introduced me to the amazing rp-hal crate that provides abstractions to talk to the Raspberry Pi Pico microcontroller. Getting used to the no_std mode took some time, the most challenging was not being able to collect an iterator to a container.

Well, just as I posted this, I came across the issue on Github: https://github.com/rp-rs/rp-hal/issues/525

Have a read of https://github.com/rp-rs/rp-hal/issues/257 for more info.

I've made an example for a RPI Pico (PR for the RP2040 HAL project here) .

Here's an example: https://github.com/rp-rs/rp-hal/blob/main/boards/rp-pico/examples/pico_usb_twitchy_mouse.rs

Embedded rust for the raspberry pi pico: https://github.com/rp-rs/rp-hal

What are you on about, can you clarify? Rust can compile in no-std/embedded style just as fine (or better) than C can for basically any ARM or RISCV based processor, and quick googling shows this hal for nearly all pi needs and even MEGA65 is "as supported" (read: not at all officially by anything, fan-only) as any current C compiler. Setting up rust for a new target, so long as the code-gen is supported somehow by LLVM, LLVM plugin, LLVM IR transpiler (and maybe libgcc-jit sort of soon) is just as painful or unpainful as setting up a whole team to work via C/C++ with comparable testing harnesses. This doesn't mean easy and is an area Rust is still improving rapidly by the various enterprise agencies (Ferrous systems, Oxide, more I can't remember...) who specifically want to bring rust to such low end hardware because frankly both C and C++ suck with vendor proprietary tool chains and quirks.

He says he can't find crate for 'bare_metal'. He was setting up and testing the HAL for the pico (https://github.com/rp-rs/rp-hal). While compiling it pulls down critical-section-0.2.7/src/lib.rs and bars on line 7

Implementing the required USB host interface is another hurdle, but tinyusb seems to have sorted most of that out, except that UAC2 is implemented as a device while you need a host.

Have a look at TinyUSB. It supports the STM32WB and demo programs for the Nucleo-WB55RG. It even offers an example for dual CDC ports, so very close to what you're looking for.

Second: Distrust, misunderstanding, and out of date opinions of C++ in embedded spaces. I often see "compatibilty" thrown around as a goal for using C and not C++, but for most modern embedded systems, C++ compilers exist and are (usually) well tuned. Arm is a shining example here*. C++ is more optimizable than C as the intent can be clearer to the compiler. C++ constexpr and templates are a godsend for embedded systems, and I used both heavily in my recent arduino and pico testing. I combined both of them for a really cool experimental USB interface descriptor builder that runs at compile time and avoids the need to count byte sizes, but I gave up on it when the maintainer said C only, despite the fact that C can't do that. I was similarly disappointed when the pico "C++" was C only, as there was no backwards compatibility necessary.

I looked at this but the fork seems to have had a lot of problems from looking at the PR: https://github.com/hathach/tinyusb/pull/1219

I think a better solution might be to use a USB flash drive in the usbc port. Unfortunately micropython and circuitpython don't support this (yet), so you'd have to use c++ https://github.com/hathach/tinyusb

It's possible to make the s3 be a mass storage device via TinyUSB. https://github.com/hathach/tinyusb/tree/master/examples/device/cdc_msc_freertos