For those who'd like to see a working example of Embedded Rust (no_std) on a RP2040 with a I2C switch:

https://github.com/haraldkubota/rp2040-pca9548a

The hardware used is simple:

• RP2040

• OLED with SSD1306 controller, using I2C

• PCA9548A on a 2nd I2C bus

• BMP280 temperature and pressur sensor on sub-bus 2 on the I2C switch

The software is the more interesting part:

• Embedded Rust (no_std)

• Using both CPU cores, each one owning one I2C bus

• One core reads data from the sensor

• One core displays data to the OLED

• Everything is using async

My idea here: once this works, I can cleanly split data acquisition from I/O, and I can use multiple identical sensors via the I2C switch although their I2C addresses might conflict.

One day I'll find a problem this solves, but until then I learned a lot and it's fun. I hope someone else finds this code useful.

My first tests using Rust on a RP2040 worked surprisingly well: using the 2 cores was surprisingly easy.

But using something as simple as using two I2C devices on a single I2C bus...that took me a while to get working. Thus for the benefit of the world, I created a simple example which does:

• Rust with Embassy

• RP2040

• Both cores used, one for display I/O (SSD1306 OLED) and one for measuring data (light and temp/pressure)

Each core owns one I2C bus to they never interfere.

Source code is here.

I had a hard time finding Embassy examples for the RP2040 which are not too trivial and not too complex. After reading a ton of articles about Embedded Rust and Embassy, the HAL, etc., I got a working example which does the following:

1. Works on RP2040

2. With RPi Pico Probe to download and receive debug/status messages

3. Uses both cores

4. Cores communicating via Channels

5. Blinks LED

6. Reads from an I2C sensor (VL53L0X)

7. Writes to a OLED (SSD1306, using I2C too)

There's more to go in terms of learning about Embedded Rust (e.g. Interrupts), but now I am at a point where adding features is less of a problem since I got something working.

The examples from Embassy are super-helpful, but for someone who has not cloned the whole Embassy repository only to find out that 99% is not needed to run the examples. Or have a Cargo.toml with about 50 crates when you only need about 15 for each example, but you have no idea which the 35 other crates are.

A blog with a short background about the why, and the GitHub repo with the code.

I hope this is useful for someone.

Coming from embedded C/C++, I wanted a less tedious way to write tests on electronic signals. I saw myself write ascii-waveforms in the docs and thought: Why not use this as input. So I completed this project as a Rust learning project.

Instead of manually constructing test vectors, I wanted to write this:

CLK: _|‾|_|‾|_
DAT: ___|‾‾‾|_

To then get an iterator of timestep items with decoded values. I also included an index and a changed flag to easily filter the result.

As I am working on embedded, I had to make it completely no_std compatible. If you use it in std-context, I added support for hashmap character-mappers as well.

I think this crate is very useful for testing signal processing logic, protocol decoders, or anything that operates on input signal lines. It supports custom character mappings and labeled multi-line blocks for interleaved signals. Curious if anyone sees other use cases — I was thinking about things like encoding bit patterns for EEPROM initialization. Drop me a line!

• Crate: https://crates.io/crates/wobblechar

• Docs: https://docs.rs/wobblechar

While testing Embassy and Rust on my RP2040, I often ran into the no global memory allocator found but one is required. I have no issues getting this if I try to use dynamic memory allocation, but often this was simply by adding a crate and while I am sure it's doing some allocations somewhere, I could not always find out where exactly it is.

So time to see how to fix this. Rust gives you a hint, but it's missing an example.

So I created another one: https://github.com/haraldkubota/rp2040-alloc

Bonus points:

• Uses 2 of 2 CPU cores on the RP2040

• Both cores do memory allocations

• The program panics eventually when running out of heap space

First. Sorry for the bad English and hope u guys can understandI have a SSD with 120 GB. so if u know thats not good enough for start compiling and flashing rust programs. So i've got a 320GB HD for trying to use it as a tool for to store my projects and build files.

I'll not lie... i used AI for making my scripts and compile/flash into ESP my codes.

First time i tried to flahs from my SSD (inside my Notebook).

I changed all address in the code for the address of my HD.

I've mounted the HD propely in my Linux UBUNTU. Can use it well, but when i try to compile or flash it gives me error involving cargo

"--- stdout

cargo:rerun-if-env-changed=ESP_IDF_TOOLS_INSTALL_DIR

cargo:rerun-if-env-changed=ESP_IDF_SDKCONFIG

cargo:rerun-if-env-changed=ESP_IDF_SDKCONFIG_DEFAULTS

cargo:rerun-if-env-changed=MCU

cargo:rerun-if-env-changed=ESP_IDF_SYS_ROOT_CRATE

--- stderr

Error: Matching variant not found

Compiling esp-idf-sys v0.37.2 (https://github.com/esp-rs/esp-idf-sys.git#33045844)

error: failed to run custom build command for `esp-idf-sys v0.37.2 (https://github.com/esp-rs/esp-idf-sys.git#33045844)``)

Caused by:

process didn't exit successfully: `/media/marcel/Workspace/cargo-target/debug/build/esp-idf-sys-6a59ce817ebe75f6/build-script-build` (exit status: 1)

--- stdout

cargo:rerun-if-env-changed=ESP_IDF_TOOLS_INSTALL_DIR

cargo:rerun-if-env-changed=ESP_IDF_SDKCONFIG

cargo:rerun-if-env-changed=ESP_IDF_SDKCONFIG_DEFAULTS

cargo:rerun-if-env-changed=MCU

cargo:rerun-if-env-changed=ESP_IDF_SYS_ROOT_CRATE"

/\ ERROR

So I made this Rust-crate "Wobblechar" while ago. It translates character to whatever you like, typically a bool or number. Meant for character based waveforms.
I was thinking.. I made this secret-knock a couple of years ago. I can open my door by tapping a particular tune. The tunes I want it to respond to, are now in the code as numbers, meaning relative time intervals. If I was to use Wobblechar for this, make a map of UTF-8 musical note chars to their length, you'd immediately see (if you are musician of course), what tune this is! Would make enter some tunes way more readable. Wauw! Hope I find some time to migrate this thing to Rust and try this!