rp-hal

Rust support for the "Raspberry Silicon" family of microcontrollers
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Table of Contents

1. Getting Started
2. Programming
3. Roadmap
4. Contributing
5. License
6. Contact
7. Acknowledgements

Getting Started

So, you want to program your new Raspberry Silicon microcontroller, using the Rust programming language. You've come to the right place!

This repository is rp-hal - a collection of high-level drivers for the Raspberry Silicon RP2040 microcontroller and various associated boards, like the Raspberry Pi Pico and the Adafruit Feather RP2040.

If you want to write an application for Raspberry Silicon, check out our RP2040 Project Template.

If you want to write code that uses the Raspberry Silicon PIO State Machines, check out pio-rs. You can even compile PIO programs at run-time, on the RP2040 itself!

If you want to try out some examples on one of our supported boards, check out the list of Board Support Packages below, and click through to see the various examples for each board.

Before trying any of the examples, please ensure you have the latest stable version of Rust installed, along with the right target support:

rustup self update
rustup update stable
rustup target add thumbv6m-none-eabi

You may also want to install these helpful tools:

# Useful to creating UF2 images for the RP2040 USB Bootloader
cargo install elf2uf2-rs
# Useful for flashing over the SWD pins using a supported JTAG probe
cargo install --git https://github.com/rp-rs/probe-run.git --branch rp2040-support 

Packages

This git repository is organised as a Cargo Workspace.

There is a Hardware Abstraction Layer (or HAL) crate for the RP2040 chip, and Board Support Package crates for a number of RP2040 based PCBs. If you are writing code that should run on any microcontroller, consider using the generic Rust Embedded Working Group's Embedded HAL.

If you are writing code that should work on any RP2040 device, use the HAL crate. If you are running code on a specific board, use the appropriate BSP crate (which will include the HAL crate for you). Please note, you cannot depend on multiple BSP crates; you have to pick one, or use Cargo Features to select one at build time.

Each BSP includes some examples to show off the features of that particular board.

rp2040-hal - The HAL for the Raspberry Silicon RP2040

You should include this crate in your project if you want to write a driver or library that runs on the Raspberry Silicon RP2040, or if you are writing a Board Support Package (see later on).

The crate provides high-level drivers for the RP2040's internal peripherals, such as the SPI Controller and the I²C Controller. It doesn't know anything about how your particular board is wired up (such as what each IO pin of the RP2040 is connected to).

There are examples in this crate to show how to use various peripherals (GPIO, I²C, SPI, UART, etc) but note that the pin-outs may not match any particular board.

pico - Board Support for the Raspberry Pi Pico

You should include this crate if you are writing code that you want to run on a Raspberry Pi Pico - the original launch PCB for the RP2040 chip.

This crate includes the rp2040-hal, but also configures each pin of the RP2040 chip according to how it is connected up on the Pico.

adafruit_macropad - Board Support for the Adafruit Macropad

You should include this crate if you are writing code that you want to run on an Adafruit Macropad - a 3x4 keyboard and OLED combo board from Adafruit.

This crate includes the rp2040-hal, but also configures each pin of the RP2040 chip according to how it is connected up on the Macropad.

feather_rp2040 - Board Support for the Adafruit Feather RP2040

You should include this crate if you are writing code that you want to run on an Adafruit Feather RP2040 - a Feather form-factor RP2040 board from Adafruit.

This crate includes the rp2040-hal, but also configures each pin of the RP2040 chip according to how it is connected up on the Feather RP2040.

pico_explorer - Board Support for the Pimoroni Pico Explorer

You should include this crate if you are writing code that you want to run on a Pimoroni Pico Explorer - a board featuring a small LCD screen, a breadboard and some breakout headers.

This crate includes the rp2040-hal, but also configures each pin of the RP2040 chip according to how it is connected up on the Pico Explorer.

pico_lipo_16mb - Board Support for the Pimoroni Pico Lipo 16MB

You should include this crate if you are writing code that you want to run on a Pimoroni Pico Lipo 16MB - a board with USB-C, STEMMA QT/Qwiic connectors, plus a Li-Po battery charging circuit.

This crate includes the rp2040-hal, but also configures each pin of the RP2040 chip according to how it is connected up on the Pico Lipo.

Note that if you use this crate the compiler will expect the full 16MB flash space, and so it may not work if you only have the 4MB variant.

pro_micro_rp2040 - Board Support for the Sparkfun Pro Micro RP2040

You should include this crate if you are writing code that you want to run on a Sparkfun Pro Micro RP2040 - a smaller RP2040 board with USB-C and a WS2812B addressable LED.

This crate includes the rp2040-hal, but also configures each pin of the RP2040 chip according to how it is connected up on the Pro Micro RP2040.

qt_py_rp2040 - Board Support for the Adafruit QT Py RP2040

You should include this crate if you are writing code that you want to run on an Adafruit QT Py RP2040 - an extremely small form-factor RP2040 board from Adafruit.

This crate includes the rp2040-hal, but also configures each pin of the RP2040 chip according to how it is connected up on the Feather RP2040.

Programming

Rust generates standard Arm ELF files, which you can load onto your Raspberry Pi Silicon device with your favourite Arm flashing/debugging tool. In addition, the RP2040 contains a ROM bootloader which appears as a Mass Storage Device over USB that accepts UF2 format images. You can use the elf2uf2-rs package to convert the Arm ELF file to a UF2 format image.

For boards with USB Device support like the Raspberry Pi Pico, we recommend you use the UF2 process.

The RP2040 contains two Cortex-M0+ processors, which execute Thumb-2 encoded ARMv6-M instructions. There are no operating-specific features in the binaries produced - they are for 'bare-metal' systems. For compatibilty with other Arm code (e.g. as produced by GCC), Rust uses the Arm Embedded-Application Binary Interface standard or EABI. Therefore, any Rust code for the RP2040 should be compiled with the target thumbv6m-none-eabi.

More details can be found in the Project Template.

Loading a UF2 over USB

Step 1 - Install elf2uf2-rs:

$ cargo install elf2uf2-rs

Step 2 - Make sure your .cargo/config contains the following (it should by default if you are working in this repository):

[target.thumbv6m-none-eabi]
runner = "elf2uf2-rs -d"

The thumbv6m-none-eabi target may be replaced by the all-Arm wildcard 'cfg(all(target_arch = "arm", target_os = "none"))'.

Step 3 - Boot your RP2040 into "USB Bootloader mode", typically by rebooting whilst holding some kind of "Boot Select" button. On Linux, you will also need to 'mount' the device, like you would a USB Thumb Drive.

Step 4 - Use cargo run, which will compile the code and started the specified 'runner'. As the 'runner' is the elf2uf2-rs tool, it will build a UF2 file and copy it to your RP2040.

$ cargo run --release --example pico_pwm_blink

Loading with probe-run

The Knurling project has a tool called probe-run. This is a command-line tool which can flash a wide variety of microcontrollers using a wide variety of debug/JTAG probes. It is based on a library called probe-rs. Unlike using, say, OpenOCD, probe-rs can autodetect your debug probe, which can make it easier to use.

Currently, probe-rs supports the slightly unusual debug hardware in the RP2040, but the last released probe-run tool (v0.2.6, as of September 2021), does not. However, there is a special version of probe-run for the RP2040 called probe-run-rp.

Step 1 - Install probe-run-rp:

$ cargo install --git https://github.com/rp-rs/probe-run.git --branch rp2040-support 

Step 2 - Make sure your .cargo/config contains the following:

[target.thumbv6m-none-eabi]
runner = "probe-run-rp --chip RP2040"

Step 3 - Connect your USB JTAG/debug probe (such as a Raspberry Pi Pico running this firmware) to the SWD programming pins on your RP2040 board. Check the probe has been found by running:

$ probe-run-rp --chip RP2040 --list-probes
The following devices were found:
[0]: J-Link (J-Link) (VID: 1366, PID: 0101, Serial: 000099999999, JLink)

There is a SEGGER J-Link connected in the example above - the mesage you see will reflect the probe you have connected.

Step 4 - Use cargo run, which will compile the code and start the specified 'runner'. As the 'runner' is the probe-run-rp tool, it will connect to the RP2040 via the first probe it finds, and install your firmware into the Flash connected to the RP2040.

$ cargo run --release --example pico_pwm_blink

Loading with picotool

As ELF files produced by compiling Rust code are completely compatible with ELF files produced by compiling C or C++ code, you can also use the Raspberry Pi tool picoprobe. The only thing to be aware of is that picotool expects your ELF files to have a .elf extension, and by default Rust does not give the ELF files any extension. You can fix this by simply renaming the file.

Also of note is that the special pico-sdk macros which hide information in the ELF file in a way that picotool info can read it out, are not supported in Rust. An alternative is TBC.

Roadmap

NOTE These packages are under active development. As such, it is likely to remain volatile until a 1.0.0 release.

See the open issues for a list of proposed features (and known issues).

Contributing

Contributions are what make the open source community such an amazing place to be learn, inspire, and create. Any contributions you make are greatly appreciated.

The steps are:

1. Fork the Project by clicking the 'Fork' button at the top of the page.
2. Create your Feature Branch (git checkout -b feature/AmazingFeature)
3. Make some changes to the code or documentation.
4. Commit your Changes (git commit -m 'Add some AmazingFeature')
5. Push to the Feature Branch (git push origin feature/AmazingFeature)
6. Create a New Pull Request
7. An admin will review the Pull Request and discuss any changes that may be required.
8. Once everyone is happy, the Pull Request can be merged by an admin, and your work is part of our project!

Code of Conduct

Contribution to this crate is organized under the terms of the Rust Code of Conduct, and the maintainer of this crate, the rp-rs team, promises to intervene to uphold that code of conduct.

License

The contents of this repository are dual-licensed under the MIT OR Apache 2.0 License. That means you can chose either the MIT licence or the Apache-2.0 licence when you re-use this code. See MIT or APACHE2.0 for more information on each specific licence.

Any submissions to this project (e.g. as Pull Requests) must be made available under these terms.

Contact

Raise an issue: https://github.com/rp-rs/rp-hal/issues Chat to us on Matrix: #rp-rs:matrix.org

Acknowledgements

• Othneil Drew's README template
• Rust Embedded Working Group
• Raspberry Pi and the Pico SDK