led_client/rp-hal/README.md

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   <h3 align="center">rp-hal</h3>

  <p align="center">
    Rust support for the "Raspberry Silicon" family of microcontrollers
    <br />
    <a href="https://docs.rs/rp2040-hal"><strong>Explore the API docs »</strong></a>
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    <br />
    <a href="https://github.com/rp-rs/rp-hal-boards/tree/main/boards/rp-pico/examples">View Demos</a>
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<!-- TABLE OF CONTENTS -->
<details open="open">
  <summary><h2 style="display: inline-block">Table of Contents</h2></summary>
  <ol>
    <li><a href="#getting-started">Getting Started</a></li>
    <li><a href="#programming">Programming</a></li>
    <li><a href="#roadmap">Roadmap</a></li>
    <li><a href="#contributing">Contributing</a></li>
    <li><a href="#license">License</a></li>
    <li><a href="#contact">Contact</a></li>
    <li><a href="#acknowledgements">Acknowledgements</a></li>
  </ol>
</details>

<!-- GETTING STARTED -->

## 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](https://github.com/rp-rs/rp2040-project-template).

If you want to write code that uses the Raspberry Silicon PIO State Machines,
check out [pio-rs](https://github.com/rp-rs/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*][BSPs], 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:

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

You may also want to install these helpful tools:

```sh
# Useful to creating UF2 images for the RP2040 USB Bootloader
cargo install elf2uf2-rs --locked
# Useful for flashing over the SWD pins using a supported JTAG probe
cargo install --locked probe-rs-tools
```

## Packages

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.

[Cargo Workspace]: https://doc.rust-lang.org/cargo/reference/workspaces.html
[Embedded HAL]: https://github.com/rust-embedded/embedded-hal
[Cargo Features]: https://doc.rust-lang.org/cargo/reference/features.html

### [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.

### [BSPs] - Board support packages

There are BSPs for various boards based on the RP2040 available in
a [separate repository][BSPs].

[rp2040-hal]: https://github.com/rp-rs/rp-hal/tree/main/rp2040-hal
[Raspberry Silicon RP2040]: https://www.raspberrypi.org/products/rp2040/
[BSPs]: https://github.com/rp-rs/rp-hal-boards/

<!-- PROGRAMMING -->
## 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 compatibility 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].

### Linker flags

Besides the correct target, which mainly defines the instruction set,
it's also necessary to use a certain memory layout compatible with
the rp2040. To achieve that, rustc must be called with appropriate
linker flags. In the [Project Template], those flags are defined in
[`.cargo/config.toml`](https://github.com/rp-rs/rp2040-project-template/blob/main/.cargo/config.toml).
Another necessary file is
[`memory.x`](https://github.com/rp-rs/rp2040-project-template/blob/main/memory.x).

More detailed information on how the linker flags work can be found in
[the cortex_m_rt docs](https://docs.rs/cortex-m-rt/latest/cortex_m_rt/).

In most cases, it should be sufficient to use the example files from the
[Project Template].

### Loading a UF2 over USB

*Step 1* - Install [`elf2uf2-rs`](https://github.com/JoNil/elf2uf2-rs):

```console
$ cargo install elf2uf2-rs --locked
```

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

```toml
[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.

```console
$ cargo run --release --features "critical-section-impl,rt,defmt" --example pwm_blink
```

(The `pwm_blink` example doesn't need all these feature flags. They are listed here
so you can use the same command for all examples.)

### Loading with probe-rs
[probe-rs](https://github.com/probe-rs/probe-rs) is a library and a
command-line tool which can flash a wide variety of microcontrollers
using a wide variety of debug/JTAG probes. Unlike using, say, OpenOCD,
probe-rs can autodetect your debug probe, which can make it easier to use.

*Step 1* - Install `probe-rs`:

```console
$ cargo install --locked probe-rs-tools
```

Alternatively, follow the installation instructions on https://probe.rs/.

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

```toml
[target.thumbv6m-none-eabi]
runner = "probe-rs run --chip RP2040"
```

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

```console
$ probe-rs list
The following debug probes 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 message 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-rs` tool, it will connect to the
RP2040 via the first probe it finds, and install your firmware into the Flash
connected to the RP2040.

```console
$ cargo run --release --example 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 [picotool](https://github.com/raspberrypi/picotool). 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](https://github.com/raspberrypi/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.

[Project Template]: https://github.com/rp-rs/rp2040-project-template

<!-- ROADMAP -->
## 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](https://github.com/rp-rs/rp-hal/issues) for a list of
proposed features (and known issues).

<!-- CONTRIBUTING -->
## 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](https://github.com/rp-rs/rp-hal/pulls)
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 -->
## Code of Conduct

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

[CoC]: CODE_OF_CONDUCT.md
[rp-rs team]: https://github.com/orgs/rp-rs/people

<!-- LICENSE -->
## License

The contents of this repository are dual-licensed under the _MIT OR Apache 2.0_
License. That means you can choose either the MIT license or the Apache 2.0
license when you re-use this code. See [`LICENSE-MIT`](./LICENSE-MIT) or
[`LICENSE-APACHE`](./LICENSE-APACHE) for more information on each specific
license. Our Apache 2.0 notices can be found in [`NOTICE`](./NOTICE).

Unless you explicitly state otherwise, any contribution intentionally submitted
for inclusion in the work by you, as defined in the Apache-2.0 license, shall be
dual licensed as above, without any additional terms or conditions.

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## Contact

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

<!-- ACKNOWLEDGEMENTS -->
## Acknowledgements

* [Othneil Drew's README template](https://github.com/othneildrew)
* [Rust Embedded Working Group](https://github.com/rust-embedded)
* [Raspberry Pi](https://raspberrypi.org) and the [Pico SDK](https://github.com/raspberrypi/pico-sdk)