n32g4xx-hal

This HAL is very unpolished and much of its functionality Does Not Work or may require hacks accessing the PAC.

APIs are subject to change quickly and rapidly.

HAL for the N32g4xx family of microcontrollers

Quick start guide

Embedded Rust development requires a bit more setup than ordinary development.

You will also need a debug probe, for example an ST-Link V2 for programming and debugging. (There are many different STLink probes out there, all of them should work fine with the instructions given here, other JTAG or SWD debug probes will work as well but will need different software or configuration).

Anecdotally, ST-Link V2 seems to be more reliable than other options.

Installing software

To program your microcontroller, you need to install:

• openocd or stlink
• gdb-multiarch (on some platforms you may need to use gdb-arm-none-eabi instead, make sure to update .cargo/config to reflect this change)

Finally, you need to install arm target support for the Rust compiler. To do so, run

rustup target install thumbv7em-none-eabihf

Setting up your project

Create a new Rust project as you usually do with cargo init. The hello world of embedded development is usually to blink an LED and code to do so is available in examples/blinky.rs. Copy that file to the main.rs of your project.

You also need to add some dependencies to your Cargo.toml:

[dependencies]
embedded-hal = "1.0.0"
nb = "1.1.0"
cortex-m = { version = "0.7.7", features = ["critical-section-single-core"] }
cortex-m-rt = "0.7.3"
# Panic behaviour, see https://crates.io/keywords/panic-impl for alternatives
panic-halt = "0.2.0"
n32g4xx-hal = { version = "0.1.0", features = ["rt", "gd32c103"] }

If you build your project now, you should get a single error: error: language item required, but not found: eh_personality. This unhelpful error message is fixed by compiling for the right target.

We also need to tell Rust how to link our executable, and how to lay out the result in memory. To accomplish all this, copy .cargo/config and memory.x from the n32g4xx-hal repo to your project.

cargo build

If everything went well, your project should have built without errors.

Programming the microcontroller

It is now time to actually run the code on the hardware. To do so plug your debug probe into your board and start openocd using

openocd -f interface/stlink-v3.cfg -f target/stm32f1x.cfg

If you are not using an stlink V3, change the interface accordingly. For more information, see the embeddonomicon.

If all went well, it should detect your microcontroller and say Info : stm32f1x.cpu: hardware has 6 breakpoints, 4 watchpoints. Keep it running in the background.

We will use gdb for uploading the compiled binary to the microcontroller and for debugging. Cargo will automatically start gdb thanks to the .cargo/config you added earlier. gdb also needs to be told to connect to openocd which is done by copying .gdbinit to the root of your project.

You may also need to tell gdb that it is safe to load .gdbinit from the working directory.

• Linux

  echo "set auto-load safe-path $(pwd)" >> ~/.gdbinit
  

• Windows

  echo set auto-load safe-path %CD% >> %USERPROFILE%\.gdbinit
  

If everything was successful, cargo should compile your project, start GDB, load your program and give you a prompt. If you type continue in the GDB prompt, your program should start and an LED attached to PC13 should start blinking.

Going further

From here on, you can start adding more code to your project to make it do something more interesting. For crate documentation, see docs.rs/n32g4xx-hal. There are also a lot more examples available. If something is unclear in the docs or examples, please, open an issue and we will try to improve it.

Selecting a microcontroller

This crate supports multiple microcontrollers in the n32g4xx family. Which specific microcontroller you want to build for has to be specified with a feature, for example gd32c103.

If no microcontroller is specified, the crate will not compile.

Supported Microcontrollers

• gd32c103xx (e.g. GD32C103TB, GD32C103CB, GD32C103RB, GD32C103VB)
• gd32c113xx (e.g. GD32C113TB, GD32C113CB, GD32C113RB, GD32C113VB)

Trying out the examples

You may need to give cargo permission to call gdb from the working directory.

• Linux

  echo "set auto-load safe-path $(pwd)" >> ~/.gdbinit
  

• Windows

  echo set auto-load safe-path %CD% >> %USERPROFILE%\.gdbinit
  

Compile, load, and launch the hardware debugger.

$ rustup target add thumbv7em-none-eabihf

# on another terminal
$ openocd -f interface/$INTERFACE.cfg -f target/stm32f1x.cfg

# flash and debug the "Hello, world" example. Change gd32c103 to match your hardware
$ cargo run --features gd32c103 --example hello

$INTERFACE should be set based on your debugging hardware. If you are using an stlink V2, use stlink-v2.cfg. For more information, see the embeddonomicon.

Using as a Dependency

When using this crate as a dependency in your project, the microcontroller can be specified as part of the Cargo.toml definition.

n32g4xx-hal = { version = "0.1.0", features = ["gd32c103", "rt"] }

Documentation

The documentation can be found at docs.rs.

License

Licensed under either of

• Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.

Contribution

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.

See the contributing guide for more details.