Zinc, the bare metal stack for rust

Maintenance update

Zinc isn't being actively developed or maintained and should be considered more of an academic experiment at this point. There's a whole rust embedded WG now and many projects used ideas featured in zinc to make embedded development with rust as easy as possible. I'd suggest looking at tock to start with.

About zinc.rs

Zinc is an experimental attempt to write an ARM stack that would be similar to CMSIS or mbed in capabilities but would show rust's best safety features applied to embedded development.

Zinc is mostly assembly-free and completely C-free at the moment. One of the goals of zinc is to figure out, how much of the usual RTOS stack is it possible to write in rust in a safe manner, while keeping the resource usage profile low enough (comparable to C/C++ code).

Useful links:

• blog
• build stats (output binary size change over time)
• api docs

Main features

Zinc provides you with safe code in terms of rust code safety; accessing hardware directly is unsafe, but you can do that as well if you want.

In addition to software safety, zinc provides hardware safety with Platform Tree specification; you define the hardware configuration right in the code in simple key-value DSL and compiler verifies that all hardware is configured properly; that also allows to optimize the code to much bigger extent than with conventional RTOSes.

There is also an effort to generate platform tree specifications for new platforms from ARM CMSIS SVDs such as those aggregated by the cmsis-svd project.

Supported hardware

Some level of support is currently provided for the following processor families. Not all peripherals are supported for all processors at this time.

• NXP lpc11xx
• NXP lpc17xx
• Freescale k20
• ST STM32f4
• ST STM32l1

In the future, a better story will be available that will allow for additional processor families, processors, and boards using those processors to be defined more easily.

License

Zinc is distributed under Apache-2.0, see LICENSE for more details.

Usage

Environment Setup

For the time being, Zinc makes use unstable features of the Rust language. As such, we recommend using the latest nightly version of Rust for development. As features of the language stabilize over time, it is the goal of Zinc to eventually be able to target stable versions of the compiler. rustup.rs may be used to manage installations of multiple versions of rust on single machine.

The currently supported Rust version is nightly-2016-09-17. To install it with rustup use the following:

rustup install nightly-2016-09-17
rustup override set nightly-2016-09-17

In addition to rust itself, a GCC cross-toolchain for ARM must be installed. Although LLVM is used for a majority of compilation, the GCC Linker is still used at this time. The GCCM ARM Embedded toolchain works well for most people.

Building Examples Within Zinc

There are several examples available within the Zinc source itself. Zinc makes use of Xargo (a bare metal variant of Cargo) for its build system, but it is still necessary to provide the build system with a few pieces of information for it to properly compile for your target.

Namely, xargo must know about and have access to:

1. The target specification for the machine being specified (consumed by the compiler)
2. A feature telling the code what platform is being targetted. These features are defined in the form mcu_<platform>.

Suppose we are targetting the k20 platform. In that case, I could build the blink_k20 example program by doing the following. Refer to build-jenkins.sh for a mapping of platforms to targets.

$ cd examples/blink_k20
$ ln -s ../../thumbv7em-none-eabi.json
$ xargo build --target=thumbv7em-none-eabi --features mcu_k20 --release

$ file target/thumbv7em-none-eabi/release/blink
target/thumbv7em-none-eabi/release/blink: ELF 32-bit LSB executable, ARM, EABI5 version 1 (SYSV), statically linked, not stripped

If you receive link errors, you probably need to tell Xargo to use your cross-compilers linker. You can do this by adding a .xargo/config to either your home directory or the root of the Zinc project:

[target.thumbv7em-none-eabi]
linker = "arm-none-eabi-gcc"
ar = "arm-none-eabi-ar"

Using Zinc for your Project

Since Zinc uses xargo for its build system, using Zinc from your own project just requires setting up your Cargo.toml correctly.

You can find an example of how to do that here: https://github.com/posborne/zinc-example-lpc1768

Contacting developers

You can find us at IRC: #zinc on irc.mozilla.org.