imxrt-hal

A Rust hardware abstraction layer (HAL) for NXP i.MX RT processors.

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Goals

• Create the collaborative group to support using Rust on NXP's i.MX RT series.
• Simple but useful register level access. It compiles quickly, and it's intuitive for existing embedded developers. Every hal republishes the RAL.
• Embedded HAL support.
• RTIC support.
• NXP EVK board support
• Supporting popular boards such as the Teensy 4.

Getting Started

HAL

If you want to develop Rust libraries and applications for an i.MX RT-based system, use the imxrt-hal crate. The imxrt-hal crate provides implementations of the embedded-hal traits specific to i.MX RT processors. Use the HAL if you want to

• toggle GPIOs
• use timers (GPTs, PITs)
• control PWM outputs (single pin)
• talk to I2C devices
• read and write serial data (UART)
• send and receive data over SPI

The publicly-supported HAL is on crates.io. Include the HAL in your Rust library or binary:

[dependencies.imxrt-hal]
version = "0.4"
features = ["imxrt1062", "rt"] # "rt" flag optional

Note the "imxrt1062" feature flag. You're required to supply a feature flag that describes your i.MX RT variant. The HAL supports the following processors, as identified by feature flags:

• "imxrt1062"

The "rt" feature flag is recommended for users who are

• building executables that run on i.MX RT processors
• creating board support packages (BSP), or higher-level libraries, for i.MX RT systems

Enabling the "rt" feature-flag will link in the i.MX RT interrupt table. If you're familiar with crates that are generated from svd2rust, the "rt" feature has the same behaviors in the imxrt-hal as it does in svd2rust-generated crates.

Future of the HAL

Follow #56 to understand how we're breaking imxrt-hal into separate crates. If you'd like to try the new HAL crate(s), depend on imxrt1060-hal, and skip the feature flag that describes your i.MX RT variant.

Q/A

Are there any board support packages (BSP) that use the imxrt-hal crate?

There are a few BSPs that use the imxrt-hal crate:

• The imxrt1060evk-bsp crate, useful for the i.MX RT 1060 Evaluation Kit (EVK).
• The teensy4-bsp crate, supporting Rust development on the Teensy 4.

Consider using those crates if you already own those hardware platforms, as they may provide a simpler foundation for building Rust applications.

How can I use Rust to boot an i.MX RT-based system? Does the HAL provide the reset handler?

Neither the HAL nor the RAL can help you boot an i.MX RT-based system. Typically, Rust developers use the cortex-m-rt crate as a minimal runtime for Cortex-M processors. However, i.MX RT processors require more setup than what the cortex-m-rt crate offers. As of now, you're required to use your own runtime crate to support i.MX RT processor start-up.

We have some components that might be helpful when building your own runtime crate:

• The imxrt-boot-gen crate lets you define some of the data structures that are required to boot i.MX RT processors. It's used in the other projects listed below.
• The imxrt-rt crate provides a runtime crate that may be useful for other i.MX RT processors. It's the runtime crate used in the imxrt1060evk-bsp crate.
• The teensy4-rs project provides its own runtime crate that utilizes the tightly-coupled memory (TCM) regions. The runtime is specific for the Teensy 4, although it may be used elsewhere.

Why not use svd2rust to generate a crate for register access?

See here and here. svd2rust generates a crate that's nearly 1 million lines of Rust code, and it takes a few minutes to compile. On the other hand, the RAL compiles in a few seconds. Additionally, svd2rust only supports one SVD input, but the RAL auto-generation script accepts multiple SVD inputs, sharing the common peripherals across processor families. This means that we can more easily support all i.MX RT processor variants from a single crate.

Contributing & Development

For contributions and development guidance, see CONTRIBUTING.md

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.