Rust Baremetal on Teensy 4.0

This project provides Rust abstractions for the NXP i.MX RT1062 processor used in the Teensy 4.0. It is intended to be usable as a library, although currently only works for executables defined in its own examples directory.

It is very early in development, and as such as more limitations than feature.

Limitations

• Code runs only off of flash (as does .rodata)
• No .data section, since we cannot copy the initialization data in yet
• Cannot be used as a dependency crate

Capabilities

Currently, this crate can bring up the microcontroller sufficiently to send messages over a UART.

Dependencies

In order to build and use this project, you'll need the following:

• A recent Nightly build of Rust, installed using rustup
• An Arduino environment with Teensyduino installed on top of it
• GNU Make (BSD Make variants may work, but are untested)

Running Examples

To run the examples, set an ARDUINO environment variable that points to your teensyduino installation, then run make <examplename>. This will build the requested example and open the Teensy loader to flash it. You can then simply hit the reset button on your Teensy, just as you would in the Arduino environment.

$ export ARDUINO=$HOME/Downloads/arduino-1.8.9 # Or wherever your Arduino lives
$ make bootup

Next Steps

In no particular order, the following hardware bits need abstractions built for them. These will likely be similar to what I did for Teensy 3.2, where it makes sense.

• GPIO
• CCM
• SPI
• USB (especially USB serial for debugging)
• DMA

There are also some remaining memory management bits that need doing:

• ITCM and DTCM setup
• Copying code/data into correct memories
• A heap

Lastly, a Cargo build.rs script needs to be written so that we force the appropriate linker script when this crate is consumed. This will allow its use as a library.