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Rust on TM4C129 Launchpad

Example programs for the TM4C129-XL Launchpad board, based on the stellaris-launchpad crate.

Requirements

  • rustc components (for cross-compiling and linking modifications)
  • arm-none-eabi-* (ARM Embedded Toolchain for compiler)
  • libusb-1.0-0-dev (for lm4tools)
  • lm4tools (serial interface to Launchpad bootloader)
  • TI drivers for the in-circuit debugger (to connect to the board's UART via USB)

The process described here works (with some offroading) on Linux and Mac, but has not been tested on Windows.

Setup

Rustc components

rustup component add rust-src
rustup target add thumbv7em-none-eabihf
cargo install flip-link

ARM Embedded Toolchain

Download from the ARM developer site and install. Unfortunately the install does not add the binaries to path.

Add the binaries to path however you like; on mac, you can add a line to your ~/.bash_profile

export PATH="$PATH:/Applications/ARM/bin/"

Flip-link

This crate is configured to use flip-link to prevent stack overflow from corrupting the program. See https://crates.io/crates/flip-link .

lm4tools

lm4tools provides a serial interface to the Stellaris bootloader on the launchpad board, in combination with the USB drivers from TI. Not all forks of lm4tools include unlocking capability, but the one recommended here does, and has worked consistently.

First, get libusb.

# Mac
brew install libusb
# Ubuntu (note the generic libusb-dev package is broken! must install specific version)
sudo apt install libusb-1.0-0-dev

Clone https://github.com/uastw-embsys/lm4tools (or one of the 40+ other forks of lm4tools) and run make to build the binaries. Then, similar to the ARM toolchain, you can add another line to your bash run command file to get the lm4flash binary into your path, or just reference its path manually with each use.

TI Drivers

Follow the instructions at https://software-dl.ti.com/ccs/esd/documents/ccs_downloads.html to install the latest version of the USB drivers.

Compile and flash

# Compile
cargo build --example blink --release

# Convert binary to a compatible format
arm-none-eabi-objcopy -O binary target/thumbv7em-none-eabihf/release/examples/blink target/thumbv7em-none-eabihf/release/examples/blink.bin

# Flash the board
sudo lm4flash target/thumbv7em-none-eabihf/release/examples/blink.bin

Serial comms

The on-board bootloader acts as a UART-to-USB bridge for UART0. This connection can be monitored using PuTTY on any platform. On Mac, you can also use screen (replacing the usb connection name) like:

# To exit, do
# CTRL-A
# CTRL-     (continue holding down CTRL!)
# CTRL-C
screen /dev/tty.something 115200

On Ubuntu,ls -l /dev/serial/by-id will show which device is associated with which port.

Figuring out which serial port it is can be tedious on a Mac. Just watch ls /dev/tty* while plugging/unplugging the board a few times.

Future Plans

  • Better network interface
  • DHCP-inform capability for static addressing on DHCP-managed networks
  • Hardware-in-the-loop testing using a self-hosted github-actions runner (probably a raspberry pi on a shelf) with an unlocking procedure to keep the board from being bricked during testing.