cookie-monster-rs

Embedded Rust project to drive a LED strip with a micro:bit v2

Prerequisites

cargo-binutils

$ rustup component add llvm-tools-preview

$ cargo install cargo-binutils

$ cargo size --version
cargo-size 0.3.6

cargo-embed

On Debian and derived distros, the following packages need to be installed:

$ sudo apt install -y pkg-config libudev-dev

Then install it with cargo:

$ cargo install cargo-embed

$ cargo embed --version
cargo-embed 0.18.0
git commit: crates.io

Rust Toolchain Target

$ rustup target add thumbv7em-none-eabihf

gdb

On Debian and derived distros, the following package need to be installed:

$ sudo apt-get install gdb-multiarch

NOTE gdb-multiarch is the GDB command you'll use to debug

minicom

On Debian and derived distros, the following package need to be installed:

$ sudo apt-get install minicom

udev Rules

Create the file /etc/udev/rules.d/99-microbit.rules and add the following content to it:

# CMSIS-DAP for microbit
SUBSYSTEM=="usb", ATTR{idVendor}=="0d28", ATTR{idProduct}=="0204", MODE:="666"

Then reload the udev rules:

$ sudo udevadm control --reload-rules

If the micro:bit was plugged in, unplug it and then plug it in again.

Now let verify the permissions. Make sure the micro:bit is connected with the USB cable. It should appear as a USB device in /dev/bus/usb.

$ lsusb | grep -i "NXP ARM mbed"
Bus 003 Device 004: ID 0d28:0204 NXP ARM mbed
$ # ^^^        ^^^

In the above example the micro:bit got connected to the bus #3 and got assigned the device #4. This means the file /dev/bus/usb/003/004 is the micro:bit. To check the permissions:

$ ls -l /dev/bus/usb/003/004
crw-rw-rw- 1 root root 189, 259 Mar  7 10:04 /dev/bus/usb/003/004

The permissions should be crw-rw-rw. If they are not, make sure to repeat the udev rules steps correctly.

Install

The following command compiles and then flashes the application on the micro:bit. It first must be connected with a USB cable.

$ cargo embed --release