software

LuLuu! software

LuLuu's software stack is based on the Rust embedded and rp2040 tooling.

The firmware is split into a couple of crates housed in the root Cargo workspace. We provide our own "board support crate", luluu-bsp, and leverage that crate in the actual firmware, contained in the luluu folder.

There is also luluu-enc, a custom animated image encoding format for the LuLuu, and luluu-cli whose main purpose is to convert .GIFs into .LUs which can be read and displayed by the devide.

Using Rust embedded crates:

• rp2040-hal
• embedded-hal
• embedded-sdmmc-rs
• display-interface
• mipidsi

Building and flashing the luluu firmware

In order to build the firmware yourself, you'll need to:

1. Initialize and update git submodules

We vendor some of our dependencies under the vendored directory. Because of this, you'll need to init and update git submodules in order to build.

git submodule update --init

2. Install the latest Rust and the thumbv6m-none-eabi target. First, install rustup. Then,

rustup self update
rustup update stable
rustup target add thumbv6m-none-eabi

3. Install flip-link

cargo install flip-link

Then you can build the firmware by changing into the luluu directory and using cargo build --release. In order to install the built firmware on the LuLuu unit, you have two options.

Installing with elf2uf2-rs

This does not require an ARM 2-wire SWD capable probe, but is a bit cumbersome for live development and does not provide debugging capabilities.

1. Install elf2uf2-rs

cargo install elf2uf2-rs

2. Change directory to the luluu directory within this software directory

cd luluu

3. Put the LuLuu into "USB Bootloader mode". Do this by connecting the unit via USB to your computer, then hold USBBOOT button and press the RESET button. If on Linux, you may need to manually mount the device like you would a USB storage device.

4. Run cargo run --release to build and install the firmware to the device

cargo run --release

Installing with cargo embed

This requires a probe-rs-compatible probe. For example, a RaspberryPi Debug Probe which LuLuu was designed to work with.

1. Install probe-rs

You may need to install prerequisites as well; see this page. If you're on Linux, you may also need to change your udev rules, as specified here.

cargo install probe-rs --features cli

2. Connect the LuLuu unit to power (i.e. plug it into a USB port; the port will not be used for data in this configuration) as well as through its SWD port to your probe.

3. Change directory to the luluu directory within this software directory

cd luluu

4. Run cargo embed to execute the probe-rs session

This compile, flash the device through the probe, and start running a debug session according to Embed.toml.

To flash the fully release, no logging version:

cargo embed --release

To flash a release build but with logging enabled and start a defmt log console

cargo embed probe --release --features probe

This selects the "probe" profile from Embed.toml and enables the probe cargo feature on the luluu crate, which enables its logging functionalities.

You can enable more or less verbose logging by modifying the DEFMT_LOG env variable and luluu/Cargo.toml, for example uncomment the embedded-sdmmc-rs/defmt-log line to enable logging from the library used to communicate with the SD card:

DEFMT_LOG=embedded_sdmmc=trace,luluu=debug cargo embed probe --release --features probe

Converting GIFs with luluu-cli

You can convert animated gifs that are 60x60 or 120x120px in size and <= 15 frames per second into .LU files that are used by the device by using the luluu-cli crate.

1. Change into the luluu-cli directory

cd luluu-cli

2. Run the tool, specifying the convert subcommand and a path to the file.

cargo run --release convert [FILE_PATH]

The tool will write the output file with the same name directly next to the original GIF provided.

You can get more help with

cargo run --release -- -h

or

cargo run --release -- convert -h