Lotus LED Matrix Module

It's a 9x34 (306) LED matrix, controlled by RP2040 MCU and IS31FL3741A LED controller.

Connection to the host system is via USB 2.0 and currently there is a USB Serial API to control it without reflashing.

Rust project setup based off of: https://github.com/rp-rs/rp2040-project-template

Features

• Reset into bootloader when firmware crashes/panics
• API over USB ACM Serial Port - Requires no Drivers on Windows and Linux
  • Display various pre-programmed patterns
  • Light up a percentage of the screen
  • Change brightness
  • Send a black/white image to the display
  • Send a greyscale image to the display
  • Go to sleep
  • Reset into bootloader
  • Scroll and loop the display content vertically
  • A commandline script and graphical application to control it
• Sleep Mode
  • Transition slowly turns off/on the LEDs
  • Current hardware does not have the SLEEP# GPIO connected, can't sleep automatically

Future features:

• API
  • Send a greyscale image to display
  • Read current system state (brightness, sleeping, ...)

Control from the host

Requirements: Python, PySimpleGUI and optionally pillow

Use control.py. Either the commandline, see control.py --help or the graphical version: control.py --gui

options:
  -h, --help            show this help message and exit
  --bootloader          Jump to the bootloader to flash new firmware
  --sleep, --no-sleep   Simulate the host going to sleep or waking up
  --brightness BRIGHTNESS
                        Adjust the brightness. Value 0-255
  --animate, --no-animate
                        Start/stop vertical scrolling
  --pattern {full,lotus,gradient,double-gradient,zigzag,panic,lotus2}
                        Display a pattern
  --image IMAGE         Display a PNG or GIF image in black and white only)
  --image-grey IMAGE_GREY
                        Display a PNG or GIF image in greyscale
  --percentage PERCENTAGE
                        Fill a percentage of the screen
  --clock               Display the current time
  --string STRING       Display a string or number, like FPS
  --symbols SYMBOLS [SYMBOLS ...]
                        Show symbols (degF, degC, :), snow, cloud, ...)
  --gui                 Launch the graphical version of the program
  --blink               Blink the current pattern
  --breathing           Breathing of the current pattern
  --eq EQ [EQ ...]      Equalizer
  --random-eq           Random Equalizer
  --wpm                 WPM Demo
  --snake               Snake
  --all-brightnesses    Show every pixel in a different brightness
  --serial-dev SERIAL_DEV
                        Change the serial dev. Probably /dev/ttyACM0 on Linux, COM0 on Windows

Examples

# Launch graphical application
./control.py --gui

# Show current time and keep updating it
./control.py --clock

# Draw PNG or GIF
./control.py --image stripe.gif
./control.py --image stripe.png

# Change brightness (0-255)
./control.py --brightness 50

Building

Dependencies: Rust

Prepare Rust toolchain:

rustup target install thumbv6m-none-eabi
cargo install flip-link
cargo install elf2uf2-rs --locked

Build:

cargo build

Generate UF2 file:

elf2uf2-rs target/thumbv6m-none-eabi/debug/led_matrix_fw led_matrix.uf2

Flashing

First, put the module into bootloader mode, which will expose a filesystem

This can be done by pressing the bootsel button while plugging it in.

cargo run

Or by copying the above generated UF2 file to the partition mounted when the module is in the bootloder.

Panic

On panic the RP2040 resets itself into bootloader mode. This means a new firmware can be written to overwrite the old one.

Additionally the panic message is written to flash, which can be read as follows:

sudo picotool save -r 0x15000000 0x15004000 message.bin
strings message.bin | head