pico-pbm2ssd1306
MOVED! Hello, I am moving my repos to http://ratfactor.com/repos/ and setting them to read-only ("archived") on GitHub. Thank you, -Dave
This repo contains two things:
-
A Zig program that converts 1-bit ASCII PBM images (easily created in many different raster graphics programs such as GIMP).
-
A Pico (RP2040) microcontroller program to receive images via UART serial connection and display them on a 128x64 pixel OLED screen controlled by the common SSD1306 chip. This program is written with the official Pico C SDK.
You can see these programs in action in the later part of my 2023: Year of the Microcontroller "chapter" here:
https://ratfactor.com/mc2023/chapter4
PBM converter (runs on a host computer)
The SSD1306 display RAM expects image data as 1-byte columns where each of the 8 bits in a byte is a pixel in the column. There are 128 of these 1-byte columns per row. These rows are called "pages" and there are 8 of them total on the display for 128 x 64 pixels total.
The PBM ASCII 1-bit image format is easily written (even by hand!) and read with any text editor.
The convert.zig program takes a PBM image on STDIN and writes a binary
image in the format expected by the SSD1306 to STDOUT.
zig run convert.zig <foo.bpm >foo.bin
The viewer.zig program takes a converted SSD1306-compatible binary
image on STDIN and displays it as ASCII characters in the terminal.
zig run viewer.zig <foo.bin
You can also convert and view in one go by piping the converter output to the viewer like so:
zig run convert.zig <foo.bpm | zig run viewer.zig
(You'll note that I'm running these programs as if they were scripts for rapid testing and debugging purposes, but, of course, you can compile them with Zig and run the compiled executables.)
Pico SSD1306 init and image display via UART (runs on microcontroller)
These three files make a complete Pico C SDK-based program to run on the microcontroller and display images on an attached OLED screen:
pico_sdk_import.cmake
CMakeLists.txt
oled3.c
(Sorry about the filename. It happens to be the third program I wrote for this OLED device.)
To compile, you'll need to do the cmake dance:
mkdir build
cd build
cmake ..
cd ..
make
Setting up the SDK and getting the compiled program onto the Pico are beyond anything this README could hope to cover, but the Raspberry Pi people have that part well covered.
To send a converted binary image to the device, you can do something like this on a Linux machine connected via UART:
stty -F /dev/serial0 9600
cat foo.bin > /dev/serial0
Good luck!