There is a nice little led matrix moard from PIMORONI, “SCROLL PHAT HD”. The form factor is for the pi zero, but it runs well also with a pi 3.
scratchClient offers support for this board.
The interface allows to set pixel with brightness, write large and somewhat smaller text and of course clear the display.
There is a sample scratch script in scratch/scrollphathd/scroll_phat_hd.sb
There are quite a few commands from scratch which need parameters.
This is not a trivial task with scratch. Here a variable is used as a ‘command’-Variable ‘sph_command which receives operation names optionally with parameters.
There are two text variables provided with a 5*7-font and a 3*5 font. Not all chars are supported. The 5*7 font basically supports ascii, the 3*5 font supports digits and some extra chars as ,;.:-_+\/.
The fonts are defined in ‘pseudographics’ in a python file and can easily be expanded.
There is a sample config file available, start scratchClient with
cd ~/scratchClient python src/scratchClient.py -c config_scrollphathd
The adapter code has been written based on code from pimoroni.