This script drives a USB 32×16 led display. Motivation was to use the matrix (initially bought for a planned but never built HTPC) to display the Rakarrack Preset name, some CPU, RAM, process and VU details. Rakarrack doesn’t yet have a way to export the Preset name to an external process, though I found a feature request for this had already been filed.

For now my script monitors a file and shows the first line, the characters that fit as I didn’t want it to scroll.

Below this there are 8 bars, the first two rows are system stats:

[Left] ^ [Right]
Rakarrack ^ CPU usage
Guitarix ^ Memory usage

The bottom two rows are VU meters, VU meters have decaying peak indicators:

Left output (Mbox2 output 1) ^ Right output (Mbox2 output 2)
Left input (Mbox2 input 1) ^ Right input (Mbox2 input 1)

Additionally if the VU meters haven’t read any signal for a while the screen will start scrolling “Lin-Amp” until input is detected. The script is started using an upstart script and if I recall correctly I’ve set Qjackctl to check if the script is running using a jack-start script.

Feel free to highlight any coding errors I may have made, I would love this script to take up less CPU than it currently does. Although I don’t think it’s too bad at the moment. Some more background information can be found in this post.

32x16 LED matrix

32×16 LED matrix

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