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mcmatterson | 2 years ago

I have this exact kit hosting my house's RPi server!

A couple of things:

0. The physical quality of this build is out of the world good. PCB, plastics, switches, it's all amazing

1. The software as provided has a pretty old school build process (part of the charm?). I tightened up a bunch of it and dockerized it at https://github.com/mtrudel/pibox/tree/main/pidp11

2. I wish the build would have used something like an MCP23017 for IO instead of claiming so many RPi GPIOs. There's only a few (2-3 IIRC) GPIOs unused by the front panel, and the matrix LED/switch scan setup burns a ton of CPU

discuss

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sleepytimetea|2 years ago

I read his description of the LEDs being powered by brute force looping...even though he uses a buffer IC, the CPU still does the monotonous and continuous looping to keep the LEDs intermittently supplied with current.

I wish he had used a few MAX7219 LED driver ICs - they just need 4 IO pins, can be chained together, and don't need any maintenance CPU cycles unless a change in config is desired.

They also ensure perfect brightness control, and are current controlled LED drivers instead of using 330 Ohm resistors that waste power...all power goes to illuminating the LEDs and none is wasted as heat in resistors.

Maybe I should write him and offer my help in switching for the next spin of the PCBs.