Strange PS/2 keyboard adapter behavior

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Strange PS/2 keyboard adapter behavior

Post by ry755 »

Hi! I just built the PS/2 keyboard adapter using an ATtiny85 by following the schematic on the wiki: I have flashed the KeyboardDemo.hex file from that wiki page to my Uzebox. However I seem to be getting some weird issues. Pressing some keys results in printing garbage, and many of the other keys simply do nothing. Pressing the same key twice often results in a different character being printed each time, the letter 'u' and the apostrophe character being the most common.

I have tried reflashing the ATtiny85 with different fuse settings, the "divide clock by 8" setting seems to make a difference in the amount of garbage being printed, but it's still garbage nonetheless.

I have triple checked the wiring and everything looks correct. Unfortunately I only have a single PS/2 keyboard to test this with, it's a cheap HP keyboard (that I know works, I have used it with various computers in the past). Has anyone else ran into this issue before?

EDIT: Turns out I actually needed to set the clock fuse setting to CKSEL=0001, SUT=11, in order to use the internal PLL to get a 16 MHz clock. I originally assumed that I should've been using the default 8 MHz clock, so this should probably be mentioned somewhere on the wiki. It all works now. :D
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Re: Strange PS/2 keyboard adapter behavior

Post by uze6666 »

Great! Hold on to your keyboard then, I'll very soon publish a pretty good use for it!

Btw, what keyboard did you buy?

Also, I just recently made an updated pcb and firmware to support this nice Perixx keyboard. The way it initialize didn't work with the old firwmware. I'll publish the code and pcb very soon.
perixx-kb.jpg (65.71 KiB) Viewed 304 times
kb-pcb.JPG (62.21 KiB) Viewed 304 times
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