RetroBSD is UNIX running on PIC32 and this is a board I designed for it, evolving into tiny computer
Test of cheap chinese keboard as per https://hackaday.io/project/643-minibsd-laptop-computer/log/32588
47.06 MB 02/24/2016 at 09:26
Though the old Tesla keybaord I described here and here and described by @Benchoff in #Metal Dome Keyboard is still in my drawer in amount higher than small, I'm looking for alternatives for my MiniBSD.
I found one in here, for the case the listing is unavailable, here is screenshot
I dissected the thing on arrival and didn't bother whether it works or not
There is nothing but 20x8 cm keyboard matrix with 28-pin 1mm pitch FPC connector and tiny PCB containing USB controller
With the testing pads it looks like perfect breakout board for testing, after cutting the epoxy blob. The keyboard itself looks quite usable and has nice feel
there are rubber domes under each key and mechanical support
There are 25 pins used on the 28-pin flex cable, checking all the combinations manually with multimeter would be quite annoying, so I decided to build a test rig.
Not the cleanest example of engineering work, but for quick testing it is adequate. There is PIC16F1519 on board, testing all combinations of wires for conductivity few times per second and pushing results via serial port. Not exactly interesting thing, but quick and ugly test sources will be available for download in the "files" section.
After a few minutes of poking the keys and noting the results, I got this nice table
where line 11 is unused, being apparent on pictures above - or translated into keyboard layout
For example, pressing key Q connects lines 20 and 7.
Well, it's a long time since last update. Today, I sat down to my new board around PIC32MZ2048ECG064
and configured/complied/loaded LiteBSD system to run on it from internal RC oscillator
Copyright (c) 1982, 1986, 1989, 1991, 1993 The Regents of the University of California. All rights reserved. 4.4BSD-Lite build 0 compiled 2015-12-28 jarin@plechac:LiteBSD/sys/compile/SDZL.pic32 cpu: PIC32MZ2048ECG064 rev A5, 200 MHz oscillator: system PLL div 1:2 mult x50 cache: 16/4 kbytes real mem = 512 kbytes avail mem = 352 kbytes using 18 buffers containing 73728 bytes of memory spi1 at pins sdi=RF1/sdo=RF0/sck=RD1 spi2 at pins sdi=RG7/sdo=RG8/sck=RG6 spi3 at pins sdi=RB9/sdo=RB3/sck=RB14 spi4 at pins sdi=RD11/sdo=RD0/sck=RD10 uart1 at pins rx=RD2/tx=RD3, interrupts 112/113/114 uart2 at pins rx=RB7/tx=RB6, interrupts 145/146/147, console sd0 at port spi2, pin cs=RG9 sd0: type I, size 498176 kbytes, speed 12 Mbit/sec sd0a: partition type b7, sector 2, size 204800 kbytes sd0b: partition type b8, sector 409602, size 32768 kbytes sd0c: partition type b7, sector 475138, size 102400 kbytes bpf: lo0 attached WARNING: preposterous clock chip time -- CHECK AND RESET THE DATE! starting file system checks. /dev/rsd0a: 2128 files, 13973 blocks used, 36242 free /dev/rsd0a: MARKING FILE SYSTEM CLEAN starting network clearing /tmp standard daemons: update. Mon Dec 28 15:44:43 PST 2015 4.4BSD-Lite (bsd.net) (console) login: root Last login: Mon Dec 28 15:44:00 on console Copyright (c) 1980, 1983, 1986, 1988, 1990, 1991, 1993, 1994 The Regents of the University of California. All rights reserved. 4.4BSD-Lite UNIX #1: Fri Apr 01 00:00:00 PDT 1994 Welcome to 4.4BSD-Lite! erase ^H, kill ^U, intr ^C status ^T Don't login as root, use the su command. #
This is more powerful system than previous one with PIC32MX - only 128kB RAM / 80MHz compared to 512kB RAM and 200MHz of PIC32MZ, not mentioning new OS, so I'm definitely going to employ this MCU on MiniBSD computer.
Well... four months since last update... the time flies. Brian Benchoff asked about the new keyboard layout, so here is my quick and dirty "drawing" in LibreOffice Calc.
When Q key is pressed, there is contact on between pins 1 and 6. After pressing J, between 9 and 14. You got the idea.
It is not very likely to obtain the keyboard outside Czech or Slovakia, though Brian got this keyboard in Apex electronics, LA. However, I managed to get my hands on a few pieces of those keyboards, so I'll be able to source it to interested builders, if any.