I think we must be talking about different things here... By "multiplexing" I mean the PIC would give col1 power, then check all the rows (if button 1 was pressed, then row1 would be high, but if 17 were pressed, row4 would not be high), then it turns off power to col1, and turns on col2, then row4 would be high (if 17 were pressed), but not row1, then it would turn off col2, and move on to col3...4...5 then it would start over. That works fine, even if two buttons are being pressed in the same column/row. You'd only get phantom signals if you were cycling columns at like 100kHz+, which you wouldn't do for that very reason. ch424
Ah. I was under the impression you'd just connect rows 1-5 to +VCC and monitor columns 1-5 for voltage. My bad. And yes, you could only use one button at a time, but with a 4-bit bandwidth (One bit reserved for clock), you could use multiple words, and have an almost infinite number of buttons. After all, PS/2 is 1-bit, 9600 baud.
i've made one using an old OTP PIC that has all the USB trickery on board. i can give you the code ch424 if you've got time to write it up n publish it.
ive been wanting to see this for a long time, and i have a following on HardForum.com that i can enlist in any way helpfull to you... db25 parallal LPT ports are disapearing off mobos, the modding community realy realy needs this. mod on mate
Thanks for the offer -- sorry I haven't posted the guide yet people. I've got the USB pic, but I'm a bit too busy to work on it at the moment . TheAnimus, I'd love to publish ya code... please could you pm me about it? I'll post more news as it comes... ch424
okay, i was thinking about this, here is what i want to do: the board will have 2 mandatory chips. there will be traces for 6 or 7 more IC's, but it can be functional with out them. we need a PIC chip, and a USB hub, and probably some sort of LM regulator... the USB hub will have 1 port for the pic, 1 port for a USB-DB9 serial, 1 port for USB-DB25 parallel, and 1 spare port. the pic will have the option of controlling (depending on what parts you buy/solder on): a 5x5 keypad matrix (line & column) scan chip, serial interface up to 2 MAXIM 8x4 LED array drivers, serial interface up to 2 quad high current 12v line drivers w/pwm support, serial interface up to 2 quad channel 0-5v AD (idiot proofed, ect), serial interface and a 2 channel digital POT for controlling the backlight and contrast of the LCD hooked up to either the serial or the parallel port all of these must be independent of each other, so that people only have to buy the parts that they need. is this even possible? feedback? im a fairly confident that i could wire it together, but i have no idea how to begin coding it for windows... im guessing it would take one hell of a DLL, or something, i really don’t know. but in the end, it could be a really useful tool for anyone looking to do custom mods
Thanks for the comments everyone, but sorry people, you're gonna have to wait til September/Novemer, when I can do this at school! I promise I'll post the guide then. ch424
Is there a guide anywhere else on the internet? I'm building a wood case and wanted to fit an lcd screen without paying $100 for a matrix one.
Don't think so, sorry. I made mine by reading the datasheet for the LK204-25 (link might break, matrix orbital change things on a regular basis) then making mine behave in the same way, using an AT90S8515 (Atmel). I then used an FT232BM (from FTDI to convert serial to USB. If you can do it from that info, u r t3h 1337 (and good luck to you ). Otherwise wait 'til November. ch424
Can you upload the hex for 7 buttons (I saw that this one has those seven push buttons instead a rotary encoder...) Thanks.
Holy thread revival batman!!! btw to the OP.. the images are dead.. I bet they haven't been viewed since 2005
