I want to do a home based project on getting a pic chip to read a keyboard. What kit should I use - is a usb one a good option?
Also what else will I need? Which is best pic chip for such a small project.
snipped-for-privacy@postmaster.co.uk
I want to do a home based project on getting a pic chip to read a keyboard. What kit should I use - is a usb one a good option?
Also what else will I need? Which is best pic chip for such a small project.
snipped-for-privacy@postmaster.co.uk
"adrian" wrote
You don't say what sort of keyboard. If it is a std. 101 key PC style you will need a PIC with lots of I/O. The minimum is
2 * sqrt (# keys) or 21 I/O lines for 101 keys (20 for 100 keys). Mux and demux chips can lower the number of required I/O lines toIf you want n-key rollover you will also need a large chunk (for a PIC) of RAM - as usual you can trade off RAM requirements for program size and complexity.
There are lots of truly awful keyboard scan and debounce algorithms in the public domain, take your pick.
-- Nicholas O. Lindan, Cleveland, Ohio Consulting Engineer: Electronics; Informatics; Photonics.
aren't PC keyboards already serial out? PS2 connector has + _ Data+ Data - tahts it.
all you need to decode is the bit stream from the keyboards controller
"TheDragon" wrote
Ah, yes. It does depend _where_ you want to read the keyboard: is it the IC inside the keyboard, or the chip that receives scan codes from a commercial keyboard assembly.
If you want a table of scan codes, and I think timing, it used to be in the IBM XT (AT?) technical reference manual. IBM used an 8048 (or some such) at both ends of the keyboard cable.
-- Nicholas O. Lindan, Cleveland, Ohio Consulting Engineer: Electronics; Informatics; Photonics.
I would use a standard PC AT/PS2 keyboard...
The protocol is well documented all over the net... Examples..
and the code you need for the PIC already exists.. Examples...
The above may not be the BEST examples so find your own. Hint: try posting on a PIC users forum.
I would use a standard PC AT/PS2 keyboard...
The protocol is well documented all over the net... Examples..
and the code you need for the PIC already exists.. Examples...
The above may not be the BEST examples so find your own. Hint: try posting on a PIC users forum.
"adrian" schreef in bericht news: snipped-for-privacy@posting.google.com...
Guess you'll have to be more specific about what you want. So what kind of keyboard you want to read and what do you want to do with the result? Otherwise you can get a keyboard, connect a PIC to it and pretend it's reading. If you want a standard AT keyboard to be read, there's at least one project on the net that makes a PIC reading an AT-keyboard so you can use the keyboard to control the application in the PIC.
petrus bitbyter
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