pic Chips.

[adrian]

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.

[email protected]

 

[TheDragon]

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 to
8.

If 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.
Remove spaces etc. to reply: n o lindan at net com dot com
psst.. want to buy an f-stop timer? nolindan.com/da/fstop/

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

 

[CWatters]

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?

I would use a standard PC AT/PS2 keyboard...

The protocol is well documented all over the net... Examples..

http://www.beyondlogic.org/keyboard/keybrd.htm
http://panda.cs.ndsu.nodak.edu/~achapwes/PICmicro/PS2/ps2.htm
http://govschl.ndsu.nodak.edu/~achapwes/PICmicro/index.html

and the code you need for the PIC already exists.. Examples...

http://www.electronic-engineering.ch/microchip/projects/projects.html
http://panda.cs.ndsu.nodak.edu/~achapwes/PICmicro/code/ps2/Host.html

The above may not be the BEST examples so find your own. Hint: try posting
on a PIC users forum.

 

[CWatters]

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?

I would use a standard PC AT/PS2 keyboard...

The protocol is well documented all over the net... Examples..

http://www.beyondlogic.org/keyboard/keybrd.htm
http://panda.cs.ndsu.nodak.edu/~achapwes/PICmicro/PS2/ps2.htm
http://govschl.ndsu.nodak.edu/~achapwes/PICmicro/index.html

and the code you need for the PIC already exists.. Examples...

http://www.electronic-engineering.ch/microchip/projects/projects.html
http://panda.cs.ndsu.nodak.edu/~achapwes/PICmicro/code/ps2/Host.html

The above may not be the BEST examples so find your own. Hint: try posting
on a PIC users forum.

 

[petrus bitbyter]

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.

[email protected]

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