control button array

I'm not really clear what you're saying above,

I'd use a PIC (or similar) dedicated to just the keyboard task using two 8 bit ports to do the lot on an 8 * 8 matrix, the serial comms could then be RS232, synchronous, or bit bashed and the PIC would handle debouncing, shift keys, double keypress etc. Simple, configureable, selfcontained and cheap

Mike Harding

Nah. There's a simple part that does keyboard matrix w/debounce:

Check out the MM74C923N Datasheet at

Gary

Yep, that's a good chip I first used it (or maybe it's younger brother in about 85?) but it will only handle 20 keys, not enough for the OPs 49 keys.

Mike Harding

Thanks for all the good feedback.

How about I get a $10 keyboard at Office Depot and hook that up to scan 7x7 ? - RM

If you mean a PC keyboard? Well you could but you would have to butcher it quite a bit and then actually hook your push buttons up in the location/arrangement you require which might? take a lot of time and effort. And then you would need to interface to it (although it's a well documented protocol) and interpret the scan codes etc. I think it needs a clock as well? Personally I'd still go for the dedicated PIC solution providing you can write that sort of software and do the, fairly simple, wiring required.

Mike Harding