Post by thread:Interfacing a 3x4 keyboard to the 16C84

I need to interface a 12 key matrix keyboard to the 16C84: which is the best way to do this? Thanks. Bye. ---------------------------------------------- Email: spam_OUTiw2kpuTakeThisOuTradionostalgia.net WWW: http://radionostalgia.net/Users/Lavazza

if you see the book by Douglas Hall (i think its called microprocessors: interfacing hw &sw> you'll get the schematic. of course he uses a 8088, but the idea is the same. if you use a row-column approach, you can even interface 16 keys using 8 I/O pins. see the on-linedata sheets for 12C508 also. they have some info too. > I need to interface a 12 key matrix keyboard to the 16C84: which is the > best way to do this? > Thanks. > > Bye. > ---------------------------------------------- > Email: .....iw2kpuKILLspam@spam@radionostalgia.net > WWW: http://radionostalgia.net/Users/Lavazza >

I had to use one of those keypads once. I was also driving three four phase stepper motors at the same time from an 84. To save pins I used a 74ls138 on porta, three of its ouputs went to the rows of the keypad, and the 4 data bits it produced went to portb. Portb b has pull-ups and the 74ls138 has low outputs so pressing a key brought the pull-ups low, which was very convenient. Also i had 5 other outputs on the 74ls138 which i used to drive 5 seven seg displays and the three stepper motors (using latches of course). On Mon, 30 Jun 1997, Cesare Lavazza wrote: > I need to interface a 12 key matrix keyboard to the 16C84: which is the > best way to do this? > Thanks. > > Bye. > ---------------------------------------------- > Email: iw2kpuKILLspamradionostalgia.net > WWW: http://radionostalgia.net/Users/Lavazza >