nICE one why not use another pic? ok. not as cheap as the diodes but cheaper than you could emulate a PC keyboard put infrared link as well,but hell if you are into pic's then they are the only thing to use........... ----- Original Message ----- From: Mark Newland To: Sent: Sunday, March 26, 2000 6:15 PM Subject: Re: how can I only uses 5 cpu I/O pin for 16 keyboard keys input? | I have to wonder sometimes when someone asks this type of question. | | 1) Are they just sooooo new that they don't know what kind of trouble they | are getting themself into? | | 2) They have LOTS of diodes laying around and too broke to afford the IC's? | | 3) They want us to do their homework for them?? | | "Paul B. Webster VK2BZC" wrote: | | > Wing Kent Kwan appears to have written: | > | > > how can I only uses 5 cpu I/O pin for 16 keyborad keys input? | > > My means is No use IC to do it! | > > only use the diodes to do it? but I don't know how to connected it? | > | > Fairly simple. Each key goes to ground, each CPU line has a pull-up. | > Each diode in the matrix goes anode to CPU pin, cathode to key. |