Hello Iain. You probably can, with the use of isolation diodes. 4 sets of 4 x 4 are possible, as well as 1 set of 8x8 foa a MIDI keyboard. I have 1 system with 8x8x4 (256 scan points) digital input matrix and 6x8 (48 Scan points) analog matrix. This is using a 16F877. So it can be done. There are lots of examples in the books for 4x4. Start there and then expand the software after you understand it. Then take the results and send them to a serial output. Then learn how to format the data for MIDI. Use a 4Mhz, 10Mhz or 20Mhz crystal. The MIDI Baud rate will be right on the money, if you have performed the math correctly for the baud rate. If you use a 16F628 or 16F8xx, then the PIC chip has a built in USART, making it a little easier to send MIDI data. Take each exercise 1 at a time, and in a short period of time you will have a complete project. Vern, Sound Research ----- Original Message ----- From: iain duncan To: Sent: Sunday, August 22, 2004 4:48 PM Subject: [PIC] Re: multiple 4x4 keypads to 16f877 or 18f452? > > Really? I'd have thought an 8x8 square with no external parts. Drive the > > rows with portD and read the columns with portB interrupt on change. I'm > > not familiar with MIDI, but certainly I'd have thought the other 17 IO > > lines would be enough to implement it. > > > > As others are fond of saying "engineering is the art of compromise" > > For midi ouput I think I need only one data pin, maybe an extra for > control so that's no biggy. But can I take stock 4x4 keypads and wire > them up 8x8? Problem is, I've never actually wired up a keypad. So while > I want it to be efficient, I'd rather use a less confusing set up then > anything else. Pin efficiency aside, what would be the most beginner > friendly? > > Thanks > Iain > > -- > http://www.piclist.com hint: To leave the PICList > mailto:piclist-unsubscribe-request@mitvma.mit.edu > -- http://www.piclist.com hint: To leave the PICList mailto:piclist-unsubscribe-request@mitvma.mit.edu