"Key" Project

Wiring a switch matrix keyboard to a PICmicro® microcontroller is not that difficult a task - probably the most difficult part of the exercise is figuring out how to wire the two devices together. This is probably the one project that you will not be able to reproduce exactly, as I believe the keyboard I used was unlabeled (except for a "General Instruments" stamp on the back) and a marking of "Pin 1" on the ribbon cable that came out of the end of it. In the text for this experiment, I review how I figured out how this switch matrix keyboard was wired and how I arranged the I/O pins for wiring to the PICmicro.

Click Here to look at the application's source code.

The circuit used for this application is:

The bill of materials for this application is:

Part Description

PIC16C57 PIC16C57-JW

7805 78L05 +5 Volt Regulator

MAX232 Maxim MAX232 RS-232 Interface Chip

4 MHz 4 MHz Ceramic Resonator with built in 27-33 pF Capacitors

10K 10K, 1/4 Watt Resistor

10K x 8 10K Common Tap, 9 Pin "SIP" Resistor

10uF 10uF, 16 Volt Electrolytic Capacitor

5x 1.0uF 1.0uF, 16 Volt Capacitor (Any Type)

RS-232 Connector 9 Pin, Male D-Shell Connector with Solder Tail Connections

Miscellaneous Switch Matrix Keyboard, Breadboard Prototyping System, Wiring