EECS 373 Final Project

Wireless Keyboard

by Junson Euh, Pokman Yiu

Group
members

Pokman Yiu

Junson Euh

Project
description

To make a wireless keyboard, our project receives the clock and data signals
generated by the wired keyboard and it uses infrared emitter to send those
signals to the infrared detector. Our program analyzes the data that gets in to
the infrared detector and presents each key pressed through the Windows
HyperTerminal via UART.

Components

The wireless keyboard consists of a wired 102-key ps/2 keyboard, MPC823
board, LM351 to make a voltage follower, LM139 to make a comparator, two
transmitters (Infrared Emitter Diode) and two receivers (Infrared Detector) to
send and receive a clock and a data signals from the keyboard.

Difficulties

We had some difficulties making a circuit. After correctly reading
the signals from the wired keyboard, we have tried to send those signals using
the infrared transmitter to the infrared receiver. However, the signal received
from the transmitter was not a square wave and it was much reduced. We’ve
fixed this problem by making the voltage follower on the transmitter’s
side and voltage comparator on the receiver’s side. While designing the
schematic, due to the different clock signals between the processor and the
keyboard when adding the interrupt signal, we needed to count when the whole
data is being received. Also in the software part, we had some difficulties
dealing with the “break code” (the signal after the key is being
pressed: 0xF0).