Keyboard Controlled Collision Free Tank

Jeff Shattock
Vincent Chamasrour

For this project, we interfaced with an AT keyboard and used it to control a tracked tank vehicle.  The keyboard lines are bidirectional serial communication lines.  The majority of the communication with the keyboard was done in hardware, through the use of a shift register.  This was made easier by the fact that the keyboard generates its own clock signal, and only generates the clock when data is being transmitted on the data line.

In addition, an ultrasonic range finder was mounted on the front of the tank to ensure that it did not run into anything.  The range sensor produces a PWM signal with a duty cycle proportional to the distance from the sensor to the nearest object.

The most difficult part of this project was the fact that the keyboard lines, being bidirectional, use open collector drivers.  This departure from standard totem pole TTL drivers required the use of external transistor drivers to ensure proper levels on the line.