There is not much that can be said about this board. The heart of
the circuit is the microcontroller, manufactured by a company called Elan
(see the link to their web site on my home page). Pins 1 and 24 of
the controller will talk to the sonar board via SK5 pins 4 and 5.
Resistors R6 and R7 act as pull-up resistors for the two transmission
lines. The processor clock is supplied by a single resistor, R8.
Normally, a resistor and capacitor would be used to generate the clock.
However, you can get away with using just a resistor, and relying on the
stray capacitance between the pin and ground.
Capacitor C2 is connected to the +5V
supply and the VDD pin. It acts as a low pass filter, filtering out
any noise or spikes that may appear on the supply. Resistor R9
connects pin 13 of the processor to the buzzer, via PL3 and the Light IO
board. it is there to limit the current being drawn by the buzzer,
so that the processor is not damaged.
PL3 connects directly to the Light
IO board, and then through to the Motor Control board. SK5 will
connect directly to the Sonar Processor board.
