Switching options - deluxe version

The switching options and LEDs for the deluxe version are illustrated above.

The PIC16F84 has two input/output ports, Port A and Port B. Each pin of each port has its own LED and push-to-make switches.

Switches SA0 to SA4 and SB0 to SB7 are push-to-make switches for Port A and Port B respectively. Resistors R19 to R31 protect the ports from excess current flow if the switches are pressed when the port pins are configured as outputs. Resistors R6 to R18 are ballast resistors for the LEDs.

Resistors R32 to R44 protect the port pins from excess current flow when they are in output mode and external circuits are connected to them via these resistors.

Note that the resistor values have been selected to provide the best circuit protection that is compatible with letting all aspects of the demo board function satisfactorily. The values are not necessarily those which would be best suited to a stand-alone design for other applications.

Audio output from RA0 is via capacitor C9, to which a pair of high impedance headphones may be plugged via the socket on the PCB.