The PC board has been designed to accept either a PIC16F84A or PIC16F628. We will now present the circuit and program using a PIC16F628. The sub-routines are explained on page 4 and the program is on page 5.
Simon Circuit using a PIC16F628 micro The operation of the circuit has already been covered on page 1. The 4k7 and 27p are not required when the PIC16F628 chip is used. If they are already on the PC board, they will not upset the operation as pins 4 and 16 are configured as port lines RA5 and RA7 in SetUp and configured as inputs. Thus they will not draw any current.
If RA5 is configured as an output and taken HIGH or LOW, the pin will be damaged as it will conflict with the voltage on the 5v rail.