This application note describes the construction of a
low cost serial programmer which uses a PC with a parallel
(Centronix printer) port to control a PIC16C84.
This programmer has the capability of programming a
PIC16C84 microcontroller, and reading back internal
data without removing the device from the target circuit.
This feature is very useful in applications where
changes in program code or program constants are
necessary to compensate for other system features.
For example, an embedded control system may have to
compensate for variances in a mechanical actuator’s
performance or loading. The basic program can be programmed
and tested during design phase. The final
program and control constants can be easily added
later in the production phase without removing the
microcontroller from the circuit.