High temperature control and display by dedicated microprocessor

摘要

As useful as the pic16c71 chip is, it still suffers from having a limited number of input/output pins. There are eight I/O pins on port B and five on port A. With two of the port A pins used for A/D inputs, as is necessary for temperature control, this leaves only three port A pins for other I/O work. In the high temperature application, we would like to be able to display the current temperature as well as control it. This means that we need four I/O pins to use in strobing the four display digits that are necessary for temperatures up to and beyond 1200℉. In addition we need at least one more I/O pin to control the triac that provides the heater switching. Thus the PIC16C71 falls short of enough I/O pins for the task, although it is perfectly capable in all other respects.