Page 313 - Making PIC Microcontroller Instruments and Controllers

DEBUGGING

General

It takes a long time to become a good debugger It has taken me forcvet, and I am still
leaming and still not very good at it. The ploblem is that you must have a good under-
standilg of the PIC you are using and come up with a solid design. Though this may
seem pretty straightforward, it isn't, especially if you are using a new PIC and rhe PIC
16F877Awe are discussing is new to most ofus.
In plain English, this means that I really do not know how to tell you to become a
good debugger. Even so,I need to give you some guidance to help you, so I have put
down everything that came to mind as I was debuggilg the various projects in this book.
In these paragraphs,I have allowed myself some repetition uDder the vadous headings
so they can each stand alone.
At the end of the chapter, I have included some questions and answofi that werc the
result of some discussions on the Web site for another Droiect but that are also relevant
to any discussion about the 16F877A PIC.

Debugging and Troubleshooting

Debugging is not a random process during which one mighl hope to get lucky. It is a
very carcfully thought out stratregy to find out why a program is not behaving the way
it was intended to and what needs to be done to conecttheqoblem. Yourri havefued
the problen only if yolt can make the problem come back b! undoing the ft. A \ag.te
suspicion that you might have fixed the problem by pressing on a warm component is
not enough to conclude that lhe prcblem has actually be€n solved. You must be able to
make the problem come back. This is exacdy the reason why intermittent prcblems are
so hard to nx. lt's had io make them come and go on command. In other words, it is
harder to clearly understand the problem because it is htermittent.

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