'weird behaviour of a 16C84 ...'
While testing the code for a send only serial transmition from
a PIC 16C84 to a PC I noticed something realy odd behaviour of the
programm running on my pic.
It4s consist of a loop which just count4s up a byte in the
range from D'65' to D'126' ( viewable ASCII ) and send this
char to the PC.
the byte is simply incremented with a "incf" instruction.
while testing once, I noticed that i got e.g. "AEIM ..." insted of
the expected "ABCDEFGHI..." - the byte seemed to be not simply
incremented, it was added with 4.
After resetting the PIC the PIC worked "normal" again.
( means sending "ABCDE... )
while I couldn4t make the PIC showing this odd behaviour again,
I4m still wondering how this could happen.
will evetually the incf opcode have the opportunity to increment by two
( caused by a erreanous bit in PGM memory ) ?
Any Ideas ?
Peter L. Peres
On Mon, 19 Oct 1998, Stefan Sczekalla-Waldschmidt wrote:
> while testing once, I noticed that i got e.g. "AEIM ..." insted of
> the expected "ABCDEFGHI..." - the byte seemed to be not simply
> incremented, it was added with 4.
I'm almost certain that by connecting a variable PSU to the PIC and
increasing the voltage very slowly from 0 you will be able to duplicate
this and other strange things ;). The PIC is not alone on this, it's the
state machine that implements the core in the PIC that can assume invalid
states if not reset properly.
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