gnupic: GPSIM 0.20.14 and PIC18C452
Subject:
GPSIM 0.20.14 and PIC18C452
From:
Scott Gordon ####@####.####
Date:
9 Aug 2002 08:19:10 -0000
Message-Id: <Pine.LNX.4.10.10208091753530.18208-100000@term10.physics.uq.edu.au>
Hi,
I've been using `GPSIM' to try to simulate code for a PIC18C452 chip, and run
into some problems (mostly I believe these are bugs) :
1. gpsim does not accurately display (on the PINS window at least) the correct
direction (input/output) for I/O ports. They always display as inputs, even
when they are set as outputs, and the simulator actually displays the correct
output values.
2. gpsim produces an error message when unsupported SFRs are written to (so
interrupt priority settings, etc), even if they are valid for the processor ..
whereas I think accepting the value (with a warning message), but ignoring it,
would be better. In some cases, a core-dump also appears to result.
3. gpsim appears not to correctly implement writes to the TMR0H register (the
high half of TIMER 0), when it is running in 16 bit mode. According to the
PIC18F452 manual, both halves of the count should update if TMR0H is written
to, followed by TMR0L. When my program does this, only the low byte updates. I
know that it is running in 16 bit mode since the timer correctly counts in 16
bits during the simulation.
Also, I'm curious why PIC18C452 is supported but not PIC18F452, given that (I
think) the difference is basically just the configuration words. It only
matters because I have PIC18F452 chips, but I've had to assemble in gpasm as a
PIC18C452 chip to simulate it (which poses a slight chance of undetected errors)
Thanks in advance for all of the help.
Cheers
Scott Gordon
