gnupic: gpsim / TMR0
Subject:
gpsim / TMR0
From:
Tobias Schlottke ####@####.####
Date:
7 Feb 2005 12:40:10 +0000
Message-Id: <Pine.LNX.4.58.0502071323260.3577@ws-toby.Netzwert.AG>
Hi
I dont understand the behaviour of TMR0 and gpism.
It seems to me thet the timer is not incremented every
cycle. Instead in conditional and/or goto instructions
one increment is missing.
My testbed looks like this:
I'm simulating a 12c508. For testing I wrote this
stupid little program:
========= 8< =====================
;; test.asm
;; assemble with: gpasm -p p12c508 test.asm
include "p12c508.inc"
org 0
movlw 0
OPTION
main:
nop
nop
nop
nop
goto main
end
========= 8< =====================
TMR0 is configured to be incremented every instruction
cycle, (prescaler == 0).
I started the simulator, gpsim version 0.21.2, loaded
one processor and the little prog:
gpsim> processor p12c508
gpsim> load -s test.cod
and ran over the initial part with
gpsim> step 4
.....
wrote: 0x00 to OPTION
0x0000000000000003 p12c508 0x0002 0x0000 nop
Now I check tmr0:
gpsim> dump s
000 indf = 00 001 tmr0 = 01 002 pcl = 04
003 status = 18
004 fsr = 00 005 osccal = 00 006 gpio = 00
Value is one, ok.
Doing one further step and dumping again:
gpsim> step
0x0000000000000004 p12c508 0x0003 0x0000 nop
gpsim> dump s
000 indf = 00 001 tmr0 = 01 002 pcl = 05
003 status = 18
004 fsr = 00 005 osccal = 00 006 gpio = 00
tmr0 ist still 1
??
Either I didnt understand the behaviour of tmr0 or the
simulator doesnt work correctly.
Someone a hint for me?
Toby
