> 2nd. Your system is being resetted, first lets see if that's right, then we
> figure out why. Try the following:
> 
> Right on top of main, but once you have configured all ports, put something
> like:
> 
> Bsf portpin
> Delay1sec
> Bcf portpin
> 
> And hook up an LED to that pin so you'll see that secuence everytime your
> system starts. AS you know, you should only see that one time when you turn
> on the system.

Well, it turns out watchdog was not the only source of resets.  I
cannot find where the rest is coming from, though.  Below is the
minimum code that reproduces the problem (basically I poll RCREG until
I get something, then toggle the state of a led).  I *guess* a reset
is what's happening because, if all went well, the led should be
turned on by sending one byte to the serial, then turned off with
another byte, and so on.  Instead, it only flashes briefly whenever a
byte arrives.  Can anyone point me in the right direction?  (other
debugging techniques more than welcome as well).


        list    p=18f458
        include "p18f458.inc"

        __config _CONFIG1H, _HS_OSC_1H
        __config _CONFIG2H, _WDT_OFF_2H
        radix   dec

LEDPIN  equ     0
LEDPORT equ     PORTB
LEDTRIS equ     TRISB

_main
_setup_io
        bcf     LEDTRIS,LEDPIN
        bcf     LEDPORT,LEDPIN
_setup_serial
        movlw   25              ; 9600 bps when clock @20Mhz
        movwf   SPBRG
        bsf     TXSTA,BRGH      ; high speed
        bcf     TXSTA,SYNC      ; async
        bcf     TRISC,6         ; rc6 output
        bsf     TRISC,7         ; rc7 input
        bcf     RCSTA,RX9       ; 8-bit receive
        bsf     RCSTA,SPEN      ; serial port enable
        bsf     RCSTA,CREN      ; enable receiver
_loop
_get_char
        nop
        btfss   PIR1,RCIF
        goto    _get_char
        movf    RCREG,W
        btg     LEDPORT,LEDPIN
        goto    _loop

        end

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