Hi,
two additional remarks:

the 1st line is bogus even if you want to set OSCCAL manually, as the
statement

        movfw   0x1ff

makes no sense.

> >        movlw   .100            ;  Rtcc = 225

It will load decimal 100 to W instead of 225 or whatever you intended.

I hope this helps.

Regards,

Imre


On Wed, 17 Nov 1999, J Nagy wrote:

> Graham North wrote:
>
> >I am have problems with a simple program to make leds flash with a 508.  The
> >program simulates correctly, but when programmed the chip does nothing.
> >
>
> Offhand, ignoring syntax that I'm not familiar with, I can see two things
> that I'd look at:
>
> >        org     0x00            ;Start of code space
>
> >;************************** Main ********************************
> >
> >        movfw   0x1ff
> >        movwf   OSCCAL          ;Set oscillator calibration reg.
>
>
> Microchip has been kind enough to place a MOVLW <osccal const> at location
> $1FF, the startup vector, for you. When the chip reaches location $000, all
> you need to do is MOVWF OSCCAL (if you intend to use the internal
> oscillator). Eliminate your first line.
>
>
> >Wait_5ms                        ;do
> >        movwf   RTCC
> >Timer_check                     ;do
> >        movf    RTCC,W          ;  read Rtcc
> >        btfss   STATUS,Z
> >        goto    Timer_check     ;while (Rtcc<>0)
> >        return
>
>
> You've defined RTCC as register 8, but don't do anything with it for it to
> ever become zero. Were you perhaps thinking of register 1 (TMR0)?
>
> Hope this has been helpful,
>
>
>         Jim Nagy
>         Elm Electronics
>   ICs for Experimenters
> http://www.elmelectronics.com/
>
>