Michael Rathbun wrote :

> >> >R-M-W ?
> >> 
> >> The LEDs in question are pulled high through 100 ohms by port 
> >> c lines, and the software PWM output is done with bsf and bcf
> >> instructions during the timer1 interrupt.
> >
> >Thought so, that's why I thought you had got hit by the
> >r-m-w problem. Try to update a "shadow" register with
> >bsf/bcf first, then update all LEDs at the same time
> >using (e.g.) a MOVWF.
> 
> Bear in mind that the failure only occurs when running at 20 
> MHz in that particular board.  Run at 4 MHz or in any of the other 
> prototype boards  here, and there is no issue.

No, of course !
That's expected *if* you're running into r-m-w problems !!

Just so there isn't any missunderstandings here, you *do* know
what the r-m-w problem is, right ?

Jan-Erik.
> 
> >In general, be carefull with bit write operations on PORTs.
> 
> Indeed.  For hardware test routines, however, I try to be as 
> careless as possible (anent the "turn off all your graceful failure 
> handling during test" advice in another thread). And in this case,
> it paid off.

In what way "paid off" ??

Jan-Erik.



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