On Fri, 27 May 2005 17:49:06 +0200 (MEST), Jan-Erik Soderholm wrote: >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. >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. -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist