Jan-Erik Soderholm wrote:
> 
> 
> Nick_F wrote:
>> As far as I know, a 20MHz PIC16F628A can have a resolution of 200nS,
> 
> Exactly what do you meen with "resolution" ?
> 200 ns is the fastest instruction time, but that doesn't
> give you any practical "resolution" in most applications.
> 
> 

Yes, sorry. I was thinking about the duration of a one cycle instruction.
The shortest pulse I can generate with a 20MHz clock has 200ns and by using
the following code, the period of a complete cycle has 800ns.

Loop	
	bsf	LEDPORT,	LED	;turn on led for 200ns (1 cycle)
	bcf	LEDPORT,	LED	;turn off led for a total of 600ns (3 cycles with goto)
	goto	Loop			;go back and do it again


If I want a 50% duty cycle, I can generate a 1.2us pulse using this method
(add two nop after bsf).
I know it is very crude, I try to improve the code.

Regards,
Nick




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