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Re: [CPROG] En ordentlig timing

On Sat, 03 Nov 2001 20:16:40 +0100, Peter Aagaard Kristensen wrote:

>  >Inputting or outputting any byte from/to port 0x80 (see above for how
>  >to do it) should wait for almost exactly 1 microsecond independent of
>  >your processor type and speed.
>  >
>  >? Er port ikke en ret speciel port? Jeg ved at det ikke gælder for
>  >andre I/O porte, ihvertfald...
> 
> Og lidt længere ned står der:
> Actually, a port I/O instruction on most ports in the 0-0x3ff range
> takes almost
>   exactly 1 microsecond, so if you're, for example, using the parallel
>   port
> directly,
> just do additional inb()s from that port to delay.

Det skyldes vel at in/out instruktionerne skal igennem det "gode" gamle
ISA interface og derfor tager ekstremt lang tid. 

Du kommer nok til at bide i det sure æble og acceptere at din PIC brænder
ikke kommer til at køre fuld hastighed. :( 

Mvh Morten


> - Peter
>

 
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