> So there is a point. I don't use any chips with programmed 
> i/o so I didn't realize this was a problem. I think though as 
> the chip gets larger and more powerful it also becomes more 
> abstracted from the low level hardware; thus you don't 
> generally have to do as much bit fiddling.

Depends (of course) on how you use the chip. The 'minicomputer
replacement' type of use generally won't do much bit banging, often the
on-chip or on-pcb hardware peripherals will do the job. But at the other
end of the spectrum the 'logic replacement' type of use often requires a
lot of bit banging, unless all such tasks can be done by hardware
peripherals. Murphy often makes sure that this is not the case.

Think of SPI. A lot of PICs (and other chips) have SPI, but often tied
to specific pins, and you must adhere to how the hardware peripheral
thinks SPI should be used. No luck if for instance you want to handle
two or more SPI periherals in parallel to achieve the best overal speed
(clocks and enables shared, in my case data in also shared, data out
separate).

Wouter van Ooijen

-- -------------------------------------------
Van Ooijen Technische Informatica: www.voti.nl
consultancy, development, PICmicro products
docent Hogeschool van Utrecht: www.voti.nl/hvu
 
 

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