On Tue, Mar 2, 2010 at 2:07 AM, Wouter van Ooijen <wouter@voti.nl> wrote:
> =A0> since few of the ARM chips are documented in enough detail
>> to actually write your own peripheral drivers.
>
> Which ones? All chips I checked so far are thoroughly documented.

I think the main issues are:

 * Several different document sources
 * Different peripherals among each manufacturer

So if you want a complete picture of one particular device you have to
pull down several datasheets and refeence manuals from the
manufacturer, then a few reference manuals from ARM to get the
complete picture.  Even then it's confusing - which manual tells you
the interrupt vector for peripheral X?  Well, visit the peripheral
manual, then the device datasheet, then the register/memory map, then
the CPU reference, and eventually, maybe, you'll get your answer.  But
don't forget that you may have to deal with memory mapping, DMA, etc.

Moving from simple 8 bit microcontrollers where everything was in one
datasheet to more complex computers on chips is a significant leap.

The different peripherals from different manufacturers issue is also a
problem.  You can abstract your drivers as much as you like, but
porting is still a surprisingly significant difficulty.

-- =

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