Re: Tiny ARM Development

Hi,

> etc. Merely reading and writing to I/O ports, which I'm just
> *assuming* are available on the chip, is proving no readily documented
> task. I haven't even been able to find a detailed instruction set
> list.

All I/O is memory mapped, ARM does not have a separate I/O address
space. While I haven't worked with the 91SAM series (yet) all this
stuff was adequately documented for the 91R40* series parts.

The instruction set documentation is published by ARM, not Atmel, but a
copy can be found under AT91 ARM Thumb - Other Documents at
<http://www.atmel.com/dyn/products/other_docs.asp?family_id=605>
(ARM7TDMI Technical Reference Manual).

> It simply needs to read ports when an external interrupt is triggered,
> and output on other ports the rest of the time (with some memory used
> as a cache in between these operations).

This is an interesting sort of requirement. I'm not sure that ARM was
necessarily the obvious choice here - its interrupt latency is not
fantastic. Have you done actual metrics yet? Are you committed to a
board layout, or are you experimenting on the EVB before starting the
layout?

.

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