[En-Nut-Discussion] [Bulk] Re: Nut OS reliable on AT91SAM7X Evaluation Board?

Marcus Jansson jansson.marcus at yahoo.se
Wed Nov 18 15:26:11 CET 2009

Ulrich Prinz wrote:
>> Marcus Jansson schrieb:
>>> I'd like to implement PDC/DMA for the network and the SPI channels. 
>> This can be done, the SPI seem to have a long list of errata associated with the PDC, though.
> Yes, I saw it and I don't like it :) But what should I do, I'd like to 
> get out optimal performance...

All I see is an opportunity clever workarounds.

>>> If supported, I'd like to implement it for a background memcpy too.
>> I can not see how this can be done with the PDC ...hand optimized LDM/STM block copy ... existing
>> slow memcpy()... increasing performance in internal RAM?
> Yeah ... optimization ... CPU driven memcpy ... many different tasks... 
> It's another strategy... DSP ... DMA ... modify the content ... chain 
 > ... pipe ... totally different ... 12MBit ... polling mode No!...

Yes, that should be possible. I wasnt thinking out of the box.
These pipes btwn ETH-unit and SPI are totally different.
The CPU will mostly wait for DMA to be finished! Lots of power left for other
things to do. Very good.


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