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

[Bernd Walter]

On Wed, Nov 18, 2009 at 05:21:25PM +0100, Ole Reinhardt wrote:
> Hi Ulrich,
> 
> > I come back to your code next week. I'd like to implement PDC/DMA for 
> > the network and the SPI channels. If supported, I'd like to implement it 
> > for a background memcpy too.
> 
> Background memcopy won't work, as the PDC does not support
> memory<->memory dma.

Not directly, but there are IO functions which have internal loopback
support - at least USART would do.
Unless you use that function for real IO it can be harnessed to
copy data.
But you need to be carefull - byte level IO does byte access to memory,
while a CPU driven copy would access long words.
Depending on the actual overhead for reading opcodes it might be
less efficient.

-- 
B.Walter <bernd at bwct.de> http://www.bwct.de
Modbus/TCP Ethernet I/O Baugruppen, ARM basierte FreeBSD Rechner uvm.