[gta02-core] Wasting valuable pins (Was: PMU cleanup)

Rask Ingemann Lambertsen ccc94453 at vip.cybercity.dk
Wed Aug 26 11:57:19 CEST 2009

On Tue, Aug 25, 2009 at 09:02:15AM -0300, Werner Almesberger wrote:
> Rask Ingemann Lambertsen wrote:
> > Other such examples are the DMA interface and the camera port.
> I know that you like the camera port :-) But a good use for the DMA
> interface is new to me. What would you do with it, considering that
> all the address and data lines are buried somewhere in the PCB ?

   You can read/write the GPIO ports so as to have an efficient means of
getting data into or out of the device. We should have at least one
nXDREQ/nXDACK pair available at test points or the debug connector for
syncronisation with an external device. But you need to have the GPIOs in
the same GPIO port and byte aligned to make use of the DMA interface, not
scattered everywhere as in GTA02.

   One possible use would be a 13-bit logic analyzer, using GPIO port J
(camera port). You could sync with nXDREQ, clock from internal clock sources
or from TCLK0/GPB4 (which I'll route to the debug connector as a substitute
for CAMDAT4/GPJ4).

Rask Ingemann Lambertsen
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