[USRP-users] USRP E100 FPGA - OMAP communication

Philip Balister philip at opensdr.com
Mon Sep 9 08:29:04 EDT 2013

On 09/09/2013 06:27 AM, Muez Berhane Reda wrote:
> Dear all,
> I have a question on USRP E100.
> The FPGA sends GPIO interrupts to Gumstix (OMAP) to notify that Data is
> available for it to read.
> How does the FPGA know that the OMAP system have finished
> accessing(reading from) the GPMC CS , so that it can write to that
> memory location again. What is the signaling mechanism used to prevent
> FPGA from writing new samples while the DMA of OMAP is on the process of
> copying the old samples?

There is a large buffer in the OMAP RAM that samples are copied form the
FPGA to memory, so there are multiple destination buffers available for
the fpga to write to. As these buffers are processed by the ARM, they
are returned to the pool of buffers available for the FPGA to write
samples to.


> regards,

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