Re: [Discuss-gnuradio] USRP and USB full speed (1.1) transmit

[Philip Balister]

> Remember that the GPIF is currently set up to DMA 256 16-bit values.
> Perhaps that part needs changing.  The magic value is probably buried
> in the WaveData table in usrp_gpif.c

I looked over the GPIF stuff with the Cypress tool I do not see any
reference to transfer size in there. I am thinking the transfer size
is set in the FPGA?

> Another thing you could try is to set up the GPIF in a non-flowstate
> mode.  You'd need to use the Cypress tool to do this (or Larry
> Doolittle's perl (?) code.  Running in full speed, you don't need to
> be able to burst data at 96MB/sec between the FX2 and FPGA.

Do you have any idea what sort of changes to the 8051/FPGA code are
involved? The machines I am using this with do not need high data
rates (in fact more decimation in the FPGA would be helpful).

> Philip, do you have access to a logic analyzer?
> It would extremely helpful for determining what's really happening
> between the FX2 and FPGA.

Agreed. Unfortunately, we are a communication group, not a digital
hardware group. So we do not have a logic analyzer. Of course, these
days, it is hard to tell the difference between a comm group and a
digital hardware group.

Philip

> Eric