[hpsdr] [FPGA_USB] Review/Comments FPGA_USB Board - April 5, 2006

[Eric Blossom]

On Fri, Apr 07, 2006 at 10:04:22AM -0400, Philip Covington wrote:
> ***** High Performance Software Defined Radio Discussion List *****
> 
> Hi Chris,
> 
> I have mixed feelings about the external RAM for the FX2.  The "A"
> version contains 16 k of internal RAM.  I would think that most of the
> functionality of the board will come from the FPGA and not the FX2. 
> In that case I don't see the need for additional RAM.  I used the 128
> pin version of the chip because it is usually in stock where the 56
> and 100 pin versions vary in availability.  Right now the external RAM
> is not used... but I could be convinced (with a good argument) to add
> support for it so it could be optionally populated on the board.


I don't think you'll need it.  The earliest USRP prototypes had it,
but we never used it, and dropped it from the design.  The current
USRP FX2 firmware is ~6KB.

Eric

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