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Registered: ‎11-13-2007

OPB IPIF Scatter/Gather DMA problem

Hi, I have a custom peripheral that I created in EDK 9.1i.  It is a packet oriented communications core (SpaceWire).  So I enabled DMA Scatter / Gather in the OPB IPIF wizard.  I am communicating with the device using a modified Xilinx ethernet driver. 

Things are working fairly well on the test board, but sometimes the received packet is split into two buffers, even though the first buffer descriptor has enough space to hold the entire packet.  The first RX Buffer has the first 4 bytes and the 2nd buffer contains the remainder of the packet.  I would like to see it arrive in a single buffer so that the software doesn't have to reassemble the packet.

In simulation this doesn't happen, only on the board.  I am using OPB IPIF version 1.00h.

Any idea how to debug this problem?  I think I'll try chipscope and look at the OPB transactions when the packet is received.  Is there anyway also see inside the user_logic module with chipscope?  Thanks,

Redefine Technologies, Inc
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