UPGRADE YOUR BROWSER

We have detected your current browser version is not the latest one. Xilinx.com uses the latest web technologies to bring you the best online experience possible. Please upgrade to a Xilinx.com supported browser:Chrome, Firefox, Internet Explorer 11, Safari. Thank you!

AR# 9343

Virtex LogiCORE PCI32/33 - SB08 - Data is lost during read/write burst transactions when LogiCORE is supplying data.

Description

Keywords: DWORD, lost, pci, bridge, reference, FIFO, data, SB08, pci_fifo

Urgency: Standard

General Description:
Data is lost during burst transactions when the Xilinx core is supplying data.

This may be seen when a wait state is inserted dynamically by another
agent during a burst transaction. The iwf_move or trf_unload signal
will go inactive during a wait state, but the PCI_FIFO continues to read
one more piece of data than necessary, effectively skipping a piece of data.

Solution

1

The pci_fifo module incorrectly enables the Block RAM modules.

At the bottom of the pci_fifo.v file, there are 3 Block RAM instantiations.
The .EN port is assigned to logic high. This needs to be changed to
the following:

///////////////////////////////////////////////////
// FILE: ./source/parts/generic/pci_fifo/pci_fifo.v

assign #TDEL ram_en = req_norm_wr | req_norm_rd;

RAMB4_S16 bit1500 (.WE(ram_we), .EN(ram_en), .RST(RESET), .CLK(CLK),
.ADDR({4'b0, ram_a}), .DI(DIN[15:0]), .DO(DOUT[15:0]));

RAMB4_S16 bit3116 (.WE(ram_we), .EN(ram_en), .RST(RESET), .CLK(CLK),
.ADDR({4'b0, ram_a}), .DI(DIN[31:16]), .DO(DOUT[31:16]));

RAMB4_S4 bit3532 (.WE(ram_we), .EN(ram_en), .RST(RESET), .CLK(CLK),
.ADDR({6'b0, ram_a}), .DI(DIN[35:32]), .DO(DOUT[35:32]));

2

An updated version of the pci_fifo.v file can be downloaded
from the Xilinx FTP site.

For PCs:
(Xilinx File http://www.xilinx.com/txpatches/pub/applications/pci/sb08_pci_fifo.zip)

For UNIX:
(Xilinx File http://www.xilinx.com/txpatches/pub/applications/pci/sb08_pci_fifo.tar.gz)
AR# 9343
Date Created 05/23/2000
Last Updated 08/06/2001
Status Archive
Type General Article