Xilinx UG144 manual Using the Client-Side Fifo, Gmii/Rgmii

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Appendix A

Using the Client-Side FIFO

The example design provided with the GEMAC core contains a FIFO used on the client- side of the core. The source code for the FIFO is provided, and may be used and adjusted for user applications.

The 10 Mbps/100 Mbps/1 Gbps Ethernet FIFO is designed for use with the GEMAC and Tri-Mode Ethernet MAC (TEMAC) cores. The FIFO directly interfaces to the MAC client interface providing a buffer between the MAC and the user’s logic. The FIFO implements a LocalLink user interface, (see “Overview of LocalLink Interface,” on page 130) allowing a direct connection to other LocalLink modules or the user’s logic.

The 10 Mbps/100 Mbps/1 Gbps Ethernet FIFO consists of independent transmit and receive FIFOs embedded in a top-level wrapper. Figure A-1shows how the FIFO fits into a typical implementation.

	LocalLink Interface	Client Interface		GMII/RGMII
Xilinx FPGA
	10 Mbps,	1-Gigabit Ethernet MAC
	100 Mbps,
		Core
	1 Gbps
	Ethernet FIFO
Switch or	Tx		IOBs	1000BASE-T	Twisted
				PHY
	FIFO				Copper
Router		Client	GMII
					Pair
		I/F
	Rx
	FIFO
Figure A-1:	Typical 10 Mbps/100 Mbps/ 1 Gbps Ethernet FIFO Implementation

1-Gigabit Ethernet MAC v8.5 User Guide www.xilinx.com 127

UG144 April 24, 2009