Altera 10-Gbps Ethernet MAC MegaCore Function Bedienungsanleitung PDF herunterladen (Seite 150)

February 2014 Altera Corporation 10-Gbps Ethernet MAC MegaCore Function User Guide

10. Design Considerations

10.1. SDR XGMII to DDR XGMII Conversion

The MAC implements 64-bit SDR XGMII Tx and Rx interfaces with a frequency of

156.25 MHz. The XGMII as defined by IEEE 802.3-2005 standard is a 32-bit DDR

interface with a frequency of 156.25 MHz.

If you want to use the MAC with a PHY IP core and connect it to an external device,

convert the XGMII from 64-bit SDR (156.25 MHz) to 32-bit DDR (156.25 MHz) or vice

versa by connecting the MAC to the Altera DDR I/O (ALTDDIO) megafunctions. The

ALTDDIO megafunctions includes the following features:

■ ALTDDIO_IN megafunction—Implements the Rx interface for DDR inputs to

convert XGMII DDR to SDR frame format.

■ ALTDDIO_OUT megafunction—Implements the Tx interface for DDR outputs to

convert XGMII SDR to DDR frame format.

10.1.1. ALTDDIO_IN Megafunction Configuration

Use the MegaWizard Plug-in Manager to instantiate the ALTDDIO_IN megafunction

and specify the initial parameters. Set the data bus width to 36 bits and apply the

following signal connections:

■

xgmii_sdr[35:0]

dataout_l[35:0]

■

xgmii_sdr[71:36]

dataout_h[35:0]

10.1.2. ALTDDIO_OUT Megafunction Configuration

Use the MegaWizard Plug-in Manager to instantiate the ALTDDIO_OUT

megafunction and specify the initial parameters. Set the data bus width to 36 bits and

apply the following signal connections:

■

xgmii_sdr[35:0]

datain_l[35:0]

■

xgmii_sdr[71:36]

datain_h[35:0]

For more information about the ALTDDIO megafunction ports and parameters, refer

to the ALTDDIO Megafunction User Guide.

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Altera 10-Gbps Ethernet MAC MegaCore Function Bedienungsanleitung Seite 150