Altera 10-Gbps Ethernet MAC MegaCore Function - Manual (Page 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] to dataout_l[35:0]
■ xgmii_sdr[71:36] to 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] to datain_l[35:0]
■ xgmii_sdr[71:36] to datain_h[35:0]
For more information about the ALTDDIO megafunction ports and parameters, refer
to the
ALTDDIO Megafunction User Guide .