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Ixiasoft
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Ixiasoft
4.3.3. Transceiver Clocking and Channel Placement Guidelines in XAUI Configuration
Transceiver Clocking
Input Reference Clock Frequency (MHz) | FPGA Fabric-Transceiver Interface Width | FPGA Fabric-Transceiver Interface Frequency (MHz) |
---|---|---|
156.25 | 16-bit data, 2-bit control | 156.25 |
Transceiver Clocking Guidelines for Soft PCS Implementation
In the soft PCS implementation in the XAUI configuration, you must route xgmii_rx_clk to xgmii_tx_clk as shown in the following figure.
This method uses xgmii_rx_clk to compensate for the phase difference on the TX side.
Without this method, the tx_digitalreset signal may experience intermittent failure.
Transceiver Channel Placement Guidelines
In the soft PCS implementation of the XAUI configuration, you can construct the four XAUI lanes at any channels within the two transceiver banks. However, Altera recommends you place the four channels contiguously to close timing more easily The channels may all be placed in one bank or they may span two banks. The following figure shows several possible channel placements when using the CMU PLL to drive the XAUI link.
The soft PCS implementation of the XAUI configuration has the following channel placement restrictions:
- The channels must be contiguous.
- Ch1 or Ch4 must be selected as logical channel 0.