1.8.7.3 Loopback Modes

Loopback modes perform the following types of loopback tests:

  • EQ-Near End Loopback: Serialized data from PMA is looped from Tx to Rx internally before the transmit buffer. This is called near-end serial loopback. EQ-Near End loopback supports data transmission rates of up to 10.315 Gbps.
  • EQ-Far End Loopback: Serialized data from Rx is looped back to Tx in PMA. This is called far-end serial loopback. EQ-Far End loopback supports data transmission rates of up to 1.25 Gbps.
  • CDR-Far End Loopback: De-serialized data from PCS Rx channel is looped back to Tx.
  • No Loopback: Data is not looped internally.

To select Loopback mode, perform the following steps:

  1. Select LANE in the left pane.
  2. Select Loopback Mode and click on Apply to apply the loopback.
  3. Go to SmartBERT tab, select LANE and choose any prbs pattern and click Start.
  4. Check the status of TX PLL, RX PLL, Lock to Data.
  5. Click Stop to stop the pattern transmission for the selected lane.
Figure 1-40. Debug TRANSCEIVER—Loopback Modes