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Ixiasoft
7.1. Internal Serial Loopback Mode
The Interlaken IP core supports an internal TX to RX serial loopback mode.
To turn on internal serial loopback in L- and H-tile device variations:
- Reset the IP core by asserting and then deasserting the active low reset_n signal.
- After reset completes, set the value of bits [NUM_LANES-1:0] of the LOOPBACK register at offset 0x12 to all ones.
Note: Refer to IP Core Reset for information about the required wait period for register access.
- Monitor the RX lanes aligned bit (bit 1) of the ALIGN register at offset 0x20 or the rx_lanes_aligned output signal. After the RX lanes are aligned, the IP core is in internal serial loopback mode.
To turn off internal serial loopback:
- Reset the IP core by asserting and then deasserting the active low reset_n signal. Resetting the IP core sets the value of bits [NUM_LANES-1:0] of the LOOPBACK register at offset 0x12 to all zeros.
- Monitor the RX lanes aligned bit (bit 0) of the ALIGN register at offset 0x20 or the rx_lanes_aligned output signal. After the RX lanes are aligned, the IP core is in normal operational mode.
To turn on internal serial loopback in E-tile device variations:
- Reconfigure the PMA settings by using PMA attribute code 0x0008 of the transceiver PHY reconfiguration interface.
- Write 0x84[7:0] = 0x01
- Write 0x85[7:0] =0x01
- Write 0x86[7:0] = 0x08
- Write 0x87[7:0] = 0x00
- Write 0x90[0] = 1’b1
- Read 0x8A[7]. It should be 1
- Read 0x8B[0] until it changes to 0
- Write 0x8A[7] to 1'b1 to clear the 0x8A[7] value
- Perform the initial RX equalizer adaption calibration steps. Refer to the PMA Receiver Equalization Adaption Usage Model section in the E-Tile Transceiver PHY User Guide.
- Reset the IP core by asserting and then deasserting the active low reset_n signal.
- Monitor the RX lanes aligned bit (bit 1) of the ALIGN register at offset 0x20 or the rx_lanes_aligned output signal. After the RX lanes are aligned, the IP core is in internal serial loopback mode.
To turn off internal serial loopback:
- Monitor the RX lanes aligned bit (bit 0) of the ALIGN register at offset 0x20 or the rx_lanes_aligned output signal. After the RX lanes are aligned, the IP core is in normal operational mode.
- Reconfigure the PMA settings to turn off the serial loop back mode by using PMA attribute code 0x0008 of the transceiver PHY reconfiguration interface..
- Write 0x84[7:0] = 0x00
- Write 0x85[7:0] =0x00
- Write 0x86[7:0] = 0x08
- Write 0x87[7:0] = 0x00
- Write 0x90[0] = 1’b1
- Read 0x8A[7]. It should be 1
- Read 0x8B[0] until it changes to 0
- Write 0x8A[7] to 1'b1 to clear the 0x8A[7] value