6.3.7. The LPBK Tab
The LPBK tab allows you to perform on-board loopback tests.
The following sections describe controls on the LPBK tab.
- PLL Lock: Shows the PLL locked or unlocked state.
- Pattern Sync: Shows the pattern synced or not synced state. The pattern is considered synced when the start of the data sequence is detected.
- Details: Shows the PLL lock and pattern status:
Allows you to specify which interface to test. The following port tests are available: LPBKx6
- Serial Loopback: Routes signals between the transmitter and the receiver.
- VOD: Specifies the voltage output differential of the transmitter buffer.
- Pre-emphasis tap:
- 1st pre: Specifies the amount of pre-emphasis on the pre-tap of the transmitter buffer.
- 2nd pre (L-Tile): Specifies the amount of pre-emphasis on the second pre-tap of the transmitter buffer.
- 1st post: Specifies the amount of pre-emphasis on the first post tap of the transmitter buffer.
- 2nd post (L-Tile): Specifies the amount of pre-emphasis on the second post-tap of the transmitter buffer.
- Equalizer: Specifies the AC gain setting for the receiver equalizer in four stage mode.
- DC gain: Specifies the DC gain setting for the receiver equalizer in four stage mode.
- VGA: Specifies the VGA gain value.
- PRBS 7: Selects pseudo-random 7-bit sequences.
- PRBS 15: Selects pseudo-random 15-bit sequences.
- PRBS 23: Selects pseudo-random 23-bit sequences.
- PRBS 31: Selects pseudo-random 31-bit sequences.
- HF: Selects highest frequency divide-by-2 data pattern 10101010.
- LF: Selects lowest frequency divide-by-33 data pattern.
- Detected errors: Displays the number of data errors detected in the hardware.
- Inserted errors: Displays the number of errors inserted into the transmit data stream.
- Insert: Inserts a one-word error into the transmit data stream each time you click the button. Insert is enabled only during transaction performance analysis.
- Clear: Resets the Detected errors and Inserted errors counters to zeroes.
TX and RX performance bars: Show the percentage of maximum theoretical data rate that the requested transactions are able to achieve.
Start: This control initiates the loopback tests.
Tx (Mbps) and Rx (Mbps): Show the number of bytes of data analyzed per second.
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