6.3.6. The PCIe Tab
This tab allows you to run a PCIe* loopback test on your board. You can also load the design and use an oscilloscope to measure an eye diagram of the PCIe* transmit signals.
Figure 25. The PCIe Tab
The following sections describe the controls on the PCIe* tab.
Displays the following status information during a loopback test:
- 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 sync status:
PCIe* x16 Gen3
Allows you to make changes to the PMA parameters that affect the active transceiver interface. The following settings are available for analysis:
- 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: 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: 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.
- All PMA settings should be changed as given in the figure below:
Figure 26. PMA Settings
Specifies the type of data contained in the transactions. The following data types are available for analysis:
- 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.
Displays data errors detected during analysis and allows you to insert errors:
- 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 error: Inserts a one-word error into the transmit data stream each time you click the button. Insert error is only enabled during transaction performance analysis.
- Clear: Resets the detected errors and inserted errors counters to zeroes.
- Start: Initiates the selected ports transaction performance analysis.
Note: Always click Clear before Start
- Stop: Terminates transaction performance analysis.
- TX and RX performance bars: Show the percentage of maximum theoretical data rate that the requested transactions are able to achieve.
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