6 Eye Height Page

The Eye Height Page can assist the user in observing the effects of the redriver EQ settings in their system. The page can be used to display the EyeScan plot of the signal passing through the redriver for each active channel of the connected devices. Further information regarding EyeScan can be found in the Eye Scan with TI PCI-Express Gen5.0 Redrivers, application note. TI recommends the use other lane margining tools to monitor signal quality at each end of the PCIe link to determine best system performance. This tool can be used as a reference and cannot provide best system performance based on EyeScan results alone.

1. Select the desired Scale Per Step as shown in Figure 6-1 for the EyeScan capture. This parameter determines the captured voltage range of the EyeScan operation, providing four options for added granularity if desired. By default, this parameter is set to ±400mV (12.5mV Step).
   
   

   

   
   Figure 6-1 Eye Height Page: Scale Per Step
2. Select the channels for the desired EyeScan capture using the DSx/USx CHx check boxes or the Select All check boxes for each Downstream and Upstream device. These options are highlighted in Figure 6-2.
   
   

   

   
   Figure 6-2 Eye Height Page: Select EyeScan Channels
3. Click the Start Sweep button to begin the EyeScan plot capture. The redriver automatically captures the EyeScan for each selected channel using the programmed redriver EQ settings and displays the result in the Downstream and Upstream plots. The scanning status can be found in the red and green status indicator box on the page, shown in Figure 6-4. Click the Stop Sweep button to cancel the current EyeScan sweep. Please note that clicking the Stop Sweep button ends the capture and plots all channel EyeScan results captured up to the point of cancellation. These buttons are highlighted in Figure 6-3.
   
   

   

   
   Figure 6-3 Eye Height Page: Start Sweep and Stop Sweep
   
   

   

   
   Figure 6-4 Eye Height Page: EyeScan Sweep in Progress
4. After completion of the sweep, the plots display the EyeScan sweep results. An example result plot is shown in Figure 6-5. The Downstream and Upstream plot channel selectors highlighted in Figure 6-6 can be used to emphasize a desired channel on each plot and view the channel's EQ settings. Note that this plot displays the hit counts at varying voltage levels for the selected channels captured directly at the transmitter output pins of the redriver. TI recommends the use other lane margining tools to monitor signal quality at each end of the PCIe link. This tool can be used as a reference and cannot provide best system performance based on this plot alone.
   
   

   

   
   Figure 6-5 Eye Height Page: EyeScan Results
   
   

   

   
   Figure 6-6 Eye Height Page: Plot Channel Selectors
5. To export the selected channel's raw EyeScan data, click the Export Processed Data button highlighted in Figure 6-7. Save the raw data file using the prompted File Explorer.
   
   

   

   
   Figure 6-7 Eye Height Page: Export Processed Data
6. Additionally, the plots can be customized by clicking the plot icon next to each channel. An example customization menu is shown in Figure 6-8.
   
   

   

   
   Figure 6-8 Eye Height Page: Customize Plot