SDAA295 March   2026 DS90LV012A

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2DP/eDP Link Training Procedure and Debugging Methodology
    1. 2.1 Link Training Procedure
    2. 2.2 Debug Guide for Link Training Failure
      1. 2.2.1 Debugging Points when Clock Recovery is Not Successful
      2. 2.2.2 Debugging Points when Channel Equalization is Not Successful
      3. 2.2.3 Debugging Points when Symbol Lock and Inter-Lane Alignment is Not Successful:
  6. 3DP/eDP AUX Channel Signal Overview
    1. 3.1 AUX Transaction Types
    2. 3.2 DPTX and DPRX AUX Design Guidance
      1. 3.2.1 DP/eDP Implementation
      2. 3.2.2 Electrical Specifications
      3. 3.2.3 AUX EYE Diagram
  7. 4Decoding AUX Channel Signal
    1. 4.1 AUX Transaction Syntax
    2. 4.2 How To Use DS90LV011-12AEVM to Capture DP/eDP AUX Channel Signal
    3. 4.3 AUX Channel Decoding Methodology
    4. 4.4 AUX Channel Decoding Example
  8. 5Summary
  9. 6References

4.3 AUX Channel Decoding Methodology

To properly decode AUX channel signals, the hardware must be implemented correctly. More specifically, AUX polarities must be matched between EVM and the AUX channels. With properly matched AUX polarities, each AUX transaction includes both a SYNC END/START and STOP sequence as depicted in Figure 4-3. Conversely, a hardware implementation with swapped AUX polarities does not have a SYNC END/START or STOP sequence as shown in Figure 4-4.

Proper Polarities AUX TransactionFigure 4-3 Proper Polarities AUX Transaction
Swapped Polarities AUX TransactionFigure 4-4 Swapped Polarities AUX Transaction

If AUX polarities are found to be incorrect, swap the AUX+ and AUX- wires on the DS90LV011-12AEVM.

Upon capturing the AUX channel, using a dedicated AUX analyzer extension enables efficient parsing of captured signals. Figure 4-5 shows the AUX waveform decoded by utilizing this AUX analyzer extension, which can be applied to the Logic 2 analyzer.

Logic 2 AUX Waveform Utilizing AUX Analyzer Extension Figure 4-5 Logic 2 AUX Waveform Utilizing AUX Analyzer Extension

When using Logic 2 software, place the AUX analyzer extension in the Logic\resources\windows-x64\Analyzers folder, as shown in Figure 4-6.

AUX Analyzer Extension in Logic 2 SoftwareFigure 4-6 AUX Analyzer Extension in Logic 2 Software

To apply the extension on Logic 2, follow these steps:

  1. Click on Analyzers tab.
  2. Add an analyzer.
  3. Select Display Port AUX.
  4. Set the proper channel to analyze (for example, Channel 00 in Figure 4-7).
  5. Click Save.
Steps to Apply AUX Extension on Logic 2Figure 4-7 Steps to Apply AUX Extension on Logic 2

When using the AUX Analyzer extension, make sure the sampling rate is at least 250MS/s.