SDAA519 September   2026 DRA821U-Q1 , TDA4AEN-Q1 , TDA4AH-Q1 , TDA4AL-Q1 , TDA4AP-Q1 , TDA4APE-Q1 , TDA4VE-Q1 , TDA4VEN-Q1 , TDA4VH-Q1 , TDA4VL-Q1 , TDA4VP-Q1 , TDA4VPE-Q1

 

  1.   1
  2.    Abstract
  3.    Trademarks
  4. 1  Introduction
  5. 2  Acronyms and Definitions
  6. 3  USB 2.0 High Speed TX Compliance: Theory of Operation
    1. 3.1 USB 2.0 High Speed Signaling Overview
    2. 3.2 xHCI Port Test Control and Compliance Mode Entry
    3. 3.3 Eye Diagram Compliance
  7. 4  Register Reference
    1. 4.1 xHCI PORTSC — Port Status and Control Register
    2. 4.2 PORTPMSC Bit-Field Description (USB 2.0 — xHCI Spec)
    3. 4.3 Compliance Write Value Decode: 0x40000000
    4. 4.4 USB2 PHY TX Amplitude Register — USB2SS_PHY2_AFE_TX_REG1
  8. 5 Compliance Procedure: TDA4VEN / J722S / TDA4AEN
    1. 5.1 Hardware Requirements
    2. 5.2 Software Requirements
    3. 5.3 Hardware Setup
    4. 5.4 Physical Connections
    5. 5.5 Device Tree Source (DTS) Modification for USB0
    6. 5.6 Step 1: Verify EVM Boot and Console
    7. 5.7 Step 2: Write xHCI Registers to Enable HS Test Packet Mode
    8. 5.8 Step 3: Capture the HS Test Packet Waveform on the Oscilloscope
  9. 6 USB-IF Electrical Analysis Tool: Post-Processing Procedure
  10. 7  Adjusting the HS TX Amplitude
    1. 7.1 TX Amplitude Adjustment Procedure
  11. 8 Compliance Procedure: J7200/J784S4/J721S2/J742S2
  12. 9 Troubleshooting
  13. 10Summary
  14. 11References

9 Troubleshooting

Table 9-1 Troubleshooting Guide
Symptom Likely Cause Corrective Action
No signal on oscilloscope after register writes Register writes did not take effect; incorrect port selected; USB0 not enabled in DTS Verify DTS has USB0 enabled. Check that no USB device is connected to the port. Re-issue all three devmem2 writes in sequence.
Eye diagram clips inner mask (amplitude too low) Default BOOST setting too low; USB mux or Type-C IC in signal path Use short SMA cables. Increase BOOST via 0x0F908004 register write.
Eye diagram exceeds outer mask (amplitude too high) BOOST value set too high; Decrease BOOST value through register write.
USB-IF tool reports rise and fall time failure Excessive parasitic capacitance on D+/D− traces; cable or connector discontinuity Inspect SMA cable integrity. Verify matched SMA cable pair. De-skew the scope channels. Check the test fixture connection.
Serial console not responding after power-on Wrong COM port selected; baud rate mismatch For TDA4VEN, use the third COM port of the four available. Set baud to 115200.
HSNE test fails but HSFE test passes Captive cable in signal path Confirm no captive cable. Select HSNE. If captive cable is present, select HSFE.