Custom board USB tuning

Autonomous Machines Jetson & Embedded Systems Jetson Xavier NX
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I have custom board for the NX nano, for its USB0 port (recovery) I added a NUF2042XV6T1G device for the electrical protection stage. For some reason, the port doesn’t work, and its seems like signal integrity issue.
for that reason I can’t recover/flash my jetson from my board, and need to remove it to some dev kit.
(trying to) follow the ‘Jetson Xavier NX Tuning and Compliance Guide’ I couldn’t understand many things:

  1. if I will succeed to re-tune the port. How it fused to the jetson? if the jetson is on recovery mode, does this tuning will be saved?
  2. is there proper tool to change the registers? or I must use some raw tool, such like devmem2, and to do the bit manipulation by my self?
  3. do I must do the ‘USB 2.0 Test Mode Programming Sequence’ chapter before changing registers (for example the HS_SQUELCH)?

My assumption is that because the NUF has Rs of 22ohm, its a ‘relevant’ resistance. and might break one of the thresholds of USB compliance that I got from here USB High Speed Chirp Explained.
The line that break is: D+ Voltage is about 140mV instead of 100mV

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1 Like
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For USB2.0, the guide has provided the procedure of tuning, the tool can be devmem2, please read and follow that. For USBSS, the tuning of USBSS is not supported as the custom design is assumed to follow the Design Guide well and should not have signal integrity issue.

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Thanks for the replay. I followed to guide.
The guide doesn’t say, or not clear about some things. for example:

  1. if I will succeed to re-tune the port. How it fused to the jetson? if the jetson is on recovery mode, does this tuning will be saved?
  2. do I must do the ‘USB 2.0 Test Mode Programming Sequence’ chapter before changing registers (for example the HS_SQUELCH)?
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No fuse needed, the registers value should be written to SW as said in guide.

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so, after boot. if the usb is on recovery mode. how the tuning should be loaded? my SW doesn’t run at this point

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No need to tune for Recovery mode as the port is running at not so high data rate.

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Ok, so the tuning is for Hi-Speed only?

  • USB 1.0/Low-Speed: 1.5 Megabits per second (Mbps)
  • USB 1.1/Full-Speed: 12 Mbps.
  • USB 2.0/Hi-Speed: 480 Mbps.
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Customer has no need to care about recovery mode USB part, it is in default setting which won’t be changed.

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Thanks, I will re evaluate the board, and why the USB doesn’t works. so far the calibration were my only guess

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