Jetson Nano USB3 A-port compliance test problem

[vic.wu]

Hi，
We designed a carrier board for Jetson Nano, which only has one USB3 A-port without using a USB hub. We approached a testing company to test the compliance of the USB port. However, we encountered some issues during the testing and were unable to proceed.

Specifically, we referenced the following two documents during the testing process:

1. Jetson Nano Interface Tuning and Compliance Guide
2. Electrical Compliance Test Specification SuperSpeed Universal Serial Bus

We used a Tektronix DPO72304DX oscilloscope with a bandwidth of 23GHz during the testing. The testing focused on the three items described in document 2: TD.1.1, TD.1.3, and TD.1.4. We used the “devmem2 0x70090420 w 0x10340” command described in document 1 to put Jetson Nano into testing mode.

We were able to successfully test TD.1.1, but during the testing of TD.1.3, it seems that Jetson Nano can only send the waveform of CP0 for a very short period of time before returning to the Rx.Detect state and looping continuously. When we sent the command to switch to the CP1 waveform using a signal generator, Jetson Nano did not switch to the CP1 waveform, and therefore, the testing could not proceed.

The condition of the fixture and the oscilloscope during testing are as shown below.

We hope to receive your assistance and thank you very much.

[mhd0425]

The reference design uses a 560uf capacitor on usb vbus. How about you?

[Trumany]

Hi, have you disabled USB power management?

Issue “echo on > /sys/bus/usb/devices/usbX/power/control” to disable USB power management including ELPG. Jetson Nano Interface Tuning and Compliance Guide has following commands to do that:

#!/bin/sh

for hub in $(ls -d /sys/bus/usb/devices/usb?); do

echo on > $hub/power/control

done

[vic.wu]

The reason was finally found to be this. The personnel in the laboratory did not strictly follow the guided steps during the last test.