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USB 2.0 loopback flashing speed LED

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  • USB 2.0 loopback flashing speed LED

    Testing a USB PCIe 4-port card. On 2 cards that have been reported defective, when the USB 2.0 Loopback tester is first connected to one of the 4 USB ports, the tester goes through a self-test/initialization. Normally it finishes with the Red Power LED and Orange Hi-Speed LED are lit solid. On the 2 failed cards, the self-test ends with the Power LED lit solid but the Orange LED flashes at a high rate. Is this symptom indicating where the problem is? John

  • #2
    The Orange LED is expected to stay steadily lit once the USB 2.0 Loopback tester successfully completes its self-test. However, the persistent flashing of the Orange LED indicates the presence of underlying low-level issues that disrupt the enumeration process, resulting in frequent resets initiated by the host. Each time the host triggers a reset, the LED turns off.
    Another, although less likely, possibility is that the tester is entering suspend mode frequently.


    • #3
      I suspected as such. The tester is fine. 3 tester react the same way and work fine on 2 dozen of the same cards. Just 2 PCIe USB cards fail with the flashing orange LED, which were returned from a customer. I appreciate the information.