Part Number:AM1808
This is a mature product of customer, Recently they sell it to oversea customer, the end customer report sometimes the USB connected scanner doesn't work, field check found the USB0_DRVVBUS is LOW, so no 5V on USB0_VBUS, then the connected scanner doesn't work.
The end customer bought 50 set equipment, most of them report such issue from time to time.
The usually use case is connecting the USB scanner, finish some job, put it aside or move to next room to charge the battery without power off the machine, when use it again, the scanner doesn't work, but other feature is normally, the AM1808 is running, if power cycle the machine/AM1808, it resume. Seems the USB0 module hanged.
The USB0_ID is pulled down to GND with 0ohm resistor.
Question: What condition will result in such issue? as it is not reproduced in customer lab yet, What kind of information can help to debug the issue? if needed customer will try to capture more detail information including log, register value etc please give some clue.
Customer did some experiments in lab try to reproduce the issue, but did not reproduce.
#1. After power up the works, decrease USB0_VBUS < 4.4V, USB0_DRVVBUSn output did not change, still is high.
#2. Keep USB0_VBUS<4.4V during power up, USB_DRVVBUS is high.