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PC does not recognize the USB serial port after some days

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  • robertferanec
    If you need to turn off board and wait some time to discharge everything, the problem (or one of the problems) what you may have on the board is improper board initialization (e.g. reset, power sequencing, not working crystals, etc ...)

    Notice, they have 4.7k pull up and 10k pull down on reset# signal. In your schematic, you only use 10k pull up - this could be one of the problems you are experiencing (your reset will stay high for some time until board is discharged).

    PS: USB layout is also not ideal, but that would probably cause "only" connecting/disconnecting the device and not freezing it. USB signals are differential pair signals and ideally you would like to be routed them together, without stubs + they should follow 90OHM diff pair impedance (or keep them as short as possible if you use 2 layer PCB)

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  • PC does not recognize the USB serial port after some days

    Hi everyone,

    I developed a board that uses a FT2232D DUAL USB TO SERIAL UART to communicate with a Ubuntu PC.
    The thing is, after some days, for example 1 or 2 weeks, the PC can not recognize the USB Serial Converter. To solve this I need to shutdown all the system for 5 seconds and power on again.
    It is not easy to make debug, because this problem can take 2 days or 2 week to show up.
    I am thinking if the problem could be about my PCB design. I am using 115200 Baudrate.
    Could someone have a look on my schematic and layout?

    Thank you!