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FT2232H USB Device not responding

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  • FT2232H USB Device not responding

    I've designed a PCB which contains FT2232H for UART and SWD debugging for a microcontroller in the PCB (STM32L0). The FT2232H circuit looks like this:

    https://i.stack.imgur.com/aPKno.png​

    and the power schematic that contains the USB micro connector looks like this:

    https://i.stack.imgur.com/v1xPe.png​
    When I connecting the board to the USB port in my PC all the 3 LEDs (D3, D4, D5) are light up, it means that the power rails are OK (VBUS - 5V, 3.3, 3V) but, then I don't see any message from windows about new USB device detection. nothing happens. the system doesn't detect device insertion or removal. I have designed the FT2232H circuit above according to the datasheet(page 69 Bus-Powered Configuration), and this reference design
    Do you have any suggestions on how to debug or to solve my problem?
    Thank you very much!

  • #2
    Lot of settings on this puppy... check you settings on what type of pin functions you have..

    also Did measure your voltages on the chip with a multimeter? just to be sure.l. the led might light up but that doe snot mean the chips get power..



    btw why the 3V0 psu? not used or used somewhere else..

    Comment


    • barakg
      barakg commented
      Editing a comment
      I did measure my voltages on the chip with a multimeter and everything is ok!

      the 3V0 psu is dedicated for LCD module.

  • #3
    Have you installed drivers for the chip in Windows?

    Comment


    • barakg
      barakg commented
      Editing a comment
      Yes, I did. But it doesn't matter. still, Windows should be able to detect new USB composite device and it doesn't
      Last edited by barakg; 02-06-2019, 09:29 AM.

  • #4
    Are you sure USB negative and positive signals are not swapped? Double check footprint and connector. Also, try different cables - maybe a short one.

    Comment


    • barakg
      barakg commented
      Editing a comment
      Hello sir, I have double checked footprint and connector before sending the PCB files for manufacture. also, I have tried different USB cables, PCs and different OS (Linux). I have also verified physically the footprint and USB connector when the PCB arrived. I'm kind of helpless.
      Last edited by barakg; 02-06-2019, 01:30 PM.

  • #5
    Is you crystal running? do you have an osciloscope to double check?

    Is the FTDI put on correclty on the board.. (not rotated or something)


    Comment


    • barakg
      barakg commented
      Editing a comment
      I don't have an oscilloscope. can you suggest me another tool to verify it? is it possible with another tool?
      the FTDI IC put on the PCB correctly.

  • #6
    Only thing I see is missing pullup on EECS/EECLK, EEPROM should be blank or not present at this point. so that's probably OK.

    If the USB connector landpattern had pins numbered backwards then we would not have correct power polarity

    the reset circuit on the reference board has a pulldown and pull up on reset - probably to handle what happens when you un-insert the board and then re-insert before the caps discharge.
    You might try adding that to be sure you start up when there is some residual voltage in the caps (IE R2 in ref schematic)

    and, That leaves the crystal or some open/short in the assembly.

    A hi-res closeup photo of the board from under the smt microscope (from both sides) and oscillator scopeshot would help




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