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TUSB2036: Not reporting to host

Bruno Inuggi
Prodigy 40 points
Part Number: TUSB2036

Hello there,

I've made a bus powered 3-port USB hub and there's no way I can get it to show up on my computer (which has perfectly working USB ports).

I'm using a USB analyzer tool on Windows to check the packets being sent and received, and see absolutely nothing when I plug in the USB hub. I checked the 5V and 3.3V rails, and those are good. I tried forcing some of the pins low or high (bypassing the pulls) to see if that made the chip wake up (/BUSPWR, /RESET, MODE) but to no avail. I also used an oscilloscope to check the 6MHz waveform and that looks fine as well.

Is there something wrong with my design (pdf attached)?

Some notes:

  • The DP0PUR resistors is 1.1k (don't have 1.5k available), is that value critical?
  • I know there are no 15k pull downs on the devices' side but I soldered them anyway on the board afterwards.
  • Being the first prototype, there's no ESD or overcurrent protection.

Thank you,

Bruno

0743.USB-HUB.pdf

  • 0
    TI__Guru 60870 points

    Hi Bruno,

    A regular USB 2.0 port that supports high speed should not need the external 15K pulldowns.  External pulldowns are typically only required for full speed hosts / hubs / devices.

    Also, there should be a capacitor to ground on the reset, so that the hub gets a power on reset before it is pulled high by the pullup.  

    Can you check the line states on DP/DM?

    Regards,

    JMMN

  • 0 in reply to JMMN
    Prodigy 40 points

    Hi !

    Thanks for the heads up on the capacitor (100nF), although I added it externally and nothing changed. The states of the upstream lines are (when plugged into my PC and no packets are detected on the anlyzer):

    - DM: 0V

    - DP: ~3.15V

  • 0 in reply to Bruno Inuggi
    TI__Guru 60870 points

    Can you install usbview.exe or usb device tree viewer and see if anything shows up when you connect the TUSB2036?  The host should report something if DP is pulled high even if nothing else happens.

    Regards,

    JMMN

  • 0 in reply to JMMN
    Prodigy 40 points

    I installed usbview.exe and when I plug it in, nothing changes on the tree viewer.

    I also realized that this being a full speed hub, it might not work for our use case so I will be moving away from it anyway.

  • 0 in reply to Bruno Inuggi
    TI__Guru 60870 points

    Understood.  If you decide to continue with the Full Speed hub design, try adjusting the R1 value and also confirming if the SUSPEND pin goes high when the hub is connected.

    Regards.

    JMMN