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TS3USB221 enable cycling

Jamaal_Charles
Genius 3245 points
Other Parts Discussed in Thread: TS3USB221EVM

Hello,

We are evaluating the TS3USB221EVM, and we are finding that we have to cycle the Output Enable to switch from one port to another.  We were hoping not to have to add a GPIO line to control this.  We don't see anything in the datasheet or user guide talking about this.  Is cycling the OE required?

Thanks,

Jamaal

  • 0
    TI__Expert 6395 points

    Hello Jamaal,

    You should not need to cycle the OE.  Are you testing continuity when you switch the ports?

    Regards,

    Andrew

  • 0 in reply to Andrew_Mason
    Genius 3245 points

    Hi Andrew,

    Here is how we are testing the device...We are using two separate flash drives, and we write files onto each separately.  We don't have to remove the drives, but we do have to cycle the OEn pin “after” changing the direction of the switch.  Once we cycle the OEn, without removing the flash drives, they work as expected.  However, we've been trying out a similar Maxim device, and it works without cycling the OE in the same scenario.

    Thanks

  • 0 in reply to Jamaal_Charles
    TI__Expert 6395 points

    Hello Jamaal,

    After you change the direction of the switch can you test continuity between the common side and the newly selected port to be sure the connection is being made?

    Regards,

    Andrew

  • 0 in reply to Andrew_Mason
    Genius 3245 points

    Hi Andrew,

    The physical connection seems to be fine, but we can't make a data connection without cycling the OEn.

    Thanks

  • 0 in reply to Jamaal_Charles
    TI__Expert 6395 points

    Hello Jamaal,

    I performed the following test with the TS3USB221EVM and recorded my observations:

    1. Connect common side of EVM to PC.
    2. Plug a USB flash drive into one of the two USB port on the other side of the EVM
      1. I see the USB driver install and I can edit files on the drive
    3. Plug a Mouse into the other USB port
      1. No change
    4. Change the Sel switch on the EVM to the other position
      1. USB thumb drive is lost in "My Computer" and I can now use the mouse that was attached to the other port

    Can you repeat this same procedure with the flash drives and tell me your results?

    Regards,

    Andrew

  • 0 in reply to Andrew_Mason
    Genius 3245 points

    Thanks Andrew,

    We actually just resolved this issue. It was not the TI device.  The same control line was attached to some LED circuitry, and the GPIO line was too heavily loaded down to work properly.  We've changed that, and everything works great.

    Sorry

  • 0 in reply to Jamaal_Charles
    TI__Expert 6395 points

    Hello Jamaal,

    Excellent!  Let me know if you have any further questions on the device that I can assist with.

    Regards,

    Andrew