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USB Device Mode

KENJI SASAKI
Prodigy 70 points

 

Dear all,

 

We are now developing USB Device Mode driver  on C6A8168.

However, the driver can't detect connection when connected to PC.

The lines D /D- seems to be tri-state.

 

We have two questions.

1. Are data lines not "pulled up/down" when configured as Device Mode ?

2. As shown at the TRM page 2239, a Lock bit to enable access PHYSLEEPn fields is exists. Where is this bit? 

 

Best  regards.

Ken

 

  • 0
    TI__Expert 5475 points

    Hi,

    If our device is operating as a device, then you need to configure USB0/1_MODE register accordingly to properly configure the ID pin as 1. Also you need to tell it that the ID is controlled from the USB0/1_MODE register. To do this you need to set both bits 8 and 7 to '1b'. This will insure that the 15K pull up on the D+ line is enabled when a 5V power on the VBUS is present.

    1. It is the Host responsibility to pull down the D+ and D- lines with 15K Ohms resistors.

    2. I would let others reply to this part of your question. I am currently unable to consult the TRM when replying.

    Best regards, Zegeye

  • 0 in reply to Zegeye Alemu
    TI__Expert 5475 points

    Hi,

    Correction. The pull up on the D+ line when operating as a Device is 1.5K Ohms not 15Kohms. 15Kohms is the pull-down on each data lines that is enabled by the Host.

    Best regards, Zegeye