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AM3356- USB OTG mode

Naveen M94353
Prodigy 90 points

How we detect HOST and DEVICE in the OTG mode of USB.

  • 0
    TI__Guru 64525 points

    A dual-role USB OTG product must use a micro-AB receptacle.  The ID pin of the micro-AB receptacle should be connected to the respective AM335x ID terminal.

    The USB specification requires the ID pin of a micro-A plug to be ground.  So the AM335x ID terminal will be connected to ground when a micro-A plug is inserted into the micro-AB receptacle.

     The USB specification requires the ID pin of a micro-B plug to be open-circuit.  So the AM335x ID terminal will be open-circuit when a micro-B plug is inserted into the micro-AB receptacle.

    The AM335x USB OTG port will operate as USB host when the ID terminal is connected to ground and operate as USB device when the ID terminal is open-circuit.

    Therefore, the initial mode of operation is determined by the cable attached to micro-AB receptacle.  The mode of operation may be reversed later if connected to another dual-role USB OTG product by using the in-band Host Negotiation Protocol (HNP) to request role change.

    Regards,
    Paul