USB - Controller Peripheral Mode

Hi Team,

Can you please take a look on the above question?

BR,

Eran

I haven’t implemented resume detection external to the USB PHY, but it doesn’t look too difficult.  The USB resume signaling (K-state) for a full speed device is a differential 0 (switching from idle which is J-state).  That is, D- goes from low (in J state) to high (in K state), while D+ goes from high (in J state) to low (in K state).  So if you connect D+ or D- to another GPIO input on Freon you can detect resume signaling with a rising edge interrupt (on D-) or a falling edge interrupt (on D+).  The USB D+/D- lines are referenced to 3.3V so the GPIO must also be referenced to 3.3V or connected through a level shifter.

Eran Hershber said:

In the TRM. section 35.2.7.1 (controller peripheral mode), it's mentioned:

Entry into suspend mode - When operating as a peripheral device, the controller monitors activity on the bus and when no activity has occurred for 3 ms, it goes into Suspend mode. If the Suspend interrupt has been enabled, an interrupt will be generated at this time. At this point, the controller can then be left active (and hence able to detect when Resume signaling occurs on the USB), or the application may arrange to disable the controller by stopping its clock. However, the controller will not then be able to detect Resume signaling on the USB. As a result, some external hardware will be needed to detect Resume. 

The question is - Does TI have any recommendations for external hardware compatible with USB standard that can be added to detect Resume if the PHY is in low power mode?