PROCESSOR-SDK-AM64X: USB0_ID Floating pin

Hello Thierry HAUSER

Thank you for the query.

Please refer to the below TRM section and let me know if this helps.

12.2.4.2.2 USB Subsystem Application
As the USB controller modules present in this device are DRD (Dual-Role Devices), they can support operation as either a USB Host or a USB Device. The operational mode determination is made based on the state of the USBn_ID pin; when this pin is grounded, the controller will operate as a USB Host, when this pin is left floating, the controller assumes the role of a USB Device. For implementations that do not require DRD functionality, the USBn_ID pin can either be left floating or can be grounded in the board design depending on the static role required. For implementations that do require DRD functionality, the USBn_ID pin should be connected directly to the corresponding ID pin on a USB Micro-AB socket. In doing so, the USBn_ID pin will be correctly terminated (open or grounded) depending on the cable attached and the controller will enter Host or Device mode accordingly.

Regards,

Sreenivasa

Thanks Kallikuppa for your answer,

Is it possible to have an electronic diagram of this pin interface (current generator and voltage sense) in order to have a better confidence into a floating net in term of EMC immunity?

Thanks for your reply.

Thanks Kallikuppa for your answer,

Is it possible to have an electronic diagram of this pin interface (current generator and voltage sense) in order to have a better confidence into a floating net in term of EMC immunity?

Thanks for your reply.

Hello Thierry HAUSER

Thank you for the inputs.

I see 2 similar messages. I assume you did not want to add anything additional.

Thierry HAUSER said:

Is it possible to have an electronic diagram of this pin interface (current generator and voltage sense) in order to have a better confidence into a floating net in term of EMC immunity?

Can you please elaborate the requirement.

What is the device configuration in your system?

Regards,

Sreenivasa

Hello Thierry HAUSER

I have captured the offline discussion below

Customer input 

Yes we would like to  implement Dual Role function with micro AB connector in order to support OTG feature.

USB_ID pin will be connected to micro AB connector. So when no cable connected or in case of USB device role, this pin will be floating.

How to ensure that AM64xx electronic pin manage EMC immunity on such floating net? (how strong is internal current generator).

TI reply 

You should only connect the ID pin to VSS or leave it open.  There is an internal current source that gets turned on when the controller need to determine the resistance of the ID signal to ground.  The voltage developed across the ID resistor is measured only when the current source is turned on.  The internal resistance measuring circuit is designed to be compliant to the industry standard ID resistor values defined in the USB specification.  Connecting any resistance other than the recommendation may produce unexpected results.

Regards,

Sreenivasa