USB_OTG1_VBUS pin connection (USB_OTG1 is a diagnostics port) between Charging connector and IMX7

[logeshs]

Hi ,

In MCIMX7D7DVK10SC, in USB_OTG1 is used for diagnostics purpose connected to microUSB connector. We are going to use the same USB connector for charging our wearable device. Shall we connect the USB_OTG1_VBUS pin to VBUS pin of USB connector or shall we leave it floating?

In other words, are we still able to use USB_OTG1 to access IMX7 for diagnostics purpose even if we left VBUS of IMX7 floating? (i.e, connecting only DP and DN from USB charging connector to USB_OTG1 port of IMX7)

Thanks & Regards,

Logesh

[gusarambula]

Hello Logesh,

If you will be using USB OTG as in your case, you should have some circuitry that makes sure that the USB_OTGn_VBUS power supply is not provided at power on and that it can switch depending on the USB mode. This is mentioned in table 12 of the Hardware Development Guide for i.MX7 (link below)

https://www.nxp.com/docs/en/user-guide/IMX7DSHDG.pdf

The reason why VBUS has to be turned on and off is that depending on the more in which it is working (host or device) it’s voltage would be provided to the device (host mode) or be received from the host (device mode).

I hope this information helps!

Regards,

[infanneraysh]

Hi, 

We are working on the same team. Sorry for the confusion. We are not using USB OTG function. We are just planning to use our system only as device.

From USB connector, DP & DN is routed to IMX USB_OTG controller. In this case do we need to do any connectivity for vbus pin of the IMX7 or can we leave it floating. Please suggest. 

[gusarambula]

Hello Infan Neraysh,

If you will be using only as a device then the VBUS voltage will be provided by the host so you may leave the VBUS pins floating.

I hope this information helps,

Regards,

[gusarambula]

Hello infanneraysh,

I'd like to elaborate a little more. You wouldn't leave the VBUS floating per se. You would route it to the VBUS signal on the USB port so the host can provide power. Alternatively, you may provide VBUS directly and just leave the VBUS from the connector floating to work as a self-powered device.

I hope this answer your question!

Regards,

[logeshs]

Hi,

Kindly update me.

Thanks