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altineller

VBUS detect OR USB disconnection detection

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Hello,

Is there any way to figure out if a Tiva-C board is being powered with the usb connector, or from an external power supply connected to vbus?

This is the problem I am facing: I am poweing Tiva-C board from the vbus connector, on a robot. At times we need to connect the usb cable for programming. Since VBUS is connected to external battery, it will "some times" (most of the time) - crash the computer.

So I am using a pololu switching regulator, with a shutdown control pin. What I would like to do is, the device to figure out if usb power is being used, and shutdown the external power supply.

I did search the web and found out that PD_7 is the vbus detect pin, and just digitalRead on that pin would lead to result, but I tested it, and found out it does not work.

 

Any ideas/help/recommendation is greatly appreciated.

 

 

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There is no connection from VBUS to any of the pins on the chip. What I would recommend is to tap ICDI_VBUS through a resistor divider to end up with 3.3V and then connect that to one of the pins. You might also be able to just directly connect ICDI_VBUS to the switching regulator control pin either through a resistor divider or directly if it is 5 Volt tolerant.

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