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[k20]: USB Attachment By D+/D- Only

Question asked by Hui Shao on Jan 9, 2016
Latest reply on Jan 21, 2016 by Hui_Ma

Hi-

 

My custom board is a CDC host powered by K20D50M. It has to keep powering/charging external USB CDC device through Vbus all the time but only enumerate it when necessary. Both CDC host and device and based on MQX and K20.

 

A common practice for starting enumeration is to plug in USB plug to trigger a transition on Vbus, but my case needs to keep Vbus connected consistently.

 

Question is, is it possible to start the enumeration and USB detachment by only close and open on D+/D- wires by switches?

 

Thanks!

 

Hui

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