xCORE-200 USB & VBUS - best practice?

Technical discussions around xCORE processors (e.g. General Purpose (L/G), xCORE-USB, xCORE-Analog, xCORE-XA).
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xCORE-200 USB & VBUS - best practice?

Postby expertsleepers » Fri Nov 04, 2016 1:26 pm

Could someone please advise best practice for the USB & particularly VBUS connections on xCORE-200 processors?

I've seen elsewhere that VBUS should be connected even for USB devices.

The reference design has no ESD or other protection on the USB inputs, which seems a little remiss. If someone could recommend a bullet-proof protection scheme for a self-powered USB device I'd be grateful.
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Postby mon2 » Fri Nov 04, 2016 2:00 pm

Please review the possible issues (raised in this user forum) you may face if you do not use Vbus for your pending project. Varying with your USB widget design, you risk having the end product not being enumerated after the host PC enters and then wakes from a sleep cycle. At least one offshore manufacturer using XMOS processors is guilty of this practice. Only a cold reset of the PC and widget allows for the proper enumeration when self-powered. This was for an audio device based on the XMOS processor but the firmware for the project was developed to operate from USB Vbus.

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