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BF525 USB Vbus error

Question asked by PraveenP on Jun 9, 2010
Latest reply on Jun 28, 2010 by CraigG

Hi I am using bf525 for a multimedia project.

Using USB OTG module for playback from USB devices.

I am facing problem with USB stick detection.

 

When the usb peripheral is conntected and i turn on my system, the USB is detected and enumeration is successful.

But when I insert a USB device in a hot plug manner, I see Vbus interrupt.

 

To avoid any initial surge, there is a 110uf capacitor near the connector for vbus.

When I look at the Vbus bits in OTG_CTR MMR, it shows as "0x98" it means vbus valid. isnt it? If i ignore that interrupt, i dont get any more connection interrupts.

 

Also, I see that the threshold for detecting Vbus valid is 4.75V(OTG spec). But i dont see any dip in vbus voltage. How does BF525 knows the 4.75v threshold(i mean is there any voltage divider internally)?

 

Thanks PraveenP

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