PORTS Forum

Ports and Interfaces => USB => Topic started by: ravi.holal on October 10, 2013, 11:51:15 am

Title: usb device is not resetting
Post by: ravi.holal on October 10, 2013, 11:51:15 am

Hi,

I have written a usb host driver which is  vendor specific. I  am sending vendor specific request to device which has to reset the device.
But it is not happening.

Observation: vendor specific request is success

Expected Result:
usb 1-4:  new high speed USB device using ehci_hcd and address 7 
usb 1-4: USB disconnect, address 7         
usb 1-4: new high speed USB device using ehci_hcd and address 8

Actual result:
 usb 1-4: new high speed USB device using ehci_hcd and address 13


Please help me to resolve this

thanks in advance

Title: Re: usb device is not resetting
Post by: Barry Twycross on October 10, 2013, 02:41:49 pm

A device will not automatically fall off the bus if it resets itself.

To fall off the bus and be reenumerated the device has to drop the pull up and then reassert the pull up. Its best to wait a short time between dropping and reassrting the pull up, 500ms is a good time to wait.