USB Driver Problem

[heav...@gmail.com]

I develop a Samsung S3C2440 platform. The USB is a serial class
function. I plug the platform to a host PC via USB cable. The PC
detect the USB serial class funtion and work well. When I unplug the
USB cable, the PC know the platform is removed. But I find the
platform does not know it is removed for host PC. I check the debug
message, nothing output when unplugging USB cable. It seems no event
occurs. Do I need to set a GPIO as INT to let platform kown USB cable
is removed or what settings I need to do?

[David Liao (MS)]

When device detached from Host, it only lost VBUS(5 Volt) signal from host.
If your device does not have a way to detect the VBUS removal, you probably
do have a good way to detect the detach.

But, I think this is OK. When device re-attached to the bus. Host will issue
USB Reset on the bus. When USB Function controller receives Reset, it can
assume that the Bus is be detached and re-attached again.

So, if you don't have good way to detect the VBUS, you can send out faked
Detach and Attach event when USB Function controller receives Reset Event. A
lot of Microsoft USB Function Controller code does this.

David Liao

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