I am debugging s3c2410's usb device driver for linux, I have connect the VCC, GND, D+, D- and the usb device end can detect the insert/plug of usb cable. I installed a IRQ handler for the usb device and it can recieve some interrupt of reset when I insert the USB to host.
But after the reset, no further interrupt happen. Even in the host side there are nothing displayed. I want to know how can I debug it?
According the USB spec, after the HOST hub send Reset to device, the device need to pull up/down a data line to indicate the existence of the device, can I measure this signal on the four lines? Which line should I measure?
I think the host didn't begin to enumerate the device because the device didn't send ACK of the reset to indicate the attach.