how to write usb driver in qnx?

where can I download the sample of usb driver for qnx?I think the source code or technical article is helpful.

this is also my question. please help us!!!

There is a USB Driver DDK, have you tried this? It is for developing USB class drivers of different classes.

I have read the ddk,it contains a lots of function,but there hasn’t sample to tell me how to use it.

What do you mean ‘read’ the DDK? You only have read the docs then. You should download the DDK samples from the ‘myQNX’ Download Center. You’ll find it under ‘Driver Development Kits’.