View Full Version : USB WDM driver and Canon camera problems

March 10, 2010, 16:03:19

It seems that when I use my DFK31AU03.AS as a guide camera in PHD guiding, as long as I do not have my Canon 350D camera USB cable attached and the camera on, things run fine. But as soon as I turn on the camera and the camera USB cable is connected to the laptop, PHD freezes. Is there any known issues between the IC WDM UVCCAM driver and Canon drivers? Would eliminating the IC driver and running ASCOM drivers only for the DFK31AU03.AS be a possible workaround?

Stefan Geissler
March 15, 2010, 10:12:58

I am afraid, it is not a problem of the drivers, but of the USB hardware. If there are many devices connected to one USB controller, all of these devices start to send packages. The UVC (USB Video Capture) devices send image data too. If their data stream is interrupted by another device, then a data block is missing and the image in incomplete. The data block can not be sent again, it is lost. Thus the driver drops the images. This is, what you see. You may slow down the frame rates to avoid this problem. Better is to connect both cameras to different USB controllers.