I have a question about what error density to expect from USB. We have made an USB 1.1. device 12 Mbit/s and we encounter transmission errors. The PC OS is Win2000, Host Controller is Intel(r) 82801AA USB Universal Host Controller. Single or double bit errors occur after some 1 - 20 Mbytes transferred, despite the USB 16-bit CRC. We never succeed in transferring 40 Mbytes without an error. If the average fault occurs after 10 Mbytes, then we have a fault density per bit transferred of 1/(10e6*8) = 1.25e-8. Is this normal and to be expected? Cable length is 2 meters.

Best Regards
Tomas Carlström