CYUSB3KIT-001 EZ-USB FX3 Development Kit Guide, Doc. #: 001-70237 Rev. *C
85
A.8
USB3.0 Enumeration
Problem
Possible Cause
Possible Solution
FX3 enumerates as a USB
2.0 device even though it
boots firmware that enables
USB 3.0
Applicable only to NEC host
controllers - Excessive spread
spectrum reference clock from
motherboard chipset.
(The NEC host controller does
not have its own reference
clock for USB 3.0. If the
motherboard has an out-of-
spec PCIe reference clock
(either incorrect frequency or
excessive spread spectrum),
the device attached to the USB
3.0 controller will not be able to
track the signal and will fail to
enumerate on the system.)
Check the Spread Spectrum setting in the PC
BIOS. If enabled, disable Spread Spectrum
manually
Incorrect firmware
configuration
Verify that the FX3 firmware has
CyU3PConnectState
set to CyTrue. This
enables USB PHY on the FX3 device and
connects to the USB host. The
CyU3PGetConnectState API returns CyTrue if
the FX3 device is connected and VBUS is
detected by FX3. Also, the
CyU3PUsbGetSpeed API provides
information on the connection speed. See the
FX3 API Guide for details
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