FX2LP - USB Fails to connect during power-up | Cypress Semiconductor
FX2LP - USB Fails to connect during power-up
We've run into a perplexing problem where our computer which is connected to our instrument via a FX2LP USB intermittently fails to connect. A USB monitor shows the communication exchange and the second set of "Get Configuration Descriptor" commands never get a response. If the USB cable is removed/replugged the device communicates correctly. A restart of the computer from the USB error state also connects correctly. Of course we'd like the instrument to connect correctly the first time.
We observed that Windows 8.1 sometimes does a fast boot and sometimes it does a slow boot. It was only during fast boot that we observed failures. We wrote a service to use DEVCON to programmatically remove and rescan for the USB device. We discovered that this service only ran during slow boot despite being marked as Automatic. Ultimately our solution was to change Power Options in Windows 8.1 and disable Fast Boot.
Has anyone else ran into a similar situation with the USB? What solution did you use?