Configuring EP1 as an IN or OUT in EZ-USB® FX2LP™ – KBA90544
Question: Is it possible to configure EP1 as both IN and OUT in FX2LP™?
No, if you configure EP1 as both IN and OUT, the USB host might still enumerate the FX2LP USB device, but you cannot get the device to work (transfer data through the EP1 data endpoints). Data endpoints can only be UNI-DIRECTIONAL. So, if you choose EP1 as an IN endpoint, you have to choose one of the other endpoints (EP2, EP4, EP6, EP8) for the OUT endpoint.