Цитата(Genadi Zawidowski @ Jun 6 2017, 20:55)

Ftdl переходник ни разу не CDC, о чем вам любезно лог и сообщает.
Для тестирования можете на любой плате от st поднять CDC и посмотреть на результат енумерации.
Вот на плате "поднят" CDC:
USB Device Attached
PID: 3h
VID: 10c4h
Address (#1) assigned.
Manufacturer : Silicon Laboratories Inc.
Product : EFM32 USB CDC serial port device
Serial Number : N/A
Enumeration done.
This device has only 1 configuration.
Default configuration set.
DEBUG : Cannot Find the interface for Communication Interface Class.
Device not supporting CDC class.
Вывод несколько иной, но суть та-же - не работает....
А вот, например. подключение флешки:
USB Device Attached
PID: 3e00h
VID: 13feh
Address (#1) assigned.
Manufacturer : UFD 2.0
Product : Silicon-Power16G
Serial Number : 12020813017E6C214004E780086
Enumeration done.
This device has only 1 configuration.
Default configuration set.
Switching to Interface (#0)
Class : 8h
SubClass : 6h
Protocol : 50h
MSC class started.
Number of supported LUN: 1
LUN #0:
Inquiry Vendor : UFD 2.0
Inquiry Product : Silicon-Power16G
Inquiry Version : PMAP
MSC Device ready
MSC Device capacity : 2619997696 Bytes
Block number : 30283007
Block Size : 512