CSC/ACM:----就是一个协议,通过这个协议,可以用usb设备模拟串口。
USB CDC (Communications Device Class)
ACM(Abstract Control Model) is a vendor-independent publicly documentedprotocol that can be used for emulating serial ports over USB
support:
device drivers------->
[*]usb support------>
<*>usb modem(cdc/acm) support
gadget support
serial gadget