CDC ACM

CDC ACM

 

USB CDC (Communications Device Class) ACM (Abstract Control Model) is a vendor-independent publicly documented protocol that can be used for emulating serial ports over USB.

CDC ACM is used to access the U-boot bootloader prompt over USB (see: U-boot#Using_usbtty_from_Linux).

Contents

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• 1 Hardware specifics
  • 1.1 Neo1973 and CDC ACM
  • 1.2 Host PC and CDC ACM
    • 1.2.1 Linux
    • 1.2.2 Windows
    • 1.2.3 MacOS X
  • 1.3 Specification

Hardware specifics

Neo1973 and CDC ACM

The Neo1973 u-boot boot loader contains support for obtaining the boot loader prompt over USB CDC ACM.

The Openmoko kernel also contains CDC ACM device support, contained in the g_serial.ko kernel module.

Host PC and CDC ACM

Linux

Linux has a generic CDC ACM host-side implementation in the kernel module cdc_acm.ko

On 2.6.25 this is at "Device Drivers -> USB support (USB_SUPPORT [=y]) -> Support for Host-side USB (USB [=m]) -> USB Modem (CDC ACM) support (USB_ACM)"

Windows

FIXME

MacOS X

See the USB Serial section in the MacOS X article.