Fixed incorrect interface values in the VirtualSerialMouse and KeyboardMouse demo class driver structures.

Added caveat information to the CDC device class driver.

1 files changed, 17 insertions, 0 deletions

diff --git a/LUFA/Drivers/USB/Class/Device/CDC.h b/LUFA/Drivers/USB/Class/Device/CDC.h
index 617410b11..d248868cd 100644
--- a/LUFA/Drivers/USB/Class/Device/CDC.h
+++ b/LUFA/Drivers/USB/Class/Device/CDC.h
@@ -38,6 +38,23 @@
  *  \section Module Description

  *  Device Mode USB Class driver framework interface, for the CDC USB Class driver.

  *

+ *  \note There are several major drawbacks to the CDC-ACM standard USB class, however

+ *        it is very standardized and thus usually available as a built-in driver on

+ *        most platforms, and so is a better choice than a proprietary serial class.

+ *        

+ *        One major issue with CDC-ACM is that it requires two Interface descriptors,

+ *        which will upset most hosts when part of a multi-function "Composite" USB

+ *        device, as each interface will be loaded into a separate driver instance. To

+ *        conbat this, you should use the "Interface Association Descriptor" addendum to

+ *        the USB standard which is available on most OSes when creating Composite devices.

+ *

+ *        Another major oversight is that there is no mechanism for the host to notify the

+ *        device that there is a data sink on the host side ready to accept data. This

+ *        means that the device may try to send data while the host isn't listening, causing

+ *        lengthy blocking timeouts in the transmission routines. To combat this, it is

+ *        recommended that the virtual serial line DTR (Data Terminal Ready) be used where

+ *        possible to determine if a host application is ready for data.

+ *

  *  @{

  */