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+system/cdcacm
+^^^^^^^^^^^^^^^
+
+  This very simple add-on allows the USB CDC/ACM serial device can be dynamically
+  connected and disconnected from a host.  This add-on can only be used as
+  an NSH built-in command.  If built-in, then two new NSH commands will be
+  supported:
+
+    1. sercon - Connect the CDC/ACM serial device
+    2. serdis - Disconnect the CDC/ACM serial device
+
+  Configuration prequisites (not complete):
+
+    CONFIG_USBDEV=y                 : USB device support must be enabled
+    CONFIG_CDCACM=y                 : The CDC/ACM driver must be built
+    CONFIG_NSH_BUILTIN_APPS         : NSH built-in application support must be enabled
+
+  Configuration options specific to this add-on:
+
+    CONFIG_SYSTEM_CDCACM_DEVMINOR : The minor number of the CDC/ACM device.
+                                    : i.e., the 'x' in /dev/ttyACMx
+
+  If CONFIG_USBDEV_TRACE is enabled (or CONFIG_DEBUG and CONFIG_DEBUG_USB, or
+  CONFIG_USBDEV_TRACE), then the add-on code will also initialize the USB trace
+  output.  The amount of trace output can be controlled using:
+
+  CONFIG_SYSTEM_CDCACM_TRACEINIT
+    Show initialization events
+  CONFIG_SYSTEM_CDCACM_TRACECLASS
+    Show class driver events
+  CONFIG_SYSTEM_CDCACM_TRACETRANSFERS
+    Show data transfer events
+  CONFIG_SYSTEM_CDCACM_TRACECONTROLLER
+    Show controller events
+  CONFIG_SYSTEM_CDCACM_TRACEINTERRUPTS
+    Show interrupt-related events.
+
+  Note:  This add-on is only enables or disable USB CDC/ACM via the NSH
+  'sercon' and 'serdis' command.  It will enable and disable tracing per
+  the settings before enabling and after disabling the CDC/ACM device. It
+  will not, however, monitor buffered trace data in the interim.  If
+  CONFIG_USBDEV_TRACE is defined (and the debug options are not), other
+  application logic will need to monitor the buffered trace data.