ChibiOS 2.6.8, until I can figure out where to get it from git.

firmware/chibios/os/hal/dox/serial_usb.dox

@@ -0,0 +1,63 @@
+/*
+    ChibiOS/RT - Copyright (C) 2006,2007,2008,2009,2010,
+                 2011,2012,2013 Giovanni Di Sirio.
+
+    This file is part of ChibiOS/RT.
+
+    ChibiOS/RT is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 3 of the License, or
+    (at your option) any later version.
+
+    ChibiOS/RT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+                                      ---
+
+    A special exception to the GPL can be applied should you wish to distribute
+    a combined work that includes ChibiOS/RT, without being obliged to provide
+    the source code for any proprietary components. See the file exception.txt
+    for full details of how and when the exception can be applied.
+*/
+
+/**
+ * @defgroup SERIAL_USB Serial over USB Driver
+ * @brief   Serial over USB Driver.
+ * @details This module implements an USB Communication Device Class
+ *          (CDC) as a normal serial communication port accessible from
+ *          the device application.
+ * @pre     In order to use the USB over Serial driver the
+ *          @p HAL_USE_SERIAL_USB option must be enabled in @p halconf.h.
+ *
+ * @section usb_serial_1 Driver State Machine
+ * The driver implements a state machine internally, not all the driver
+ * functionalities can be used in any moment, any transition not explicitly
+ * shown in the following diagram has to be considered an error and shall
+ * be captured by an assertion (if enabled).
+ * @dot
+  digraph example {
+    rankdir="LR";
+    node [shape=circle, fontname=Helvetica, fontsize=8, fixedsize="true",
+          width="0.9", height="0.9"];
+    edge [fontname=Helvetica, fontsize=8];
+
+    uninit [label="SDU_UNINIT", style="bold"];
+    stop [label="SDU_STOP\nLow Power"];
+    ready [label="SDU_READY\nClock Enabled"];
+
+    uninit -> stop [label=" sduInit()"];
+    stop -> stop [label="\nsduStop()"];
+    stop -> ready [label="\nsduStart()"];
+    ready -> stop [label="\nsduStop()"];
+    ready -> ready [label="\nsduStart()"];
+    ready -> ready [label="\nAny I/O operation"];
+  }
+ * @enddot
+ *
+ * @ingroup IO
+ */