S2E application with lwIP and FreeRTOS

The S2E application implements a serial-to-Ethernet module that provides a
means to access the UART port on a TM4C129x device via an Ethernet link.
The UART can be connected to the UART on a non-networked device.  This can
be useful to overcome limitations such as adding multiple serial devices to
a shared network and inability to access the device from long distances
without modifying the serial device.  Telnet protocol is used to transfer
the serial data over Ethernet.  Two Serial-to-Telnet ports are implemented.

The application uses lwIP Stack to manage TCP/IP layers.  DHCP or Static IP
configuration can be used to obtain an IP address.  If DHCP configuration
is used, and it times out without obtaining an address, AutoIP will be used
to obtain a link-local address.

FreeRTOS is used to perform a variety of tasks in a concurrent fashion.
The following tasks are created:
* An Ethernet task to manage the Ethernet interface and its interrupt.
* A TCP/IP task to run the lwIP stack and manage all the TCP/IP packets.
  This task works very closely with the Ethernet task to server web pages,
  handle Telnet packets and Locator app packets.  Ethernet and TCP/IP tasks
  are managed by lwIP.
* A serial task to manage the serial peripherals and their interrupts.
* An idle task (automatically created by FreeRTOS) that manages changes to
  the IP address and sends this information to the user via Debug UART.

To build this application, install TivaWare for C Series v2.1.0.12573 or
higher and copy the "enet_s2e" application folder into the EK-TM4C1294XL
board's folder at <TivaWare_Install_Folder>/examples/boards/ek-tm4c1294xl.

The IP address and other debug messages are displayed on the Debug UART.
UART0, connected to the ICDI virtual COM port, is used as the Debug UART.
115,200 baud with 8-N-1 settings is used to display debug messages from
this application.

The finder application (in ../../../../tools/bin/) can also be used to
discover the IP address of the board.  The finder application will search
the network for all boards that respond to its requests and display
information about them.

A configuration webserver is hosted to provide a convenient interface to
manage the various configuration options.  To access the webserver, enter
the IP address of the S2E module in a web browser.  The following command
can be used to re-build any file system files that change.

  ../../../../tools/bin/makefsfile -i fs -o enet_fsdata.h -r -h -q

For additional details on FreeRTOS, refer to the FreeRTOS web page at:
http://www.freertos.org/

For additional details on lwIP, refer to the lwIP web page at:
http://savannah.nongnu.org/projects/lwip/

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Copyright (c) 2014-2015 Texas Instruments Incorporated.  All rights reserved.
Software License Agreement

Texas Instruments (TI) is supplying this software for use solely and
exclusively on TI's microcontroller products. The software is owned by
TI and/or its suppliers, and is protected under applicable copyright
laws. You may not combine this software with "viral" open-source
software in order to form a larger program.

THIS SOFTWARE IS PROVIDED "AS IS" AND WITH ALL FAULTS.
NO WARRANTIES, WHETHER EXPRESS, IMPLIED OR STATUTORY, INCLUDING, BUT
NOT LIMITED TO, IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE APPLY TO THIS SOFTWARE. TI SHALL NOT, UNDER ANY
CIRCUMSTANCES, BE LIABLE FOR SPECIAL, INCIDENTAL, OR CONSEQUENTIAL
DAMAGES, FOR ANY REASON WHATSOEVER.

This is part of revision 2.1.0.12573 of the EK-TM4C1294XL Firmware Package.
