SPMA087 March   2023 TM4C1230C3PM , TM4C1230C3PM , TM4C1230D5PM , TM4C1230D5PM , TM4C1230E6PM , TM4C1230E6PM , TM4C1230H6PM , TM4C1230H6PM , TM4C1231C3PM , TM4C1231C3PM , TM4C1231D5PM , TM4C1231D5PM , TM4C1231D5PZ , TM4C1231D5PZ , TM4C1231E6PM , TM4C1231E6PM , TM4C1231E6PZ , TM4C1231E6PZ , TM4C1231H6PGE , TM4C1231H6PGE , TM4C1231H6PM , TM4C1231H6PM , TM4C1231H6PZ , TM4C1231H6PZ , TM4C1232C3PM , TM4C1232C3PM , TM4C1232D5PM , TM4C1232D5PM , TM4C1232E6PM , TM4C1232E6PM , TM4C1232H6PM , TM4C1232H6PM , TM4C1233C3PM , TM4C1233C3PM , TM4C1233D5PM , TM4C1233D5PM , TM4C1233D5PZ , TM4C1233D5PZ , TM4C1233E6PM , TM4C1233E6PM , TM4C1233E6PZ , TM4C1233E6PZ , TM4C1233H6PGE , TM4C1233H6PGE , TM4C1233H6PM , TM4C1233H6PM , TM4C1233H6PZ , TM4C1233H6PZ , TM4C1236D5PM , TM4C1236D5PM , TM4C1236E6PM , TM4C1236E6PM , TM4C1236H6PM , TM4C1236H6PM , TM4C1237D5PM , TM4C1237D5PM , TM4C1237D5PZ , TM4C1237D5PZ , TM4C1237E6PM , TM4C1237E6PM , TM4C1237E6PZ , TM4C1237E6PZ , TM4C1237H6PGE , TM4C1237H6PGE , TM4C1237H6PM , TM4C1237H6PM , TM4C1237H6PZ , TM4C1237H6PZ , TM4C123AE6PM , TM4C123AE6PM , TM4C123AH6PM , TM4C123AH6PM , TM4C123BE6PM , TM4C123BE6PM , TM4C123BE6PZ , TM4C123BE6PZ , TM4C123BH6PGE , TM4C123BH6PGE , TM4C123BH6PM , TM4C123BH6PM , TM4C123BH6PZ , TM4C123BH6PZ , TM4C123FE6PM , TM4C123FE6PM , TM4C123FH6PM , TM4C123FH6PM , TM4C123GE6PM , TM4C123GE6PM , TM4C123GE6PZ , TM4C123GE6PZ , TM4C123GH6PGE , TM4C123GH6PGE , TM4C123GH6PM , TM4C123GH6PM , TM4C123GH6PZ , TM4C123GH6PZ , TM4C123GH6ZXR , TM4C123GH6ZXR , TM4C1290NCPDT , TM4C1290NCPDT , TM4C1290NCZAD , TM4C1290NCZAD , TM4C1292NCPDT , TM4C1292NCPDT , TM4C1292NCZAD , TM4C1292NCZAD , TM4C1294KCPDT , TM4C1294KCPDT , TM4C1294NCPDT , TM4C1294NCPDT , TM4C1294NCZAD , TM4C1294NCZAD , TM4C1297NCZAD , TM4C1297NCZAD , TM4C1299KCZAD , TM4C1299KCZAD , TM4C1299NCZAD , TM4C1299NCZAD , TM4C129CNCPDT , TM4C129CNCPDT , TM4C129CNCZAD , TM4C129CNCZAD , TM4C129DNCPDT , TM4C129DNCPDT , TM4C129DNCZAD , TM4C129DNCZAD , TM4C129EKCPDT , TM4C129EKCPDT , TM4C129ENCPDT , TM4C129ENCPDT , TM4C129ENCZAD , TM4C129ENCZAD , TM4C129LNCZAD , TM4C129LNCZAD , TM4C129XKCZAD , TM4C129XKCZAD , TM4C129XNCZAD , TM4C129XNCZAD

 

  1.   Abstract
  2.   Trademarks
  3. 1Introduction
  4. 2How to Install
    1. 2.1 Update the FreeRTOS Version in the TivaWare Directory
    2. 2.2 Adding FreeRTOS Hardware Driver Files for TM4C LaunchPads
  5. 3Architecture for TM4C FreeRTOS Examples
    1. 3.1 Proper Clock Configuration
    2. 3.2 How to use Hardware Interrupts Alongside the FreeRTOS Kernel
    3. 3.3 Code Composer Studio Debug Support for FreeRTOS
  6. 4Example Project Walkthroughs
    1. 4.1 Download and Import the Examples
    2. 4.2 USB Examples
      1. 4.2.1 usb_dev_bulk
      2. 4.2.2 usb_dev_cdcserial
      3. 4.2.3 usb_dev_keyboard
    3. 4.3 Ethernet Examples
      1. 4.3.1 enet_lwip
        1. 4.3.1.1 Running enet_lwip Example
      2. 4.3.2 enet_io
        1. 4.3.2.1 Running enet_io Example
  7. 5References

4.3.2 enet_io

This example application demonstrates web-based I/O control using the TM4C Ethernet controller and the lwIP TCP/IP Stack. DHCP is used to obtain an Ethernet address. If DHCP times out without obtaining an address, a static IP address will be chosen using AutoIP. The address that is selected will be shown on the UART allowing the user to access the internal web pages served by the application via a normal web browser.

Two different methods of controlling board peripherals via web pages are illustrated via pages labeled IO Control Demo 1 and IO Control Demo 2 in the navigation menu on the left of the application’s home page. In both cases, the example allows the user to toggle the state of the LED on the board and set the rate for blinking the LED.

IO Control Demo 1 uses JavaScript running in the web browser to send HTTP requests for particular special URLs. These special URLs are intercepted in the file system support layer (io_fs.c) and control the LED and animation LED. Responses generated by the board are returned to the browser and inserted into the page HTML dynamically by more JavaScript code.

IO Control Demo 2 uses standard HTML forms to pass parameters to CGI (Common Gateway Interface) handlers running on the board. These handlers process the form data and control the animation and LED as requested before sending a response page (in this case, the original form) back to the browser. The application registers the names and handlers for each of its CGIs with the HTTPD server during initialization and the server calls these handlers after parsing URL parameters each time one of the CGI URLs is requested.

Information on the state of the various controls in the second demo is inserted into the served HTML using SSI (Server Side Include) tags which are parsed by the HTTPD server in the application. As with the CGI handlers, the application registers its list of SSI tags and a handler function with the web server during initialization and this handler is called whenever any registered tag is found in a .shtml, .ssi, .shtm or .xml file being served to the browser.

In addition to LED and animation speed control, the second example also allows a line of text to be sent to the board for output to the UART. This is included to illustrate the decoding of HTTP text strings.

The web server for this example has been modified from the example offered in the basic lwIP package. Additions include SSI and CGI support along with the ability to have the server automatically insert the HTTP headers rather than having these built in to the files in the file system image.

Source files for the internal file system image can be found in the fs directory. If any of these files are changed, the file system image, io_fsdata.h, must be rebuilt by running the following command from the enet_io directory:

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

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