embedded webserver.


Posted on Feb 5, 2014

This is a continuation of the article An AVR microcontroller based Ethernet device. The hardware is still the same (ENC28J60 + atmega88). The software is now updated to provide also a web-server. That is: instead of using a command line application and send UDP packets to the Ethernet device we can just point our web browser to it. . and even bet


embedded webserver.
Click here to download the full size of the above Circuit.

ter: we add only the web server and all the UDP based functionality is still there. Now you can use both! A UDP command interface is sufficient for most applications but an integrated web-server is much more universal and easier to use. How to build a web server into an atmega88 chip Before starting this Ethernet project I did of course some prototyping and then I noticed already that UDP was not a problem with lots of space left on the atmega88. Therefore I was quite confident that TCP + HTTP will work. TCP/IP was invented more than 25 years ago. Todays microcontrollers provide almost the computing power a standard computer had at that time. No java or xml was used at that time. Things were done in smart and efficient ways. TCP is a protocol where one establishes a connection. For this a number of packets are first exchanged and both sides of the connection go through several states [see tcp state machine from rfc793]. Once the connection is established a number of data packets can be sent. More than one packet, large amounts of data can be sent. Counters and the state machine ensure that the actual user data arrives in correct order and without data loss. Let`s take a look at the application introduced in the first article [June 2006, article060601]. In this first article we just switch on and off something. It can be done with a simple web page which might look like this: Other applications might be measurement of...




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