The Mega32 webserver project
The purpose to have a serially attached webserver was to provide a self contained GUI
for applications where an ethernet connection was overkill. This may occur in cases,
where not very often a few bytes were to be communicated to configure an embedded
device. We thus get a webserver running from a few (single digit) mA current at a
cost not exceeding 3 Euros at 100 Units.
And yes, a proxy is required to route the IP strean onto the serial port. With a
modern language and few components this is a quick and trivial task. I might publish
it when timer permits. The collaborating company AjaxUp
provides free proxy, that is much better though.
During the development of the Mega169 (Butterfly) webserver, it soon became apparent
that the available 16k were rather tight for a compiler. But a compiler was neccessary
for fast development, especially while the specifications were a moving target. Now,
after having written a http:// bootloader I'm
confident to fit a minimal and compact webserver into the 8k of a Mega8. But for a
more comfortable development and richer functionality I'll rather stick with the
Mega32 for now.
The requirements for the Mega32 webserver
In the Butterfly webserver project we were quite satisfied with the Atmel
Dataflash as external Flash storage for the webpages. They offer a pin compatible
range of devices starting from 128k to 8 MBytes in basically two available
cases, the SO8 and a TSOP28, other cases are rather hard to get.
- processes the http requests and answers appropriately.
- provides a default page which enables the uploading of web pages
- supports 512k attached Dataflash in bitbang mode, leaving the SPI for the application
- is able to jump into the bootloader
- provides basic code protection by a CRC
- doesn't provide IP protection, as the webpages are to be viewed anyway
- doesn't provides basic user authentication by a pin code yet
- sends just ASCII over the line to stay compatible, no binary
- a generous timeout on incoming messages wouldn't leave the
webserver in a forgotten state
Coming a bit later....
A product on this is planned, but needs a few more touches.
More is coming soon ...
the Mega32 bootloader
embedded AVR page
last updated 27.Feb.08 or perhaps later
Copyright (99,2008) Ing.Büro R.Tschaggelar