July 15th, 2008

Webserver Based On ATMega88

Webserver Based On ATMega88

Before starting this Ethernet project the author did of course some prototyping and then he noticed alreadythat UDP was not a problem with lots of space left on the atmega88. Therefore he 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.

As you can imagine this web-server code is written for a friendly environment. Don’t put it on the open internet. The code uses e.g the incoming packet to build from it the outgoing packet. An attacker who sends a mal formed IP packet might be able to confuse the TCP/IP stack. The code is verified with a lot of different browsers and a number of operating systems. It was tested Linux, BSD Unix, Win 98, Win XP, Mac OS-X with a number of different web browsers. It works very well but it was not tested agains atacks and destroy tests.

Webserver Based On ATMega88: [Link][via]

Interfacing Your Computer to an ADC via the Parallel Port

Interfacing an Analog-to-Digital Converter (ADC) with Linux via the parallel port is fairly simple. There two major areas that need to be addressed – hardware and software. The hardware consists of the parallel port, an ADC, and an analog signal source. The software we programmed in ‘C’ language.

Interfacing Your Computer to an ADC via the Parallel Port: [Link]

 SlugBee - Adding Zigbee Radio to a Slug

Zigbee, formally IEEE 802.15.4, is another short-range radio standard that uses the 2.4 GHz “microwave oven” band, alongside wireless Ethernet and Bluetooth. Compared to these others, Zigbee is most suited for low-power applications involving simple microcontrollers, for example wireless sensing, home and industrial automation, and so on. Its basic parameters are a data rate of up to 250 kbits/s and a typical range of 50 m.A small Linux box like the NSLU2 (aka Slug: 266 MHz XScale ARM processor, filesystem on a USB flash drive, takes about 5W, runs Debian GNU/Linux and other distributions) could be useful in a Zigbee deployment. For example, an always-on Slug could be responsible for logging data sent by remote sensors, and generating graphs on web pages, sending email alerts and so on.

SlugBee – Adding Zigbee Radio to a Slug: [Via][Link]

the Green PC Due to the holiday season up next the linux OS will get a great chance to become more popular than it is at Wal-Mart Stores. They were taking orders online Wednesday for a computer called the “Green gPC” that is made by Everex of Taiwan, costs $199 and runs Linux.

It will be available in about 600 stores, as well as online, Wal-Mart said. A comparable Everex PC preinstalled with Windows Vista Home Basic and more memory costs $298 partly because the manufacturer has to pay Microsoft Corp. for a software license, so I think people will like the new computer and discover the goods of linux.

Both computers come with keyboard, mouse, and speakers, but without a monitor. As you already may know Linux is developed and offered on a open-source basis by individuals and companies around the world.

It’s being used especially on servers because of its high stability on long term use. The variant of Linux on the gPC is called gOS and is derived from the popular Ubuntu variant. It’s mostly oriented toward Google’s Web sites and online applications, like YouTube, Gmail and the company’s word processing program, all of which can be used only when the computer is connected to a broadband line.

The PC comes with a dialup modem, but gOS doesn’t support it. So most users likely will get online using other ways. Google’s entrance to the OS market is relatively new and I think gOS will be a great chance for users who would like to move away from Microsoft and windows to something new and better.

Wal-Mart spokeswoman Melissa O’Brien said it is stocking the computer in about one in eight stores to test the demand for an open-source product. The gPC has a low-end processor from VIA Technologies, plus 512 megabytes of internal memory, an 80-gigabyte hard drive and a combination DVD drive and CD burner. Everex says the processor is very energy efficient, meriting the “Green” part of the name.

here is a screenshot of the gPC or you could call it a gOS screenshot:

gOS screenshot

Sources :




Also if you would like to see more gOS screenshots you should check this article of mine.

Install SNMP (Simple Network Management Protocol) on Debian     I’m writing this tutorial to help other that may have the same problem I had. Let me explain to you: I have a Debian server called debian1 which has external ip on eth0 and a local ip on eth0:1, and a second Debian server called debian2 which only has local ip on eth0. I need to access debian2 with ssh from the internet. I cant do that directly because debian2 does not have an external ip address to connect to the internet. But we can use a port forwarding rule on debian1 so that I can access debian2 trough debian1 on a specific port. The only command you have to use is:

iptables -A PREROUTING -t nat -p tcp -i eth0 –dport 88 -j DNAT –to

after entering this command debian1 will forward any request on port 88 from eth0 to on port 22. Now all I have to do is to enter port 88 in putty and I can log-in to debian2 trough ssh. That’s it short and simple about port forwarding.

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