The heart of the Arduino is the ATMEGA chip. The rest is only decoration! Decoration needed to get your program at the right spot, so useful decoration in the end. When you have an Arduino you can change programs all the time, but that means you always loose the last experiment. So buying the ATMEGA heart and storing your program on it, wiring the sensors and other elements definitively together you can save your stuff, without buying another Arduino.This saves you about 20 euro’s, but you have to do something 4 it!
The atmega168 can be bought for 4 .5 euro’s, with the 28 pin foot about 5.
This chip has to be bootloaded, so that the Arduino software can write to it. Crosslab has AVRISPmkll as an external programmer.
It took me a while to find out which hexfile to load. The Duemilanove needed the ATmegaBOOT_168_ng.hex, the configs given on the page http://www.arduino.cc/playground/Learning/Burn168
configs, fuses, whatever — were ok, but the bootloader to be downloaded (ATmegaBOOT_168.hex) was not. (Although indicated on the Arduino playground page.)
Be careful with the fuses and never set the disable reset pin!!! See below or: http://tinker.it/now/2007/02/24/the-tale-of-avrdude-atmega168-and-extended-bits-fuses/
The fact that it was not working could be checked when resetting: the LED 13 did not light up. Then transferring a script from the Arduino software gave an error.
With the right bootloader HEX file, the reset worked, and the transferring too.
Ok with this knowledge and experience, we can quickly make ready and program ATMEGA 168IC’s and use them for our projects. The chip can be sewn in clothing making smart textiles.
link adaboot: http://wulfden.org/TheShoppe/freeduino/ADABOOT.shtml
One of the ten ATMEGA168 refused to get flashed, it was one of the first, and suffered probably a setting of the DISABLE RESET PIN. That is something to be avoided next time. The solution will cost a bit of extra effort and time: high voltage programming and making a shield: http://mightyohm.com/blog/2008/09/arduino-based-avr-high-voltage-programmer/
may be that Do-It-Yourself is for another day!
for the moment 9 out of 10 ATMEGA168’s are bootloaded…
The last ATMEGA has to what for high voltage programming (well high = 12V)
link for the AVR if you want to program in assembler (only then u r a real ‘man’) _ http://www.howtofriends.com/avr/
good ATMEGA info: http://en.wikipedia.org/wiki/Atmel_AVR
pinmapping: http://www.arduino.cc/en/Hacking/PinMapping168
connecting the ATMEGA168 “naked”: http://itp.nyu.edu/physcomp/Tutorials/ArduinoBreadboard
or http://blog.makezine.com/archive/2007/07/barebones_arduino_on_a_br.html
later on I found the best link explaining about the ATMega168:
https://www.sparkfun.com/commerce/tutorial_info.php?tutorials_id=93
and all about oscillators:
https://www.sparkfun.com/commerce/tutorial_info.php?tutorials_id=95
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