Here is a recipe for using the atmega168 as a standalone arduino. It uses the internal oscillator of the arduino running at 8mhz, and is powered at 3.3 volts. I used this together with a xbee radio modem for my wind-up birds project.
You can find out more about how I used the minimal arduino to control a xbee network here.
The only external components needed is a 0.1µF capacitor and a 1k resistor.
The tricky part is to get the firmware onto the chip. You need some sort of avr-programmer, I use the avr-hid developed by Martin Howse.
avr-hid+connector
This procedure is bypassing the bootloader which is used on the atmega chips that come with the arduino boards.
Different programmers use different layouts for the in-system programmer [ISP] header but for the avr-hid it is 1. MOSI, 2. V+, 3. x, 4. GND, 5. RESET, 6. GND, 7. SCK, 8. GND, 9. MISO, 10. GND
please read the instructions for your programmer carefully, there might be some headers for different settings.
I made a custom connector for the atmega168 since I needed to program many chips, also for outdoor use, but else you could of course just hook this up on a breadboard.
The connections:
MOSI – pin 17
MISO – pin 18
SCK – pin 19
RESET-pin 1
Remember to also hook up ground and power connections.
The software:
Open the arduino application.
Select lilypad as the board in the arduino tools menu. This is because the lilypad also runs at 8mhz.
Verify your arduino sketch, this creates a hex file in a tmp directory which will be used by avrdude.
Open a terminal program, you will access a program called avrdude to program the chip.
avrdude is installed with the arduino software (correct me if this is not the case for some platforms)
in the terminal, navigate to hardware/tools/avr/bin inside your arduino-0011 (or whichever version you are using) folder:
cd /Applications/arduino-0011/hardware/tools/avr/bin
copy the temporary sketch into this directory:
cp /tmp/build*/[filename].hex .
then after making sure your avrprogrammer is connected with a chip ready to get programmed, enter:
./avrdude -C ../etc/avrdude.conf -p m168 -c usbasp -U flash:w:[filename].hex -U lfuse:w:0xE2:m -U hfuse:w:0xDF:m
It was a lot of contradictory information online about the fuse settings, but at least we have had no problems with the above settings.
If everything goes well you will eventually get this message: “avrdude done. Thank you.”
Your minimal arduino is ready to be used!
This might be a useful diagram when programming and hooking up external components:
arduino atmega 168 pinmap from the arduino website:
December 4, 2008 at 14:49
[...] is a link to the first technical post related to the project, which covers how to program and hook up a atmega168 as a minimal arduino standalone, using the internal oscillator running at 8mhz and 3.3 volts. Possibly related posts: [...]
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[...] first tech-post is about how to program and hook up a atmega168 chip as a minimal arduino standalone, consuming less power and being much cheaper. It uses the internal oscillator running at 8mhz and [...]
April 24, 2009 at 17:03
[...] Standalone Arduino Once you’ve developed something it can be stripped right back to just one chip. [...]
June 17, 2009 at 22:25
I use this page as a reference in all of my Arduino hardware designs. This is a great compilation of all the things needed to have a working Arduino with only a few parts. (Shaving the oscillator saves you about a buck each.) It should be noted that without a precision oscillator, it is unlikely that the serial will work at any high baudrate due to clock synchronization issues.