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Topic: removing atmega168 for standalone? (Read 1 time) previous topic - next topic


so, judging by this diagram ( http://www.arduino.cc/en/Hacking/Atmega168Hardware )of the pin-mappings for an atmega168, you should be able to remove the chip after burning it with the bootloader and a sketch for standalone operation, right? Simply connect inputs to corresponding pins on the chip, etc.?

You'd have to power it with a battery or some other power source (and I assume, regulate that power source to provide the correct voltage), and I suppose add resistors to compensate for the lack of the arduino's internal pull-up resistors, but it would work correctly otherwise, right?

Has anybody tried this? Maybe it's an obvious question.


It should work fine.  One thing, though.  You'll also need a 16 MHz oscillator and supporting capacitors, unless you change the fuses on the chip (using a hardware programmer) to work on the internal oscillator.  


Can the fuses be set and unset if needed ?


Yep.  You can also continue to run the ATmega from its internal clock when it's on the Arduino board, if you don't want to have to change the fuses every time.


It looks like the internal oscillator runs at 8mhz not 16mhz so timings maybe out !?


It should be fine.  The LilyPad also runs at 8 MHz, so I've adjusted most of the core to work at either speed.  The PWM frequency will be different, but everything should work (and the delays should be correct).


so I would connect an oscillator to the two pins marked 'crystal'? thanks so much for the help!



I'm also in process of breadboarding around a pre-burned ATmega168.

Picked up a handful of 16 mHz resonators at Digi-Key earlier this week.  As I understand it, a couple of filter caps, a regulated supply, and the resonator is most of what I need to get a "naked" Arduino running.

(I'm tinkering on a project where I just don't have space for the full diecimila and shield).


There is a page on the main site about using the controller by itself (with a few discreet components) on a breadboard



Or you could check the Real Bare Bones Board:


It think it will be hard, for a DIY project, to beat the 11$ pricetag and the ultra small footprint.



add resistors to compensate for the lack of the arduino's internal pull-up resistors

Unless I misunderstand you, what you refer to as "Arduino's internal pull-up resistors" are actually the "atmega168's internal pull-up resistors" so they are internal to chip and so "come along for the ride" when you make it stand-alone.


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