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Topic: removing atmega168 for standalone? (Read 977 times) previous topic - next topic

grapewizardusa

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.

mellis

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.  

myozone

Can the fuses be set and unset if needed ?

mellis

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.

myozone

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

mellis

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).

grapewizardusa

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

mellis


nomuse

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).

trialex

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

http://www.arduino.cc/en/Main/StandaloneAssembly

MikMo

Or you could check the Real Bare Bones Board:

http://www.moderndevice.com/RBBB.html

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

MikMo
http://www.mikmo.dk


follower

Quote
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.

--Phil.

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