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Author Topic: Standalone atmega328 on breadboard.  (Read 1038 times)
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 I want to use the arduino to control a motor that is connected to a breadboard. I want to have the ATmega328 from the Arduino Uno or a new one on the breadboard itself and running on batteries. How can I do that? Also since the motors are 3V motors, is there any way I can run the ATmega328 on a 3V battery supply?
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Yes to all of the above. The system clock frequency will need to be slowed down to operate at 3V, suggest using 8MHz (Uno runs at 16MHz). I do a lot of breadboards, see the most recent couple posts on my blog.
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Hey guys,
I don't want to muddy up the issue but shouldn't he shoot high on voltage supply and regulate down? I know that Vregs are very inefficient and maybe i'm just paranoid but i would be leery of plugging my u-controller into an untamed voltage source. Also my paranoia may just stem from me not knowing how stable batteries are or the possible things that could go wrong. Maybe I should be asking that question instead of projecting my paranoia on someone else's project.

my 2cents
Tyler
« Last Edit: March 14, 2012, 09:44:38 pm by TylerS » Logged

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Batteries are fine. Microcontrollers are intended to be powered by batteries (as well as by other things). An ATmega328(P) will run on as little as 1.8V. Batteries aren't "untamed", actually the purest DC comes from batteries. Battery voltage does decrease over time of course. But the ATmegaXX8 family also has a built-in "brown out detector" (BOD) which will hold the chip in reset and prevent it from running below a certain voltage (several voltage levels are selectable). Just remember that the maximum system clock speed is directly proportional to supply voltage, i.e. the higher the supply voltage, the faster the chip can be run, select clock speed and BOD level (if desired, I know some folks don't worry much about it) accordingly.

See the ATmegaXX8 family datasheet, section 29.3 Speed Grades, and table 29-13 BOD Fuse Coding.
« Last Edit: March 14, 2012, 09:59:05 pm by Jack Christensen » Logged

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You sir, have been incredibly helpful. Every reply you have made is not only accurate but extremely informative and well explained with direction to further learning. Above and beyond sir. Thank you.

Cheers,
Tyler
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Occasionally I will screw up Big Time, so it all averages out smiley-lol

I do have a couple ATmega328Ps around that run quite happily on a pair of AA cells. I've also experimented a bit with a couple of the ATtiny series, same for them.
« Last Edit: March 15, 2012, 06:09:37 am by Jack Christensen » Logged

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Thanks so much. Everyone. Jack, your blog is extremely helpful. Thanks a lot for your help.
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Thanks so much. Everyone. Jack, your blog is extremely helpful. Thanks a lot for your help.

Blogging is harder work and takes more time than I thought it would. As a result that blog is not as well organized or as extensive as I would like. But I'm really glad to hear that you found it of some small use, always glad to help if I can!
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Hey guys,
I don't want to muddy up the issue but shouldn't he shoot high on voltage supply and regulate down? I know that Vregs are very inefficient and maybe i'm just paranoid but i would be leery of plugging my u-controller into an untamed voltage source. Also my paranoia may just stem from me not knowing how stable batteries are or the possible things that could go wrong. Maybe I should be asking that question instead of projecting my paranoia on someone else's project.

my 2cents
Tyler
I disagree. Batteries are pure DC and fairly stable.
They do decrease as noted by the other poster but this is rarely a problem. I would avoid a regulator if at all possible since they are inefficient and I have lost an FTDI chip from one that has gone short. If this input is less then the chip maximum, it is less chance of blowing things up.
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Knowing what i know now after a few days of reading on batteries and supplying power in general I also disagree with my original post. My original concern was mostly for stability as a wonky power source could cause a lot of issues but as you say batteries are fairly stable and I don't think it would be an issue
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