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Arduino Micro: Current pull in sleep mode?

by daveoei on Wed Jan 16, 2013 1:58 pm

Hello!

I'm creating a low power outdoor sensor unit and am on the fence on whether to use the Boarduino or the new Arduino Micro. I prefer the Micro as there's no setup involved, but I've created a few Boarduinos with success and will use it if necessary.

I've found that when I power the Boarduino off a regulated 5V supply directly to the 5V and Ground pins and put it into a deep sleep, it pulls approximately 3 mA. That's about 10x better than what I can do off an Uno when hooked up similarly. So, between the Uno and Boarduino - it's a no brainer, the Boarduino is in the lead.

However, I'm intrigued by the Micro. It's better for me if I can use the Micro as it's an off-the-shelf device that will make construction a lot easier. However, I'm wondering: If I were to power the Micro through the 5V and Ground pins and put it to sleep, would I see a current draw more similar to the Uno ... or the Boarduino?

Thanks!

Best,

Dave
daveoei
 
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Re: Arduino Micro: Current pull in sleep mode?

by BruceF on Wed Jan 16, 2013 2:53 pm

Did you have a power-on LED on that Boarduino? If so, I'd guess that 3mA is all being used there, because according to the datasheet an ATmega328P in power-save mode (which I'm assuming is what's being used when in "deep sleep") pulls a few microamps.

My *guess* from looking over the Arduino Micro schematic on arduino.cc is that you should be able to get sleep current in the uA range if you desolder the power-on LED, and the same if you don't solder in the same LED on a Boarduino. I've not tested any of this though, so hopefully some smarter, more experienced and better looking commenters could confirm or refute that conclusion?

If you're really going for power savings, explicitly set any unused pins to digital inputs and enable their pull-up resistors. (See 14.2.6 of the complete datasheet here.)
- Bruce
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Re: Arduino Micro: Current pull in sleep mode?

by daveoei on Wed Jan 16, 2013 3:45 pm

Hi Bruce,

Thanks for your reply! Yes, I kept the green LED in place because despite my desire to keep this a low power unit, having an "on" indicator is also important and 3mA is in the range of what I can afford from a power-standpoint.

My best guess is that, yes, the Micro will draw the same amount of current as a Boarduino. But, I'm far from an EE. So I was hoping for a definitive answer before biting the bullet.

Best,

Dave
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Posts: 5
Joined: Sat Jan 14, 2012 12:56 am