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Topic: Power saving (Read 1 time) previous topic - next topic

sbright33

I'm sure this has been asked before but I can't find it.  I heard that the ATmega328 chip uses about 10-20ma when idle.  My Uno is drawing 150ma.  Can I turn off the USB port if my Sketch doesn't use it?  I've read how to get it from 10 down to 3ma or less.  I know about powering down and sleep modes.  That is not my concern.  I want to get down from 150ma to 10-20ma.  How do I do it?
If you fall... I'll be there for you!
-Floor

Skype Brighteyes3333
(262) 696-9619

RuggedCircuits

What do you have hooked up to your Uno? Shields or other modules? It should not be drawing 150mA by itself unless something is wrong.

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The Gadget Shield: accelerometer, RGB LED, IR transmit/receive, speaker, microphone, light sensor, potentiometer, pushbuttons

sbright33

No hardware is connected for this test.  But I was running a Sketch.  Let me run an empty one?
Using 8v battery pack with multimeter to measure current.
If you fall... I'll be there for you!
-Floor

Skype Brighteyes3333
(262) 696-9619

sbright33

With an empty sketch
void setup() {}
void loop() {}
it's still 150ma.  Nothing is connected.  What am I doing wrong?
At 12v the regulator gets hot.
At 8v it does not.
If you fall... I'll be there for you!
-Floor

Skype Brighteyes3333
(262) 696-9619

RuggedCircuits

I'm not sure if you're doing anything wrong or if your Uno is damaged. It should really only draw about 25mA or so. Is this a "name brand" Uno or something a bit more...sketchy? Are any other components on the board getting warm at 8V?

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The Ruggeduino: compatible with Arduino UNO, 24V operation, all I/O's fused and protected

sbright33

My friend has 2 more that look exactly the same.  All Arduino brand Uno with socketed 328's.  The other 2 measure 50ma at 8v.  50 not 150.  So something is different about mine.  Still why 50ma?  How do I troubleshoot mine?
If you fall... I'll be there for you!
-Floor

Skype Brighteyes3333
(262) 696-9619

RuggedCircuits

Try removing the '328 from the socket. If the current changes by a lot, the '328 could be damaged. If it only changes by a little, something else on the board is bad.

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The Flexible MIDI Shield: MIDI IN/OUT, stacking headers, your choice of I/O pins

sbright33

The 328 gets warm on mine.  Cold on the others.  Easy to replace.  Why 50ma when it should be 25?  Any guesses how I blew it?
If you fall... I'll be there for you!
-Floor

Skype Brighteyes3333
(262) 696-9619

zoomkat

Are you measuring the current being input to the on board regulator from an external power source, or the current when inputting 5v directly into the 5v bus on the board? Also, does the board have a serial to USB chip on it?
Consider the daffodil. And while you're doing that, I'll be over here, looking through your stuff.   8)

CrossRoads

Easy to blow an output - one little short, damages an IO pin, part will seem to work in lots of areas and feel warm, or even quite warm to the touch.
Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
Arduino for Teens available at Amazon.com.

sbright33

I'm measuring the external power source.  Yes, it has the USB on it.  
If you fall... I'll be there for you!
-Floor

Skype Brighteyes3333
(262) 696-9619

zoomkat

Quote
I'm measuring the external power source.  Yes, it has the USB on it. 


Then you are measuring the power loss in the regulator chip (which may be more than half the loss) and and other gizmos plus the ATmega328 chip. You are not just measuring the ATmega328 chip current useage.
Consider the daffodil. And while you're doing that, I'll be over here, looking through your stuff.   8)

sbright33

So 50ma is about right.  At 12v the regulator is more than 1/2.
If you fall... I'll be there for you!
-Floor

Skype Brighteyes3333
(262) 696-9619

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