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Topic: Uno Current Draw (Read 1 time) previous topic - next topic

jogl8

Can anybody tell me about what an Uno draws when powered by 12vdc on the barrel jack and no other devices or shields attached?

Thanks.

AlxDroidDev

That depends on the sketch that it is running.

It is possible to make it draw just a few milliamps (or even microamps) if the sketch takes the Atmega328 to sleep and disable several functions.

User Nick Gammon has written a great article about this subject.
Some of my projects:
Shield for DS1337+, DS1624 and AT24C1024B (RTC, temp & mem): http://forum.arduino.cc/index.php/topic,126197.0.html
CHDK Camera remote shutter (BT, IR, USB): http://forum.arduino.cc/index.php?topic=295377.0

Datman

He's talking about Arduino Uno board, not only the microcontroller...
Current drawn by the microcontroller only depends on clock frequency and loads on the outputs (and how often they are turned on).
My audio cable tester draws only 3.5mA from a 9V battery when all LEDs are off, but it is clocked at 1MHz by internal oscillator divided by 8.
Hi,I'm Gianluca from Roma.I play&work with electronics since I was16(1984).
After 25yrs of maintenance on cameras&video mixers,since 2013myJob is HDTVstudios design.
Since Jan2015 IPlayWith Arduino:bit.ly/2F3LPWP
Thanks 4 a Karma if U like my answer

septillion

Current drawn by the microcontroller only depends on clock frequency and loads on the outputs (and how often they are turned on).
No it does not. Also on the ADC being turned on or off. Same for timers.

And if someone says Arduino Board I think that includes the micro. It's on there...

But first step to make it draw less current? Remove the power led.
Use fricking code tags!!!!
I want x => I would like x, I need help => I would like help, Need fast => Go and pay someone to do the job...

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https://github.com/septillion-git/FadeLed

Datman

#4
Jan 12, 2016, 11:43 am Last Edit: Jan 12, 2016, 01:11 pm by Datman
No it does not. Also on the ADC being turned on or off. Same for timers.
That's right, but at 1/10 clock frequency current drawn is about 1/7!
If you need a very, very low power system you have firstly to reduce clock frequency to the minumum you can accept, then disable what you don't need, slower ADC, lower power supply voltage, use low power low dropout regulators (switching if it is advantageous).
Hi,I'm Gianluca from Roma.I play&work with electronics since I was16(1984).
After 25yrs of maintenance on cameras&video mixers,since 2013myJob is HDTVstudios design.
Since Jan2015 IPlayWith Arduino:bit.ly/2F3LPWP
Thanks 4 a Karma if U like my answer

AlxDroidDev

Current drawn by the microcontroller only depends on clock frequency and loads on the outputs (and how often they are turned on).
Not true. You're absolutely wrong.

The uC is on the board, and it consumes power, so it has to be factored in the calculations.

The LED + supply current of the USB-to-UART bridge voltage regulatores will take a few milliamps, but the uC is still the biggest culprit for large current draws of the UNO board. A sketch can minimize this or more than triple that value.

Since I've already posted a link from Nick Gammon's site, I'll not repeat myself. Just read his article and you'll understand what I mean. In short: you can tweak a sketch to drastically minimize current drawn by the uC and the board.



Some of my projects:
Shield for DS1337+, DS1624 and AT24C1024B (RTC, temp & mem): http://forum.arduino.cc/index.php/topic,126197.0.html
CHDK Camera remote shutter (BT, IR, USB): http://forum.arduino.cc/index.php?topic=295377.0

jogl8

Thanks guys.

I was wondering what an Uno with no alterations and no energy saving code would draw.  Looks like 50 to 100 mA.  As soon as I have a chance I will verify this.

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