How to measure the current that my board draws

I have this stand alone Arduino that I've been programming to be low power. I turn off the ADC, disable the BOD and put it to sleep mode etc. But the current I have been measuring seems to be wrong. I googled how to measure current in breadboard project but they all confused me.

Can somebody please explain to me how can I measure the current that my board draws?

You can see the way I hooked my multimeter in the picture. Yellow crocodile connected to red mA cable of the multimeter, black goes to ground and the red cable on the breadboard goes to my 3.3V regulator as in Vcc.

Place your DVM (set to the amperage range) in the current path of the wires supplying power to your circuit.

How to post an image

Your photo is not helpful as it is impossible to see where any of the wires go off the board. A schematic would be more help, had drawn and photographed is fine.

I appreciate your effort to keep this forum as clean as possible but sometimes I feel like you guys can be overly sensitive and mean about this matter. For a beginner like me, it is sometimes discouraging to see replies like the PerryBebbington's. Because photo is pretty clear to me, it's a stand alone Arduino Pro Mini that works fine and has been used in other projects. I'm just showing and explaining you the part where I hooked up my multimeter because I'm just simply asking how can I measure the current that ANY breadboard system draws. It's a very fundamental question which I I haven't just yet learned in my high school and the stuff I found on internet just wasn't sufficient.

Even if you are an expert, with all due respect, please ask yourself this question ''Will I be any of help by writing this?" before replying to posts. Because we beginners value your suggestions and believe in open source community. I personally have gotten many help from this forum, so whenever somebody replies to my post I just naturally run to my computer because I know I'll learn something new. Anyways, sorry if I have been rude. Maybe it's because I'm frustrated and wanted to share my opinions.

Thanks to anyone that try to genuinely help tho.

Review this video:

Others are available too.


Is there anything you have trouble understanding ?

For a beginner like me, it is sometimes discouraging to see replies like the PerryBebbington's. Because photo is pretty clear to me.

Thank you for the feedback, no problem. I meant you no discouragement, sorry if that was the effect.

While the photo is clear in of itself it is not helpful because it does not show half of what I need to see; it does not show where all the wires going off the sides go to. All I can see is a load of coloured wires disappearing in all directions to I do not know what.

Even if you are an expert, with all due respect, please ask yourself this question ''Will I be any of help by writing this?"

The answer is yes, unequivocally. I stated in a few words what information I would need to provide you with the information you are seeking. If you provide a schematic I, and many others, will provide the information you need. I also showed you how to post images properly, which I happen to think is a pain in the ... , but there is nothing I can do about that.

Maybe the video Larry provided a link to has answered your question, I don't know.

Good luck with your project.

Thank you for the replies. You guys are really thoughful. I checked out the link, it's a very helpful one. Yet I'm still confused about where to wire my multimeter so it measures the current the board draws. I mean the whole board not a particular LED or a component.

I should see the current path here, right? And then I connect my multimeter serailly to the path. So with this in mind, I connected a wire out of the Vout of my regulator. Because this is where the current enters the circuit. And then I conected a 1k resistor. (I did this because if I didn't I would be sucking all the current directly to the ground thus resetting the circuit.) Then connect the mA probe of multimter to the 1k and ground of the multimeter to the ground. Again I'm attaching a photo. (Sorry PerryBebbington, I couldn't quite figure out how to give an URL to save you guys from downloading it. Because the photo is in my computer. But I will learn it after I measure this darn current right :slight_smile: )

By making this multimeter connection to my board, do you guys think that I'm measuring the right current? Or am I even doing the measurement right?

And here's the schematic I drew for this project. Some of the things you see in the schematics are not present on my board right now. I plan to add them later on. But you can have the basic idea of my connections. Sorry the image quality is poor when you zoom. If you have DipTrace, I can maybe send the actual DipTrace file.

Thanks again.


Hello cglkr97,

And here's the schematic I drew for this project. Some of the things you see in the schematics are not present on my board right now. I plan to add them later on. But you can have the basic idea of my connections.

I cannot tell from that where the power goes in as the schematic shows a DC power jack that does not exist on your photo. You should measure the supply current by interrupting one of the wires into the jack and inserting your meter in series there.

It is clear from the photo that you are measuring the current the wrong way, but not clean where you should be measuring it on your breadboard as I do not know where the power goes in. I have no idea why you have connected it to the 1k resistor but that is wrong. If the black lead is connected to the -ve input from the supply then the other lead should go to the PSU -ve output.

Please provide a schematic of what you have built, and please make sure it is readable.

Thank you.

BTW if you want low current consumption you must make any unused pins either INPUT_PULLUP or OUTPUT.
Leaving them as INPUT can lead to many mA of current draw due to floating inputs.

In a nutshell, Voltage measurement is across the supply, current measurement is in series with the supply.

AJLElectronics:
In a nutshell, Voltage measurement is across the supply, current measurement is in series with the supply.

Here's a pic of that if it helps:

cglkr97:
I appreciate your effort to keep this forum as clean as possible but sometimes I feel like you guys can be overly sensitive and mean about this matter. For a beginner like me, it is sometimes discouraging to see replies like the PerryBebbington's. Because photo is pretty clear to me, it's a stand alone Arduino Pro Mini that works fine and has been used in other projects.

With all due respects, its not a Arduino Pro Mini.

The 28pin DIP version of the ATmega328P does not have the A6 and A7 pins, the surface mount version of the ATmega328P, as used on the Pro Mini's, does have A6 and A7 pins ................................