Adjusting Current does nothing

Hi everyone, I am adjusting the current on a Pololu DRV8825 using Arduino Uno.
My diagram looks like this:

My external power source is a 9V battery.

My issue is that, as I turn the current dial, I get weird current numbers. I turn it a bit, I get 6, turn it more, get 5. Turn a little bit more, I get 0.8. Great I think! I try connecting a motor (when it’s disconnected from power) - but when I try try to power it on it makes a high pitched noise, and attempts at turning, but it doesn’t. I measure my current again - and now it reads 3.5. How did my current change from 0.8 to 3.5 without turning the dial?

Am I doing something seriously wrong? Thanks


I am sorry you are having trouble with your DRV8825. There are a couple things I noticed about your setup. First, a 9V battery is not an appropriate supply for powering motors. You can learn more about why that is in this blog post about understanding battery capacity. Second, although it is difficult to be sure with your Fritzing diagram where you are not using our stepper motor driver, the general layout of your connections makes it look like you are missing some of the minimal connections needed to get the board working. Can you try connecting !SLEEP to !RESET like it shows at the bottom of the product page for the DRV8825?

Alternatively, you can disconnect !FAULT, and connect !SLEEP and !RESET to your logic power supply like it shows in the diagram under the “Using the driver” section of the product page.

If things are still not working after switching out for a more appropriate power supply, can you post pictures that clearly show your connections? Also, it is not clear what the numbers you obtained represented (i.e. milivolts or amps). Can you describe specifically what you are using to measure those values and how you are connecting it to your setup?


Hi Josh, thanks for your email -unfortunately your email was put in my spam
folder, that’s why I didn’t reply sooner. I will have a look at your email
more closely when I get home.


Thanks for all your help again -

I finally got it working by connecting “sleep” and “reset” together as you

Unfortunately, the pololu chips are all bad - it was probably due to my
soldering although I swear that the job I did was quite okay. I had to
resort to buying Chinese clones because I was unable to find pre-soldered
pololu drivers anywhere in Europe.

Thanks again,

I am sorry to hear that your drivers are not working. If you post pictures of your setup that clearly show all of your connections, I can check to see if there is anything else that might have obviously been amiss (in case soldering is not the issue).

If you decide you want to try soldering a new set of drivers yourself again, I recommend reading through Adafruit’s Guide to Excellent Soldering. In particular, the picture at the top of this page should be a useful visual guide for inspecting your own soldering joints.