A4988 driver issues?

Hello !
I am contacting you directly on your website because your driver is the only component of my (rather simple) setup that I don’t fully understand and I can’t seem to control a stepper motor with it, I’ve been rummaging through the internet for the last 2 weeks to find a solution or an answer but I couldn’t find anything.
I have reduced my montage to the components below
Here are the components as well as their specs :

  • Arduino mega 2560 (verified official brand)

  • A classic stepper motor with the Nema 17 casing :
    o Amperage : 0.9A
    o Operating Voltage : 5.4V

  • Polulu step motor driver A4988 (counterfeit ?)
    o 1.2 A per phase
    o Motor voltage from 8 to 35 Vcc

  • AC to DC adapter
    o Out Amperage : 3 A
    o Out Voltage : 5 Vcc
    o I’ve adapted the extremity (OUT) to be wirable to the breadboard

  • I’ve also added a decoupling condensator on the breadboard following the motor supply just so that I have an almost perfectly linear DC
    o 100μF
    o 16V

My wiring and soldering is on point everywhere, I have more than double-checked every connection, validated my schematics, validated my coding and insulated every exposed cable with thermosetting tubing. The driver is setup on a generic breadboard and all the connections between the components are made on it.

I’m lost and I don’t know where the problem could be coming from and I haven’t found an answer on the forum so that is why I’m contacting you today

I also would like to mention that for the setting of Vref (0.342V at 70% of the told amperage on my motor) on the driver it has been impossible for me to go further than a Vref of 0.350V

  • Is it normal for a driver that allows the monitoring of 2 A motors to be limited to a Vref of 0.350V ?
    I only have a multimeter if you want me to measure “something somewhere”
    I can also share the wiring via photo or image if you really need to but I really don’t think the problem comes from here

My wiring follows this plan: https://howtomechatronics.com/wp-content/uploads/2015/08/Controlling-Stepper-Motor-Circuit-Schematics.png

I am so sorry for the size of my post but I’ve already contacted the support of the website I buy most of my components on and they could help me so I’m spiraling into madness at the point of doubting if the driver isn’t counterfeit
Thank you for your time and your help if you have any


Links for the main components :
Moteur 17HM15-0904S - Moteurs pas-à-pas | GO TRONIC - motor
Driver de moteur pas-à-pas A4988 2128 Pololu - Commandes de moteurs pas-à-pas | GO TRONIC - driver
Adaptateur MV530N - Adaptateurs continus régulés | GO TRONIC - power source

Hello again !
I’m adding a picture my wiring just in case the problem might come from here
I’ve tried and written various codes so the Step and Dir pins are usually on 2 and 3 but i’ve moved the pair to other pins (just in case once again, also I’ve tried using several libraries but none worked)

Top left right/black wires are the before mentionned power source for my stepper
And for the 1A, 1B, 2A, 2B have been paired accordingly together

I also forgot to tell that I have no noise, movement or whatsoever

Thanks again for your time


Please note, our company name is Pololu, not “Polulu”.

Also, I moved your post to the “Motor controllers/drivers and motors” category since it is more appropriate there.

It sounds like you are using a 5V supply to power your A4988, but its minimum operating voltage is 8V, so you will need to supply at least 8V to the A4988 carrier for it to function properly.

By the way, it seems like you might be questioning whether your driver is genuine. The site you linked to for the driver is to one of our authorized distributors, and the top of the board looks like ours, so I think you can be fairly confident you have one of our boards. If you want to be absolutely sure though, you are also welcome to post a picture of the bottom of the board.

- Patrick

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Hello again
Thank you for your answer !

I’m so sorry for the mistype and posting in the wrong category, I will try to be more careful for the future !

Ok so it was that easy, I feel dumb lol
So if i keep the same motor:

  • should I upgrade my power supply to an 8V or more ?
  • or should I “downgrade” to a new driver such as the DRV8834

In my opinion I would go for the second choice because i’m scared of frying my 5.4V motor given that the driver is the one who limits the voltage at 8V but I still haven’t taken time to learn electronics properly so I might be very wrong

Thank you again for your answer


I’m posting the other side of the driver just in case, I had it reordered because the first one was damaged around the potentiometer

Either of your proposed approaches could be okay, but I would suggest the first, increasing the voltage of your supply, since that will help you get more power out of your stepper motor. As long as you properly configure the current limit on your driver you do not need to worry about powering your setup from a supply voltage greater than your stepper motor’s voltage rating. The first question-and-answer under the “FAQs” tab on the A4988’s product page has more information about that.

The driver in your picture is definitely one of ours.

- Patrick

Oh yeah right, thank you so much for your help !
Sorry again for the dumb questions with easy answers, I tried to stay on websites of my own language to avoid making errors but I missed out on so much !

I’ll try to post an update of my project on the right category to thank you for your time and patience you’ve shown with me :smiley: !

Thank you again Patrick !

1 Like