a4983 setup

I recently purchased the A4983 board and have been trying to get it working with a small stepper. Sending 5v pulses on the step pin(@ approx. .1 sec) results in no action from the motor.

First of all, My connections:
VDD -> 5V
5V -> not connected
3V3 -> not connected
Vmot -> 12V
Dir -> Gnd
Step-> 5V pulse input from AVR
MS1,2,3 -> GND (full step)
Ref -> adjust this to .20 V
SLP -> 10K pullup to +5
RST -> 10K pullup to +7
Out1B,1A,2A,2B - to stepper windings


  1. Approx. 0 voltage on all of motor windings.
  2. SLP and RST measure close to ground, even with pull-up resistors.

My questions.

  1. Should I see some voltage on motor windings?
  2. It worries me that SLP and RST appear to be forced to GND. The schematic shows them with 100K pull-ups to VDD, so I expect +5V. Is there something I don’t understand about hooking up VDD to an external logic source and that voltage getting to the pull-ups?
  3. Can anyone suggest other trouble shooting tips to get this working? I don’t believe I’ve done anything to kill the chip but is there a way to verify this?
  4. Do I need to a reset sequence?

Thanks for any help


First off, there is not a “the” A4983 board; it sounds like you have this version with built-in regulators. Why don’t you want to use the built-in regulators if you got that version? That said, you should be able to connect the Vdd line to your own 5V supply. The !sleep and !reset lines being held low is troubling, and that would account for no output even if everything else were working. You don’t have ground explicitly listed in your connections list; you do have them all connected, right? There is no reset sequence. Have you verified that your 5V supply is good? Does the board work if you use the internal 5V supply?

- Jan

I have been having trouble with the same board (non voltage regulator version) connected almost same way (i have SLP and RST tied to each other as suggested elsewhere) but to an arduino decimila. I got a high pitched sound when it was connected to power so i have disconnected it, before i blunder on and burn something out.

Edit: forgot the important thing to mention that my stepper locks off while making the sound as well, i originally thought this was due to incorrect connection of the stepper but i have verified correct connections

By the way, it sounded like the original poster has the version with regulators, so that is not the same board.

Anyway, where was the sound coming from? If it was from the motor, it’s possible you were just trying to step faster than it could. What do you mean by “my stepper locks off”? What is your power source? is the sound coming from there?

- Jan

Um well I’m stepping The dir pin high for .5 second low for .5 second. So that should be plenty slow the sound seems to be coming from the board. And the motor locking off is as if it is provideing power to the coils stoping you from turning the stepper shaft. Lastly I am powering with a 12v 2A wall plug but will be controling the final project useing an old pc power supply I have.

There’s not much on the board to make noise, but capacitors can vibrate a bit if the voltage on them changes. Do you have an oscilloscope you can use to look at various signal and power lines? I suspect your power supply might have really big fluctuations as the motor driver turns the current on and off.

- Jan

I will have a go latter today with the pc power supply and see if it functions, i just figured that it would be safer to test things with the lower amperage one first (it is a wall wart that was originally from an external HDD (the small kind so i assume it is a switching one)), about the capacitor vibrating, i find the sound stops if u put a finger on the pot (which if im correct is a resistor not a capacitor).

Yes, the pot is a resistor, and that is very unlikely to be the source of the vibrations.

- Jan

Finaly got it figured out, turned out to be a silly problem with a mispelt variable name that resulted in the step size pin being left floating, its still making the noise but it is quieter now. Thanks for being helpful, is it worth worrying about the noise its making

It depends on what you’re doing. If some failure down the road will cost you a lot, it’s worth looking into. It’s also a function of how easy it is for you to do the extra evaluation: if you have a decent scope available, you should take a few minutes to try to figure out what the problem is.

- Jan