A4983 problems


I am trying to build a stepper controller and driver unit using the A4983 Stepper Motor Driver Carrier with Voltage Regulators, but there are several things I’m not sure about and cannot find any information on. sorry - I have some electronics knowledge but this is all a bit new.

First, is there a clear picture anywhere of this unit wired up? I had the same problem as other posters of the motor moving by itself, then grounded the step pin through a 100K and it stopped moving, but it still makes a humming sound - is that normal? I have checked the amp limit to 0.9A using the method shown on the web page (the motor is a nanotec ST5709S1208 and is rated to >1A).

To try to fix this ‘hum’ I have either pulled up or down, according to the A4983 data sheet, the dir, reset, sleep and enable inputs, but I still get the humming sound when power is conncected. I have not built my controller yet - it will be a crystal controlled 4060 output, so I can’t test it with step pulses yet.

Also I’m not clear as to how the MS1-3 pins should be made high or low - can they be wired directly together and to VDD? The A4983 shows 100k resistors hsould be used, but the Pololu units says it has 100k resistors already?

So, is the ‘hum’ normal and do I need to pull up or down all the inputs or can any be left open? Does anyone have a picture of exactly how the inputs should be set?

Thanks for any help - I’m a bit worried about fusing something…


just wanted to clarify - I need the motors to run then power off - they do not need to hold because they will be on the worm drives of a telescope.


Are you using the A4983 carrier with voltage regulators(1202), or without(1201)? Either way, the product pages (1201, 1202) have good starting wiring diagrams. The product pages also have a table and a schematic that answer your questions about what to do with the micro-step selector pins.

Stepper motor can typically make some noise while turning or holding a position. If you don’t need it to hold a position, you can pull the NOT ENABLE pin high to disable the output FETs while you don’t need them.

Let me know if you have additional questions not answered by the product page.

- Ryan

Thanks, I had read the product page. I’m using the WITH regulators, which there doesn’t seem to be as much information about.

sorry - I’ll try to make my questions clearer:

-Do I need to connect MS1,2 and 3 together through a 100k to VDD or should they each have a 100K or should they connect directly to VDD?

-Why is SLEEP connected to RESET in some diagrams but not others (e.g.1201 Vs 1202)?

-Exactly how do I inactivate motors (no power) when not stepping? What connection to which pins do I need? I do not want them to hold.

Thanks again,


  1. If you don’t care about what microstep mode to use, you don’t have to connect anything to MS1, MS2, or MS3. The default is full-step mode.
  2. On the 1202, there is a pull-up resistor between NOT RESET and VDD. The 1201 doesn’t have a pull-up resistor there; connecting it to NOT SLEEP takes advantage of the pull-up resistor between NOT SLEEP and VDD.
  3. There isn’t a feature or wiring that passively supports what you want to do. Whatever is generating the STEP inputs needs to be able to pull the NOT ENABLE line high when it is not stepping.

- Ryan

ok, I think I have it now.

-I don’t need to connect sleep to reset (it is called reset on the diagrams)

-I need to ‘pull’ ‘not enable’ (its called enable on the diags) to VDD through 100k when I am not stepping

-I do need to use 1/16th microstepping, so I need to connect MS1,2 and 3 to VDD

(best not to mention the 1201 in answers, because I’m not using it - I’ll get confused!)

Hope that’s right, thanks.

I’m using a 4060 with a 100KHz crystal for the step signal. At pin 2 it should give me the 12 Hz signal I need. but that’s another story…


All of that looks correct except that you would need to use a stronger pull-up than 100k to pull up NOT ENABLE because there is a 100k pulldown on NOT ENABLE. You can connect it directly to VDD instead of using a pull-up resistor.

The bar over the pin names on the diagram indicates the negation of the pin name (ENBALE becomes NOT ENABLE, etc.). Following the convention that a high voltage on the input will have the effect of the name of the pin, a high voltage on the NOT ENABLE pin will disable something. A high voltage on the NOT RESET pin will not reset the chip.

- Ryan

Thanks very much, its working now.