Pololu A4988POW - Problems with 5V Supply and VDD

Dear forum,

I recently purchased a Pololu A4988POW and a stepper motor Sanyo Denki 103H7123-5010.
I connected the driver as follows:

I additionally connected a little pushbutton to VDD and the other side to STEP and connected DIR to GND.
The motor is connected as follows:
Orange: 1A
Blue: 1B
Red: 2A
Yellow: 2B

With the motor connected, I supplied power to the driver. Upon pressing the button, nothing happened.
EDIT: Voltage reading at VDD was 1.5V, instead of 5V.
I then disconnected power and all connection to the driver and only reconnected the Motor Power.
When I supplied voltage, I got proper readings at 5V and 3.3V.

My questions are:

  1. Did supplying motor voltage (18V) without the motor connected destroyed the driver? (So far I have assumed that only disconnecting a motor from the driver when power is supplied to the driver, would damage the driver).

  2. Is the motor connected properly?

  3. I saw a couple of people connecting RESET with SLEEP (which are both inverted, right?). Is this necessary and if so, what’s the purpose of this?

  4. Could you give a order in which I should connected my second driver to prevent damage to it and to any driver in the future?
    My suggestion would be:
    A. Connect motor to driver
    B. Connect 5V with VDD
    C. Connect pushbutton to VDD and STEP-input pin (and probably with resistor (5k Ohm ?) from STEP-input pin to GND as well)
    D. Power Driver with necessary voltage and check voltages at 5V, VDD, REF, across 1A and 1B, across 2A and 2B
    E. Press button for step(s)

Any help is greatly appreciated!

Kind regards
Niels Göran

Hello, Niels.

We don’t call it an A4988POW, but from the picture is looks like you have a A4988 Stepper Motor Driver Carrier with Voltage Regulators which is Pololu item #1183.

No, I do not think that would have damaged the driver. Connecting or disconnecting the motor while power is applied would be bad though.

Assuming that this datasheet accurately describes your motor, then yes.

With this product, it is not necessary to connect RESET or SLEEP to anything.

Are you sure that your first driver is broken?

Regarding your steps for setting up the second driver: Don’t forget to set the current limit to something appropriate by turning the potentiometer, as described here. Yes, a resistor between STEP and GND would be needed and 5 kilohms would be fine. Don’t forget to connect the DIR input to GND or VDD; otherwise it will be a floating input.

Please let me know if you have any questions!