Stepper Motor - Big Easy Driver

I am trying to get a stepper motor running so that I can use it to control a butterfly valve in an air duct.

I am using;

Arduino Uno clone
Big Easy Driver
12v to 10v buck converter (this will eventually be in a car so the buck converter will smooth the power)
12v to 5v buck converter to power the Arduino
Polou stepper motor

I have followed the BED guide. When I turn on the power both buck converter output 5v and 10v respectively. The LED on the BED lights. The stepper motor makes a high pitch squeel but does not move. Sometimes I here what sound like the stepper motor stepping but it is not moving (I have checked that the motor is correctly connected to the butterfly flap).

I am using the stepper motor as a 4 wire not a six with the white and yellow motor wires not used.

The Arduino code (attached zip) I am using is VERY basic and is designed just to move the stepper to test it. The wiring is attached in the fritzing file.

Have I just got something wrong or could I have a bad driver board? (502 Bytes)

Have you wired in the RST, Sleep and Vcc pins on the Big easy board?

  • RST : Logic Input. When set LOW, all STEP commands are ignored and all FET functionality is turned off. The translator is set to the Home state as well. This must be set HIGH to enable functionality of the motor driver.
  • SLEEP : Logic Input. When set to LOW, the A4988 enters sleep mode, and disables functionality of the FETs, internal current regulator and charge pump. When switching this pin to HIGH to wake up the IC, allow 1 ms of delay before sending a STEP signal. The IC will return the motor to the starting position upon receiving a HIGH signal on this pin.
  • VCC : Logic Supply.

No, no and no! The Big Easy Driver hookup guide did not show them connected.

Vcc - is this the supply into the BED or a supply out to the Arduino (5v or 3.3v depending on how the BED jumpers are configured)?? My Arduino is powered from a separate 5v supply as shown in my diagram.

EDIT: it now works. I think I have a faulty power cable from my 10v buck to the BED. Replaced the wire and the butterfly valve now spins. How annoying. Many thanks for your input.

1 Like

Great to hear you got it working! Faulty cables is about 90% of the fun in prototyping electronics :slight_smile: