A4988 Micro Stepper Driver and AccelStepper

Support Motor controllers/drivers and motors
1

Problem:

I have a 2 wheel driven differential drive for my robot. True straight line accuracy is not good enough without encoder feedback to the DC motors, but simple Accel/Decel Control and Progressive Steering changes are easy to achieve.

Option:

I would like to change to Stepper motor drives using the Allegro A4984: DMOS Microstepping Driver with Translator and Overcurrent Protection and the AcccelStepper library for the Arduino micro controller, using microstepping at the 8 microstep level.

Questions:

  1. Without the purchase (yet) of the Pololu A4988 micro stepper driver carrier and 12V~ 2A (+/-) steppers – does anyone know how well the Pololu driver carrier interfaces to the AccelStepper library ?

  2. The step frequency limit at 4K/sec is OK, does any one have experience of the frame noise of either NEMA 17 or 23 steppers when running between 0 → 3K steps/sec ? Clearly some resonance bands will exist, but at what frequencies might they occurr for these frame sizes at the chosen microstep level.

Tx Rob

2

Hello, Rob.

Stepper motors tend to have too little torque to be used as the drive of a robot. I recommend making sure you have the torque you need before going to far down this path.

Here are my answers to your questions:

  1. I haven’t tried using AccelStepper before. I looked at the source code and documentation for the AccelStepper and it appears to support stepper motor drivers with step and direction pins, if you set the first argument of the constructor to 1. So, there is a good chance it will work with the A4988.

  2. Sorry, I don’t know what frame noise is, and I don’t have experience with resonant frequencies of stepper motors.

- Ryan

3

I have used polulu a4988 with accelstepper it works fine with full step mode

4

Is there any difference in the attained torque for different MotorInterface types for A4988 used along with AccelStepper?

I am using simple STEP/DIR pins and type 1 (DRIVER) mode. Can I get better torque if I use FULL4WIRE mode? If yes, what is the pinout configuration on Arduino/4988 side?

5

Dear friend,
You can not use the full4wire mode with a4988, you can use appropriate
speed for required torque.

6

Thank you,

In the AccelStepper library, in examples directory there is a sample script called ConstantSpeed, which uses FULL4WIRE mode; but now I understand it is not intended for A4988. Then will microstepping give better torque or not? I read mixed statements about microstepping where in general microstepping gives better control but less torque: Is this valid for A4988?