small stepper & accelstepper lib

[system]

hi,

ive started to experiment with the accelstepper lib. But i cant really get my motor running with it, or it runs but in strange a vibrating phase.
the motor i use is Small Stepper Motor - ROB-10551 - SparkFun Electronics and these are the specifications:
— cut from a forum post "Stride angle =7.5 Max no idle PPS (assuming pulses per second)=1600
1600 pulses per second* 60 seconds in a minute * (7.5 degrees per pulse/ 360 degrees per revolution) = 2000 RPM"

Im using the Pololu - A4988 Stepper Motor Driver Carrier to drive the motor.
I have attached an image of my circuit, i feed the stepper with 12v
I found out (with a meter) that the yellow and orange cables on the motor are 'connected' same goes for black and brown.

#include <AccelStepper.h>

AccelStepper stepper(1, 9, 8); // pin 9 = step, pin 8 = direction

void setup() {
  stepper.setMaxSpeed(200);
  stepper.setSpeed(100);
}

void loop() {  
   stepper.runSpeed();
}

[system]

gerbsi:
cant really get my motor running with it, or it runs but in strange a vibrating phase.

You would need to get the four motor connections in the right order. If it isn't working, it may be that one of the coils is reversed - try arbitrarily swapping over the connections to one coil and see if that makes a difference? If it's no better, you can always change it back.

[Grumpy_Mike]

The other thing is to try the motor at a much slower speed, say five RPM and if that works see how fast it will go before stopping.

[system]

Thanks,

ive tried some swapping — it became worse.
could it be the configuration of the motor?
http://www.pjrc.com/teensy/td_libs_AccelStepper.html

to run it in a slower rpm id set the

  stepper.setSpeed(100);

to a lower number?

[system]

I just fount this description about step resolution; since im not writing low to 'MS1' 'MS2' 'MS3' perhaps the motor tries to do 'Sixteenth step' which causes the strange behaviour!?
illa attacha an image.

cut from pololu
"Step (and microstep) size
Stepper motors typically have a step size specification (e.g. 1.8° or 200 steps per revolution), which applies to full steps. A microstepping driver such as the A4988 allows higher resolutions by allowing intermediate step locations, which are achieved by energizing the coils with intermediate current levels. For instance, driving a motor in quarter-step mode will give the 200-step-per-revolution motor 800 microsteps per revolution by using four different current levels.

The resolution (step size) selector inputs (MS1, MS2, and MS3) enable selection from the five step resolutions according to the table below. MS1 and MS3 have internal 100k? pull-down resistors and MS2 has an internal 50k? pull-down resistor, so leaving these three microstep selection pins disconnected results in full-step mode. For the microstep modes to function correctly, the current limit must be set low enough (see below) so that current limiting gets engaged. Otherwise, the intermediate current levels will not be correctly maintained, and the motor will skip microsteps."

[Grumpy_Mike]

I have just had a look at the Accel library and I don't think it supports drivers like the one you have. From what I can see it just supports:-

This defines a single 2 or 4 pin stepper motor, or stepper moter with fdriver chip,

http://www.open.com.au/mikem/arduino/AccelStepper/classAccelStepper.html

So unless your driver is classed as a fdriver chip you will have to write the software your self. This is of course almost trivial. Just set the direction to one state and pulse the step pin as you would a blinking LED. See if that makes it move.

As to the micro stepping, you don't at this stage want it so leave the inputs alone.