Stepper Motor jitters and takes steps in wrong direction

hello,

i got stepper motor work using olimex bb-a4983 driver, arduino uno , bipolar stepper motor (polulu 1207).

i going using motor small load , @ slow speeds, need precise (not high resolution though, 200 steps per revolution fine) can't have skipping steps.

anyways have wired ok , motor turning, behaving strangly.
every 3 or 5 steps jitter, or take few steps forward or backward.

what cause of ?

here video of problem.

i tried half-stepping didn't change anything

here code in case

const int steppin = 3;
const int dirpin = 4;
const int sleeppin = 2;

void setup() {
  pinmode(sleeppin,output);
  pinmode(halfsteppin,output);
  serial.begin(9600);
    digitalwrite(dirpin, high);
}

void loop() {
  digitalwrite(sleeppin, high);
  (int i=0; <= 100; i++){
    digitalwrite(steppin, low);
    delay(1);
    digitalwrite(steppin, high);
    delay(1000);   
  }
}

it power supply problem. post wiring diagram , describe motor power supply.

Arduino Forum > Using Arduino > Motors, Mechanics, and Power (Moderator: fabioc84) > Stepper Motor jitters and takes steps in wrong direction

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