Hi,
Iam using NMB-MAT PM35S-048-FEEE6 motor, i have used ULN2003a to drive the motor by giving the sequence using a p89v51rd2fn micro-controller. when i gave 12V to uln2003 it got burnt so now m using 5V VCC to it.
The problem is, the motor is rotating only 4 steps and again coming to the starting point.
i have given the sequence in a for while loop. ie while(1)
ULN2803 can drive unipolar stepper motors, I suggest using L298 H-Bridge drivers for bipolar stepper motors.
you can using links attached to this posts for more information.
Stick a current limiting resistor in series with each winding. "clock" the motor one step at a time and measure the voltage on each coil, you should then be able to determine if two windings are being energised at the same time. Or just use high impedance loads directly on the output of the micro, to check that the code is correct.
Frank