Stepper motor just vibrates in CCW

[toomy]

I have a 5-wire unipolar J835L. I have not been able to find the datasheet on it, but I have found this diagram:

also, the motor has the following information printed on its label:

Uni-Polar, Bi-Filar
120 Ohms
7.5° per step

I have connected a ULN2003A between the uC and the motor
where i connect the wires purple, blue, yellow then orange

I drove the circuit in order
1 00000001
2 00000100
3 00000010
4 00001000
and than return back again
I set each step and then wait for 100ms

this was working successfully but when i tried to reverse the rotation so it rotate in CCw the motor just vibrate and do not move as the CW .
Can anyone give me a pointer?

regards
toomy

 

[Fish4Fun]

toomy,

Shortcut for finding the proper wiring sequence

Connect the center tap(s) to the power source (or current-Limiting resistor.) Connect the remaining 4 wires in any pattern. If it doesn't work, you only need try these 2 swaps...

1 2 4 8 - (arbitrary first wiring order)
1 2 8 4 - switch end pair
1 8 2 4 - switch middle pair

You're finished when the motor turns smoothly in either direction. If the motor turns in the opposite direction from desired, reverse the wires so that ABCD would become DCBA.

taken from: http://www.stepperworld.com/Tutorials/pgUnipolarTutorial.htm

You might give that a try. You might also go to the link for a very good tutorial.

Fish

 

[toomy]

thank you fish
I tried your suggest but it is not working

However, I found the correct way to run it
it just have to wait the other switches so it rotate correctly
1 00001000
2 00001010
3 00000010
4 00000110
5 00000100
6 00000101
7 00000001

 

[schip666!]

Without trying to reverse engineer this whole thread ... Your last pattern looks like it does half-step operation, whereas the original pattern is simple full-step. Half-step gives a little extra boost to the output torque because (half the time) it energizes two coils. So maybe your motor is sticky in one direction for some reason?

Otherwise I think you still have the wrong wiring sequence. I usually just do an exhaustive search by powering each coil by hand -- briefly connect two wires from the power-supply to each coil and see what the motor does. Then check a few sequences, if the motor jerks back and forth you have the wrong sequence but if it moves in one direction without hesitation you've probably discovered the right sequence. Once you've got one right sequence, just reversing that order should go the other direction. I haven't tried Fish's test protocol but it sounds like it's an logical minimization of my brute force methodology and it should work.

If you have another motor, give it a try to see if it behaves the same.