The only disadvantage is that you need a bipolar driver circuit (more complex than unipolar)
An advantage is that you use all of the winding, not just half, so efficiency is better.
I think there is a misunderstanding between bipolar and unipolar - I meight be wrong, but as I have understood the output of my stepper research a bipolar stepper has 4 wires a and a unipolar stepper has 6 wires... So a unipolar stepper can also be used as a bipolar stepper by skipping the two middle coils...
The motor specs of my stepper tell that in unipolar mode the stepper takes 1A and in bipolar mode 0,7A... So I guess efficiency in unipolar mode (6 wires must be better)...
I want to bring up the efficiency as high as possible, so I am still interested in how to drive that thing in unipolar mode.
The question is, if the Arduino Motor Shield R3 is also capable of driving a stepper in unipolar mode without attaching additional hardware, and if how?
No effect upon steps/rev, and yes just ignore the centre-taps. Make sure the wires from one
winding go to A+/A- and from the other to B+/B-.
You are right. Yesterday I have tested it.
My stepper has 200 steps for one revulution - if I let it turn 200 steps, it moves back to the position it had been.
Do you know the ratings of the motor? Current and winding resistance?
unipolar mode: 1A
bipolar mode: 0,7A
resistance: 3,6Ohm
force: 27Ncm
I have discouvered another thing:
Actually in my hardware settup I am using an arduino due with a ethernet shild (I am just using the SD-Card from the ethernet shild) and two of the motor shilds, which I attached as side wagons.
First I am transmitting data (coordinates) over the serial interface and write it to the SD-Card - Then the two steppers are fed with the data on the SD-Card till the file is finished.
Well when just one stepper turns and the other shall stand still - one led of the stand still stepper is also kind of flashing (the stand still stepper does not turn, it is more like a slight vibration) - I think this is caused trough feedback Voltage from the turning stepper... Is there a easy way to avoid this feedback voltage phenomena? I thaught of using optocoppler to seperate the engines from the bord...
Thx,
Andreas