L298N and L297 for stepper motor (unipolar)

[same79]

Hi,
I want to build a circuit for my stepper motor (unipolar) using L298N and L297 as shown in subsequent attached circuit diagram. I believe it is for stepper motor (bipolar) since there is not any symbol to join stepper motor common wire. Please lead me how I can make use of this circuit diagram for stepper motor (unipolar).
My stepper motor (unipolar) is this

[BackyardWorkshop]

I had a little success with an L298, a unipolar stepper, and a Parallax Propeller - I don't have how I wired it here at work, but when I get home I can get that for you - but here's a video I made showing it

Backyard Workshop - Parallax Propeller Stepper Motor Driver

Jamie

[marzetti]

Check out this site for 297 unipolar driver: PMinMO.com

[BackyardWorkshop]

Looks like they have a problem with their site - some MySQL error

[irving2008]

The L298 is a bipolar driver... you can make it work with a unipolar motor by ignoring the centre tap connection on the coils and just using the ends. The performance you will get compared to a proper unipolar driver will be reduced because the coil inductance is quadrupled and the coil resistance doubled therefore the torque drop off with speed will be much higher. But that might be ok for your application.

[same79]

I apply the pulses as keeping Enable to 1 and Clock to 1 & 0 again & again to move the step. But it did not. Why? What is batter way to issue pulses from parallel port?

[irving2008]

I apply the pulses as keeping Enable to 1 and Clock to 1 & 0 again & again to move the step. But it did not. Why? What is batter way to issue pulses from parallel port?

Have you used the circuit you attached above?

[same79]

Yes I am using above attached circuit.

[irving2008]

Yes I am using above attached circuit.

That circuit is incomplete, What have you done with Vref, Control, Reset inputs and what values are you using for RS1, RS2?

[same79]

I am only applying the pulses to Enable to 1 to keeping circuit switch-on and Clock to 1 & 0 again & again to move the steps, and all other Vref, Half/Full, Reset, CW/CCW, Control,Sync,Home are open(means not any pulse to them). And I am using 0.5 ohm 2W, resistor for RS1 & RS2.

[irving2008]

You need to read the L297 and L298 datasheets to understand how these chips work.

As a minimum Control needs to be grounded (0v), Half/Full needs to be pulled to +5v for Full step or 0v for half step, it is not safe to leave floating because of noise from the motor. The direction input CW/CCW needs to be driven, again it is not safe to leave it floating. Reset needs to be pulled up to 5v via a 1K resistor and a 1nF capacitor to 0v, leaving it floating will cause erratic operation. Home and Sync should be left unconnected.

Vref needs to be set to a voltage that is 0.5 x the motor current you want to set. so for a 1A motor, vref must be 0.5v, best provided by a voltage divider off the 5v rail...

For a more complete and known good circuit (I use this one myself) see PMINMO's site here


What motors are you using? the link you gave before does not work...

[irving2008]

OK, i just found the motor you are using... the correct link is this

I'm sorry my friend but those motors are not going to work with this circuit... for several reasons...

Firstly these are 5-wire motors and you can only use the suggestion I made before with 6-wire unipolar motors.

Even if they were 6-wire they are not going to produce any useful torque. They are 24v motors, designed to be driven directly from a 24v supply, so two phases together driven bipolar on a 36v supply will limit the phase current to such an extent you will get maybe 1/4 of the torque available. And as these motors are designed for the paper-feed on a HP printer, so they are very low torque to start with (pushing a sheet of A4 isn't exactly hard work).

If you wish to carry on with those motors then dont use the L298 but follow this circuit instead, L297 Unipolar, also off the PMINMO site.