# Help understanding pins on a stepper motor driver

Hi I need to controls some steppers for a work project. I found this driver in the back and can't find a data sheet online. My main question is what are the out pins for? The rest seems straightforward but correct me if I'm wrong. I'm controlling with a raspberry pi and I'll attach gpio to all the enable step and dir. Then I can send out pulses to step plus while enable + is high and changing direction+ will change the direction.

• Does that answer your question? If you want positive logic , ground cathode and drive Anode Commented Mar 13, 2018 at 23:16

I remember I had two similar ones in my garage , also without a manual.

I would expect this, but you can measure current with a 220 Ohm R to 5V to verify what the internal R is, if any.

The opto inputs allow you choose polarity of driver from Logic or an open collector comparator. Arduino outputs can drive this.

You need step pulse 1~10us min. up to 100KHz? depending on microstep resolution. Direction and Enable. Out you can check if that is active with a DMM or needs a pullup to Vcc.

simulate this circuit – Schematic created using CircuitLab

SW4 may be the holding current after step which might be cooler at 50%.

400 Step will give max acceleration, torque and RPM at constant step rate. Bigger is smoother and quieter but less torque. You accelerate step rate during seek for max. velocity without cogging/slipping, according to load and adjust current accordingly with average power, holding current,SW4?? with Pd and temp rise of motor. Keep warm not hot.

• THis does not answer the question of the function of the OUT connection. Commented Mar 13, 2018 at 14:57
• True but he can measure it with a pullup treating is as a floating opto open-collector and see if it is useful for diagnostics or operation. My crystal ball is fuzzy before 2 cups of coffee. I'll let you answer this. A really useful Out would be current pulse. Commented Mar 13, 2018 at 15:22
• Ya I have no idea what it is either. Feedback would by my guess too but who knows. Can't even tell if it is an input or an output. Commented Mar 13, 2018 at 15:45
• Since it has intelligent LED code diagnostics, I would expect OUT with some serial code akin to the LED's 2 RD pulse and 4 GR pulse. Commented Mar 13, 2018 at 16:09
• That would be a nice feature... but who knows. Commented Mar 13, 2018 at 16:10