Hi,
I'm puzzling over a board with an A3977 to drives a bipolar stepper. I made connections as the datasheet says.
When I apply an high frequency square wave on the step input the motor will run fine, maybe it forgets some steps at then begin (due to the too high frequency). Instead, using a very low frequency - such as step-by-step - the motor doesn't work. It rotates few steps (2 if in half step mode, 4 in quarter and 8 in eighth) and then return to the initial position.
It seems an error on the connection of the phases. However, I don't understand why it works with a high frequency signal. I've checked wirings a half dozen of times and seems to be right....
What could I do to focus the cause?
Marco / iw2nzm