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A3977: strange behavior

  • Thread starter Marco Trapanese
  • Start date
M

Marco Trapanese

Jan 1, 1970
0
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
 
M

Marco Trapanese

Jan 1, 1970
0
Marco said:
What could I do to focus the cause?

Change the chip wasn't enough. I had to change it twice...

Marco / iw2nzm
 
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