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Crazy stepper driver

Crazy stepper driver

Postby funtasma » Thu Jan 14, 2010 9:27 pm

I'm just testing the Markus Mechatronics stepper motor driver card but it reacts different from what I expected.

1. The motor is turning permanently without giving any signal. The speed is changing when I switch the three micro switches.

2. When I fire a stepping signal the motor stops as long as the signal continues. Afterwards the motor starts running again.

3. And now it comes to real madness: When I disconnect the stepping/direction cables and take just a short piece of wire, I can change the direction of the running motor in quasi magic way. I just need to get close to the stepping signal connector and the direction and speed of the motor changes. Just like with a radio control.

What is going on here? Did I kill the controler chip while assembling the card?
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Re: Crazy stepper driver

Postby WalterMo » Thu Jan 14, 2010 10:45 pm

Hello Benjamin,
Don't worry, the board is highly probably not killed.

All its inputs are high impedance ones. That means if you connect an open-end wire at them this wire acts as an antenna and forces the chip to do arbitrary functions. Therefore connect the DIR (direction) input to +5V or to 0V (Gnd) or to an output of another IC.
The STP (step) input to the output of a 5V clock generator. And don't forget the Gnd line between generator and driver board.
And let all the other inputs for first tests untouched (without open-ended cables).

The speed is of course changing when you switch the micro switches. The position constellation of switch "2" and "3" defines the kind of the micro stepping mode. E.g. in full step mode the motor turns eight times faster than in 1/8 step mode because the step width is eight times wider.
Micro switch „1“ enables all functions and must therefore switched „ON“. That means it connects then Pin 3 of the chip to Gnd.

But if nothing helps, you can send the board to me and I will check it.

Walter


P.S.: The EasyDriver will show the same behavior.
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Re: Crazy stepper driver

Postby funtasma » Fri Jan 15, 2010 1:36 pm

Walter, you're right. Thanks once more! I really appreciate that.
I wanted to test the card manually, before connecting it to my USB-board, but it delivered the result above.
Running the driver card with the USB-board works great - no problems anymore. So I can finally go on building the next generation of my laser scanner.

-Benjamin-
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