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DRV8825 STEP pulse width question

Hi,
I am having difficulty with this driver needing longer than expected STEP pulse width. I’m using this http://www.stepperonline.com/gear-711-planetary-gearbox-for-nema-17-geared-stepper-motor-p-45.html rated at 1.68A per phase. I have the current limit pot set for 1.4 amp (12V supply) as measured in series w/ the stepper while not stepping (I will only use full step mode)…increasing to 1.7 amps does not change anything.

I find that the minimum STEP pulse width is about 400us (from arduino). Anything lower the motor just buzzes. Load doesn’t seem to matter either. Sorry if I’m missing something obvious…can’t figure it out

Thank you!
kevin

Here’s my arduino code (pin 2 to STEP, pin 4 pushbutton switch to activate, 3 will be direction, 13 LED

[code]void setup(){
pinMode (2, OUTPUT);
pinMode (3, OUTPUT);
pinMode (4,INPUT);
digitalWrite(4, HIGH);
digitalWrite(2, LOW);
digitalWrite(3,LOW);
pinMode(13,OUTPUT);
digitalWrite(13,LOW);
}

void loop() {
while (digitalRead(4) == LOW){
delayMicroseconds(400);
digitalWrite(2, HIGH);
digitalWrite(13, HIGH);
delayMicroseconds(400);
digitalWrite(2, LOW);
digitalWrite(13,LOW);

}
}[/code]

Hello.

It sounds like you are being limited by your stepper motor at this point, not the driver (basically, your stepper motor’s rotor physically cannot keep up with the rotating field). The following forum threads have a few tips for maximizing the rotation speed of a stepper motor:


- Ben

that makes sense…I’ll play with it.
thank you!
Kevin