Power Supply & Amperage - Confirmation of understanding

Hello good people,

This is my first foray into stepper motors. The hardware I'm working with:

My questions/research:

  1. I have read that it is recommended to use an un-regulated power supply and that switch-mode regulated supplies can often fold voltage to protect itself as it can see the instantaneous current as a short
    True or False? Should I be concerned?

  2. The highest RMS current setting on the DM556T is 4.0A (Peak 5.6). With normal DC motors I wouldn't generally worry, but as steppers operate a little differently I'm not certain how much of an impact 0.2A will have - I assume it'll just be a hit to torque and nothing else?

  3. If my motor needs 4.2A/phase, we can multiply that by 1.4 to get the "general" load of 5.88 (lets say 6A)
    Am I pushing it with my 24V, 6A supply at this stage?

Thank you in advance

I have the following circuit to drive a stepper motor, see below:

It was adapted from this - I just got rid of the switch and pot to make it simpler.

I have the following code:

int driverPUL = 7;
int driverDIR = 6;

void setup(){
pinMode(driverPUL, OUTPUT);
pinMode(driverDIR, OUTPUT); //not used
}

void loop(){
pulseDelay = 2000;
digitalWrite(driverPUL, HIGH)
delayMicroseconds(pulseDelay)
digitalWrite(driverPUL, LOW)
delayMicroseconds(pulseDelay)
}

However the motor doesn't turn, I've checked with a multimeter and the PUL+ measures 5V while PUL- measures 2.5V

Not quite sure what the issue is..

Thanks in advance!

The setup() part of your sketch is missing. You have to set your PUL and DIR pins to OUTPUT mode there.

Sincere apologies, not sure why I excluded that.

Have updated the original post to include the setup method.

Hi, @gengee

It doesn't compile, how did you get it to upload?

Can you please tell us your electronics, programming, arduino, hardware experience?

Tom... :smiley: :+1: :coffee: :australia:

Hi @TomGeorge, yes, apolgies I have updated the original post. I'm a software engineer, have previously worked in industrial settings ie with PLCs, ok with basic RLC circuits, first time playing with micro controllers.

You need a 24V power supply connected to the microstep driver.

PLEASE don't update old posts, it disrupts the flow of the thread and makes it confusing to anyone who reads this to help with a problem they have.

Your update, still will not compile.

Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?
Hand drawn and photographed is perfectly acceptable.
Please include ALL hardware, power supplies, component names and pin labels.
Thanks but Fritzy images are not comprehensive enough.

Tom... :smiley: :+1: :coffee: :australia:

1 Like

POWER?

Yes, a 24V, 6A supply is connected. I will provide a comprehensive schematic as requested by Tom soon.

Ok, so:

Hardware:

Schematic (I hope my artwork cuts the mustard..):

Verification of Driver setup:


Do you have the DM556T set for 2.7A and 200 steps?

No, I've got it set to 3.5A and 800 steps.

And here is the full code that compiles:

// DECLARE PINS
int reverseSwitch = 2; //not used
int driverPUL = 7;
int driverDIR = 6;
int spd = A0; // not used

// VARIABLES
int pd = 500;
boolean setdir = LOW;



void revmotor(){
  setdir = !setdir;
}

void setup() {
  pinMode (driverPUL, OUTPUT);
  pinMode (driverDIR, OUTPUT);
  attachInterrupt(digitalPinToInterrupt(reverseSwitch), revmotor, FALLING);
}

void loop() {
  pd = 2000;
  digitalWrite(driverPUL,HIGH);
  delayMicroseconds(pd);
  digitalWrite(driverPUL,LOW);
  delayMicroseconds(pd);

}
-Sketch uses 1026 bytes.

'not used' is not true - you assigned an interrupt to it. How did you wire that pin? if it is left open it can receive interference and it may trigger your interrupt.

1 Like

Comment out the attachInterrupt and see if it works

1 Like

Ah, ok.. I didn't wire it in. Remove and try again

No luck, I have also dropped the steps down to 200.

Are you sure the stepper motor itself is wired to the driver correctly?

That sounds correct, a 50% duty cycle pulse would read as roughly 1/2 Vcc on a voltmeter DC scale.

1 Like

Do you have the 5V/24V switch at the top of the DM556T set to 5V?

This is the card that came with the motor:

My wiring:

@jim-p Driver voltage is set to 24V