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### Topic: 2 Easydriver questions (Read 1 time)previous topic - next topic

#### brianhockenstein

##### Apr 10, 2011, 08:03 pm
Hello,

I have some low level experience building stepper motor based timelapse systems for photo and video work but just recently got my hands on the EasyDriver 4.4 board and am stoked with how simple it is to use and set up. I do have it running and basically doing what I want but am a bit confused on how to adjust a few elements.

My two questions are

The potentiometer on the EasyDriver board does not seem to affect the speed the motor is moving at. It doesn't seem to do anything at all really. Am I wrong in that I thought this is how you adjust the speed of the motor? What is going on?

Is there a simple explanation on how to write the sketch to move a stepper motor with the EasyDriver board anywhere? Referencing the Portugese tutorial that everyone points to, I do have it moving and can figure out a few things but am basically lost in the programming. The only real things I care about is how much it moves, the delay between moves, and adjusting the speed of the motor...

BH

#### MarkT

#1
##### Apr 11, 2011, 01:59 am
The pot controls the current to the motor.  For stepper motors the current has to be large enough to overcome the physical resistance and small enough not to overload the motor.  Stepper motors have a rated current - this is usually the max current for one winding being driven by itself.  Do not exceed this - the motor will overheat.  That's _will_ overheat - the maximum current is really the maximum heating the motor can take.

Typically you can run a stepper at a lower current than its rated current - unless you need all the torque it can give, but it depends on your mechanical set-up.

Secondly driving the easy driver is conceptually very simple - set the direction pin, clock the step pin.

However you need to time those steps and be aware of velocity and acceleration - look around for stepper libraries, I think there's one called AccelStepper that might do useful stuff - otherwise you can roll your own using delayMicroseconds() or micros().
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

#2

#### brianhockenstein

#3
##### Apr 16, 2011, 08:51 pm
Thank you for your reply. I have seen this tutorial although I am still at a loss as to how to control the speed/RPMs of the motor

#### marzetti

#4
##### Apr 16, 2011, 10:05 pm
The speed of the motor is a function of the step rate. For instance if your motor has 200 steps per revolution, in full-step mode 200 steps/second will drive the motor at 60 rpm. Half-step mode will give you 30 rpm, quarter-step mode will give you 15, etc.

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