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MC3479

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zhizhi

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I just got this Stepper motor driver chip... I have gotten the datasheet.. how ever i have some querries...

Does anyone know how to i get more information to hook this up with my PIC16F877 and my bi polar stepper motor?

What is PhaseA? Also can i use a normal diode rather than a zener diode?
It seems to me if the reverse voltage is too large.. just blow up the normal diode will do what for use a zener diode?
 

ivancho

New Member
MC3479 is a bipolar stepper motor driver, and what it does it creates the right sequence for the stepper motor to move. This secuence is the steps need by the motor. Since you have a bipolar motor you have 4 cables, and the IC energize them in the right sequence for movement.

Depending on the resolution of the movement you want out of the stepper you can choose between Full Step, half step and micro stepping. To do full step coil 1 is energized, then coil 2, then again coil 1, etc. The begining of the sequence is what they call PHASE A and you can see it from the attached picture. So you can know when the begining of the rotation starts all over again.

According to the datasheet you can use a normal diode, but they probably must be fast recovery. See datasheet:
VD is normally connected to VM (Pin 16)
through a diode (zener or regular), a resistor, or directly. The
peaks instantaneous voltage at the outputs must not exceed
VM by more than 6.0 V. The voltage drop across the internal
clamping diodes must be included in this portion of the design
(see Figure 6
As to attach it to your PIC you are going to need one for the Clock. The other one to chosse direction CW/CCW. One pin to choose Half/Full stepping and depending on that you need one to control OIC. And then depending on how complex you want to get you can use the PHASEA to determine the start f the sequence and the BIAS/SET to figure out the current used.

I hope it helps!

Ivancho
 

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zhizhi

New Member
By faith i connected everything up and it seemed to work...

When i connect my 12V supply to the motor it jerked abit, d/c and put it back it jerked again...

How can i check if i actually did my PWM worked correctly on the PIC? i do not have an oscilloscope nor a logic probe with me. Does MPLAB's simulator allow me to simulate the PWM?

Or is it some other problems?

Geeh.. this is my first time posting up this forumn and had a quick reply.. this is the best forum i've used...
so far
 

ivancho

New Member
You are driving a stepper motor, that means you need to generate a sequence of signals into its windings to create steps. Lets say that 1 hole revolution has 360 steps, you will have to generate 360 signals so that the stepper rotates 1 turn. When you try to apply this signals to fast the motor will miss some steps, and if it is too fast it will only jerk a little bit.

Try slowing down the signal generation. Normally stepper motors need a ramp to accelerate, by that I mean that the aceleration of the motor shouldn't be from 0 to full speed, but accelerate progressively until reaching full speed or the speed needed.

How is your program and what connections did you make?

Ivancho
 
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