Struggling to drive a stepper motor

Thread Starter

stylediva

Joined Dec 6, 2011
72
i want to drive the stepper motor for my robotic arm project..plz guide me with the controlling circuitry..i have attached the schematic..will it work??..also tell me what type of motor is suitable..unipolar or bipolar??..i m new to this..help..
 

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SgtWookie

Joined Jul 17, 2007
22,220
The schematic is more or less the same as what is in the L297 datasheet; schematic at the bottom of the 1st page:
http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/DATASHEET/CD00000063.pdf

The L298 is very old, and is probably only still around because people need to replace them all the time. At full load, there is about a 4 volt drop across the bridge due to the use of Darlington transistors, and the bridge will dissipate about 20 Watts of power, which is why they are so easy to burn up.

THe L298 was made with bipolar steppers in mind. It would not work to drive a stepper motor as unipolar.

We know nothing about your "robotic arm". We don't know if it is made out of toothpics, trusses from a bridge, or anywhere in between.

Are we supposed to guess all this stuff?
 

Thread Starter

stylediva

Joined Dec 6, 2011
72
we will made that with stainless steel or aluminium..now i just need controlling circuitry of driving stepper motor..help..
 

SgtWookie

Joined Jul 17, 2007
22,220
we will made that with stainless steel or aluminium..now i just need controlling circuitry of driving stepper motor..help..
You have to know what your load will be before you can select a motor.
You have to know your motor requirements before you can select a motor driver.
 

SPQR

Joined Nov 4, 2011
379
I'm going to jump in here and give a "Newbie" perspective, because I've gone through stepper motor learning over the last six months (It's been a blast!). At the beginning I started "thinking from the electronics I wanted to make and applying it to the mechanics", then after learning quite a bit, I've turned it around to "thinking of the mechanics first, then driving those mechanical gadgets with electronics that is appropriate for them".

1. I say "Amen" to SgtWookie! One of the things I learned is that you have to do your "mechanics" first. Think about the mechanics of the project, or even build the mechanical part first. Then you can choose your stepper.

2. You'll choose the "size" of the stepper - so you'll learn about NEMA (RepRapWiki).

3. Then you'll choose the torque in Oz-inches or Newton-cm -
This motor from SparkFun, you can stop with your fingers.
This Vexta motor can't be stopped with pliers!!
Tons of steppers to choose from.

4. Once you've chosen your motor, you'll know how much current you need then you can choose a driver.
The Easydriver will give you up to 0.75 amps per phase.
The Big Easydriver will give you 2 amps per phase.
The Interinar driver will give you 2.5 amps per phase.
There are tons of drivers available out there.

5. Then you choose a power supply.


I'd be interested in hearing comments from the experts regarding my thoughts above.
 

Thread Starter

stylediva

Joined Dec 6, 2011
72
i m not getting the idea of how to interface the L297 with avr atmega16..plz help me in the code..tell me how to interface that..help..
 

SgtWookie

Joined Jul 17, 2007
22,220
The driver you attached in your 1st post would work with a bipolar stepper motor, if you had sufficient voltage to drive it with.
 

Thread Starter

stylediva

Joined Dec 6, 2011
72
tell me the sufficient voltage..also plz tell me what should i need to do with the enable, clock and CW/CCW pins..should i need to give them to controller..??..or else??..what should be the frequency of operation??..guide me with this..
 

SgtWookie

Joined Jul 17, 2007
22,220
I have no idea what you will need, as you haven't shown the specifications for your motor.

If you still don't know what motor to get, then you will have to define what your power requirements are.

It seems like you want us to do all of the thinking for you, when we really know very little about your project, except that it is supposed to be some kind of mechanical arm. You have not even given us a hint at how large it might be.
 

Thread Starter

stylediva

Joined Dec 6, 2011
72
i have checked the driver on proteus..its working..but only in one direction..what should i need to do with the clock..kindly tell me the errors..help..
 

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Thread Starter

stylediva

Joined Dec 6, 2011
72
sir actually i want to drive the bipolar stepper motor..i m working on this driver..i just need to drive the bipolar motor driver in order to learn about the stepper motor working....
 

Thread Starter

stylediva

Joined Dec 6, 2011
72
actually i want to control the positions and angles of my stepper motor..the motor which i m using is 6-wired 1.8 deg 2A.plz guide me what shud i do..will it work with only L298 driver ic??...if so then what will be the coding if i interface that with avr??..or shud i use L297/L298 driver..plzz guide me..i m not getting anythng..:(
 

SgtWookie

Joined Jul 17, 2007
22,220
actually i want to control the positions and angles of my stepper motor.
That's usually what people want to do with them....
The motor which I am using is 6-wired 1.8 deg 2A.
Well, that is a unipolar motor. The L298 is for bipolar motors.
4-wire motors are bipolar. 6-wire motors are unipolar. 8-wire motors can be run as either bipolar or unipolar.
It is possible to use a 6-wire unipolar motor as a bipolar motor, but that doubles the voltage required - you are better off to use it as a unipolar motor.
You did not tell us what the voltage of the motor is.

plz guide me what shud i do..will it work with only L298 driver ic??...if so then what will be the coding if i interface that with avr??..or shud i use L297/L298 driver..plzz guide me..i m not getting anythng..:(
Here is a great resource for you:
http://www.divms.uiowa.edu/~jones/step/
Please read through all of that information, at least twice.

As far as helping you more; I most likely will not be able to do that for a period of time. I am having heart surgery in the morning, and will be recovering from that for several weeks. I don't know if I will have access to the Internet, AND feel like helping people too.

Perhaps someone else will help you.
 

thatoneguy

Joined Feb 19, 2009
6,359
You have a problem with the motor power supply on the driver IC.

Why is OUT2 connected to Vs?

Why is Vs connected to the diodes (correct), but not the IC?

Please clean up schematic, spread parts out a bit more and get rid of unneeded kinks and twists in the lines. Increase the font size a touch, so the IC numbers are easily read.

Where is the AVR in the schematic? Place it with power and bypass caps, and I can let you know what needs to be driven once your driver circuit is cleaned up.
 
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