Discussion in 'The Projects Forum' started by thinkbig, Nov 30, 2008.

  1. thinkbig

    Thread Starter New Member

    Nov 25, 2008
    hey keerthi,
    even i m building a micromouse can you help me with which sensor and how to use them.........
    i would like to know which are the stepper motor drivers available for a typical 9V bipolar stepper motor...
    i am confused between ULN2003 and L298...
    pls help..........
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    We really prefer you to start a new thread for each topic, even if it's related. This is the old thread - http://forum.allaboutcircuits.com/showthread.php?t=15383.

    You can get the difference with the data sheets. The ULN2003 is an array od Darlington transistors, while the L298 is a specialized IC stepper driver.
  3. SgtWookie


    Jul 17, 2007
    Unipolar stepper motors are easier to work with than bipolar stepper motors.

    Unipolar stepper motors generally have five or six leads. The coils in a unipolar stepper motor are center tapped, where the power is connected. The motor can be stepped by grounding the ends of the coils in sequence. A ULN2803 or ULN2066 Darlington driver IC can be used in conjunction with other logic or microcontroller to switch the coils in sequence.

    Bipolar stepper motors require that the current direction through the coils can be reversed. This requires an "H-bridge" driver circuit for each coil. The L298 is a dual H-bridge designed for controlling low-power bipolar stepper motors.
    Bipolar stepper motors generally have four leads, but they may have eight.
  4. hgmjr


    Jan 28, 2005
    I concur with sgtwookie's comment that unipolar stepper-motors are a good place to begin your exploration of the technology and the controls.

  5. SgtWookie


    Jul 17, 2007
  6. Alberto

    Active Member

    Nov 7, 2008
    Last edited: Nov 30, 2008
  7. thinkbig

    Thread Starter New Member

    Nov 25, 2008
    thank you guys for helping....
    I am using a unipolar stepper motor.

    Can anyone help me out with how to connect a L298 IC to AVR microcontroller(as in circuit diagram).
    I am using ATmega16 or Atmega8.
  8. SgtWookie


    Jul 17, 2007
    What are the specifications for your unipolar stepper motor?
    Do you have a datasheet for it? Or manufacturer and part number?

    An L298 could be used, but it will double your voltage requirements.

    A ULN2803 (Eight Darlington pairs) would drive a single stepper motor at up to 500mA current, or two at up to 250mA each.
    A ULN2066 (Four Darlington pairs) would drive a single stepper motor at up to 1.5A.
  9. thinkbig

    Thread Starter New Member

    Nov 25, 2008
    hey dude thanx for d reply..

    m using UNIPOLAR STEPPER MOTORS (6-12V,500mA)..
    i need to drive two such steppers..
    i wanna drive both d steppers at 500mA onli..

    so i think 2 2803s will b needed..

    may u plz provide with d suitable ckt n some more help in that context!!
  10. SgtWookie


    Jul 17, 2007
    Correct spelling, punctuation and grammar are appreciated on these forums. Please avoid using "shorthand", as people will not take you seriously.

    You might be better off using two ULN2067B IC's, one for each stepper motor.
    Newark carries them for $2.11 each.
    You could use ULN2803B's if you wanted to.
    Newark carries them for $0.414 each:
    However, you're usually better off to use components rated for more than your actual load.

    I am not familiar with Atmel's ATmega16 or Atmega8, so I'm not going to be much help there. However, a quick glance at the ATmega16 datasheet suggests that perhaps port C would be suitable. This would leave port A completely free for ADC functions that will be necessary for various sensors, and it looks like port B may have some functions that you wouldn't want tied up with your stepper driver output-only scenario.

    If you don't have a schematic capture/board layout program, you might consider downloading Cadsoft's Eagle Layout Editor. The free version can generate boards up to 3"x4" with two layers of traces.

    Someone who knows AVRs would be a much better advisor for you on your interconnections.

    It might be time for this thread to be moved over to the microcontroller forum.