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Stepper Motor Controller Design input — Parallax Forums

Stepper Motor Controller Design input

PhilldapillPhilldapill Posts: 1,283
edited 2009-04-12 07:41 in General Discussion
I'm designing a stepper motor controller for use with bipolar, 2A per phase, stepper motors. I am using the L298N and L297 combo for control and drive. I am trying to make the board as compact as I can, as simple to use as I can, but at the same time, give access to as many input pins as I can.

L297·Datasheet
L298N Datasheet

At first, my approach was to make it as simple as possible - 1 input pin for the direction, and 1 input pin for the "step" or clock. When the clock pin is toggled high-low, the stepper will either step once in the CW or CCW direction, depending on the state of the direction pin. There is another pin on the L297 which allows for either Full or Half stepping, depending on state.

I am having a hard time deciding if I should just give access to ALL the input pins, 6 in total, PLUS the "home" output pin and sync, or should I just stick with breaking out the direction and clock pin, and only allowing access to the Half/Full step pin via a pin jumper. How often are you REALLY going to switch to full step or half step in software? Also, do you see any purpose to having access to the Home, Reset, Control, Enable and Sync pins?

I am designing this for a project of mine, and also to sell, so I'd like it to be user friendly by not overwhelming the user with sooo many pins, but at the same time, have it as versitle as I can for any application. Thanks guys.

Comments

  • $WMc%$WMc% Posts: 1,884
    edited 2009-04-10 03:36
    Philldapill

    Whats wrong with the L293D that Parallax uses?, I'm not trying to be smart here, I'm just asking a question?

    What advantage does the L297 and L298N offer over the L293D?


    ___________________$WMc%________

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    The Truth is out there············································ BoogerWoods, FL. USA
  • willy1067willy1067 Posts: 107
    edited 2009-04-10 04:31
    I built two circuits for controlling as many steppers motors as you many need. using only 3 pins

    here are the shortcuts

    ·http://forums.parallax.com/showthread.php?p=641605 serial expander

    ·http://forums.parallax.com/showthread.php?p=641371 stepper motor controller

    hope you could use it

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Fernando Gomez


    ·http://pinellas-sign-manufacturer.com

    Never compare yourself with anyone else, there will always be someone bigger·or·smaller·than you.
  • PhilldapillPhilldapill Posts: 1,283
    edited 2009-04-10 06:59
    WMc, the L293 is good for small loads that don't need current limiting. It gives you direct control over each output, too.

    The L297/298 combo, on the other hand, allows for current limiting through "chopping". This is automatically done by comparing the current through each winding to a programmable value. This is done at very high frequency, and automatically by the L297. What this does, is allows a constant current that is tuneable, rather than using big external power resistors to limit the current. Also, the interfacing is a little easier since you only need a direction and clock pulse to make the motor move. With the L293, you have to manually pulse each phase with a programmed pulse configuration... a little more complicated for the user.

    Fernando, that's pretty cool with the expander and stepper controller. Just curious, how are you driving the high-side fets? Are you using N-channel, and P-channel together?
  • T ChapT Chap Posts: 4,249
    edited 2009-04-10 17:14
    Phil, I would even suggest that the combo you are looking at is a bit limiting. Why now just look for a more flexible driver, even one with 1/4 or 1/16 steps, plus programmable decay rates, etc. Then you or the user can decide what the voltage and current limitations are based on the fets? My opinion with building CNC machines is to allow for easy change out of motors later if needed, then you have one driver that will suit any size machine/motor requirement. Driving all n channel fets is my choice.

    CNCzone.com is a great source for stepper driver info if you haven't already been there, there is very little that hasn't been thoroughly gone over as far as driver options, fet choices etc.
  • willy1067willy1067 Posts: 107
    edited 2009-04-12 02:48
    I belive the fets are only N-Channel, check the link and parts, it was very easy to put together.

    I also put together my CNC with a router and a laser head, check the shortcut, and a video or two.

    http://forums.parallax.com/showthread.php?p=656332

    I use a 3 axis board from Ebay and KCam software, works great... but I should have use a 4 axis better.


    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Fernando Gomez


    ·http://pinellas-sign-manufacturer.com

    Never compare yourself with anyone else, there will always be someone bigger·or·smaller·than you.
  • $WMc%$WMc% Posts: 1,884
    edited 2009-04-12 07:41
    Philldapill

    Thanks for the info. on the stepper drivers

    You are the Man

    ____$WMc%___

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    The Truth is out there············································ BoogerWoods, FL. USA
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