This book was written by David Benson (8-1/2 x 11", 200 pages, $34.95). David is also the author of "Easy PIC'n", "PIC'n Up the Pace," and "PIC'n Techniques", which are books instructing people on how to use Microchip's PICmicro® microcontrollers. If you are interested in this subject, visit our other website at http://www.sq-1.com.

INTRODUCTION

Terminology

Coil vs. winding vs. phase

Stepper Motor Types

Stepper Motor Specifications

Stepper Motor Selection Criteria

Stepper Motor Sizes

NEMA "Teen" Cubes

NEMA Size 23 Cylinders

Stacked Cans With Diamond-Shaped Mounting Flange

Rough Motor Specs - Based On My Experiments

Gear Puller

GETTING STARTED

4-Phase Stepper Motors

Exercise motor with four SPST toggle switches and a power supply

Testing 5-wire and 6-wire motors

- Full steps - one winding energized (wave drive)

- Full steps - two adjacent windings energized in each

  detent position (normal mode)

- Half steps - alternately one winding energized, two

  adjacent windings energized

Testing an 8-wire motor

2-Phase Stepper Motors

Determine wiring with ohmmeter

Exercise motor with two DPDT on-off-on toggle switches and a
    power supply

- Full steps - one winding energized (wave drive)

- Full steps - two windings energized (normal mode)

- Half step sequence - alternately one winding energized,

  two windings energized

MICROCONTROLLER-BASED STEPPER MOTOR CONTROL - INTRODUCTION

PICMicro® instruction set

Hexadecimal notation

Compare using PICMicro®

Interrupt service and saving context

TEST CIRCUITS OVERVIEW

Overview

Test Board for Exercising Stepper Motors

Pulser

Switches And Pull-ups

Construction Techniques And Board Design

Pulser software

Testing the pulser

Translators

PIC16F84A translator (unipolar bit pattern)

- Software design

- Hardware design

- Code

- Testing the PIC16F84A unipolar translator

PIC16F84A translator (bipolar bit pattern)

- Design

- Code

- Testing the PIC16F84A bipolar translator

Simple Drivers

Unipolar

Simple ULN2803A driver

Exercising a unipolar stepper motor using a pulser, PIC16F84A
    translator and a ULN2803A unipolar driver

Simple TIP120 driver

Exercising a unipolar stepper motor using a pulser, PIC16F84A
    translator and a TIP120 unipolar driver

UCN5804B translator/driver

Exercising a unipolar stepper motor using a pulser and a UCN5804B translator/driver

Bipolar

H-Bridge

L293D driver (dual H-bridge)

Exercising a bipolar stepper motor using a pulser, PIC16F84A
    translator and an L293D bipolar driver

L298N driver (dual H-bridge)

Exercising a bipolar stepper motor using a pulser, PIC16F84A,
    translator and an L298N biopolar driver

TORQUE MEASUREMENT

Motor (what's available) via lever arm and weights

- Holding, add weight until slips

- Moving, add weight until won't turn

Application (what's required) via lever arm and weights

Lever arms and fishing sinkers

MAXIMUM STEP RATE MEASUREMENT

MICROCONTROLLER-BASED STEPPER MOTOR CONTROL

Unipolar

Simple unipolar stepper control - straight line code

Full steps - one winding energized

How to reverse direction

Change delay time to change speed

Table lookup and counter to get bit pattern for each step

Full steps - two windings energized

Half step sequence

Exercising a unipolar stepper motor using a microcontroller,
    PIC16F84A translator and a ULN2803A or TIP 120 unipolar driver

Exercising a unipolar stepper motor using a microcontroller and a UCN5804B translator/driver

Bipolar

Exercising a bipolar stepper motor using a microcontroller and
    an L293D or L298N bipolar driver

HIGH PERFORMANCE DRIVE CIRCUITS - Current Control

Limitations of voltage control and need for high performance current control

Unipolar

SLA7024M unipolar driver - Allegro

Exercising a unipolar stepper motor using a pulser, PIC16F84A
    translator and a SLA7024M driver

- Maximum stepping rate at higher than rated voltage

- Torque operating at higher than rated voltage

Bipolar

L297/L298N bipolar translator/driver

Exercising a bipolar stepper motor using a pulser and a L297/L298N translator/driver

- Maximum stepping rate at higher than rated voltage

- Torque operating at higher than rated voltage

Exercising a bipolar stepper motor using a microcontroller and a     L297/L298N translator/driver

Controlling A STEPPER MOTOR WITH A PC

Serial port, parallel port

Programming languages

Port board, not mother board

MECHANICAL CONSIDERATIONS

Mounting The Stepper Motor And Heat Dissipation

Grabbing On To The Shaft = Mechanical Connection

Avoid damaging the shaft (clamp, flat, split hub)

Shaft couplings - alignment, flex

Avoid applying a thrust load to the shaft

Converting Rotary Motion To Linear Motion

Mechanics

Torque

Inertia

Position - Home Or Starting Position Sensor

Test for accuracy

Backlash

NEMA 23 Tester

PRINTER EXPERIMENT

Software design

Code snippet

Implement your design

QUICK STEP'n

Test Hardware

Software design details

Home Position

Ramping up/down and rapid traverse

- Ramping up - acceleration

- Ramping down - deceleration

Speed - rapid traverse

Destination

More software details

Code

APPENDIX A - Fast Diodes

APPENDIX B - Parts Lists

APPENDIX C - Sources

APPENDIX D - Program Listings vs. Page Number

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This page last updated February 22, 2008

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