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Easy Step n - Introduct to Stepper Motor
EASY STEP'n,
An Introduction to Stepper Motors for the Experimenter from Square 1 Electronics,
written by David Benson
Table of Contents
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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 (R) instruction set
Hexadecimal notation
Compare using PICMicro(R)
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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