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Application Report
SNOA184D–October 1993–Revised May 2013
AN-706 LM628/629
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ABSTRACT
This application report is intended to explain and complement the information in the data sheet and also
address the common user questions. While no initial familiarity with the LM628/629 is assumed, it will be
useful to have the LM628/629 data sheet close by to consult for detailed descriptions of the user
command set, timing diagrams, bit assignments, pin assignments, and so on.
Contents
1 Introduction .................................................................................................................. 3
1.1 Objective ............................................................................................................ 3
1.2 Brief Description of LM628/629 .................................................................................. 3
2 Device Description .......................................................................................................... 4
2.1 Hardware Architecture ............................................................................................. 4
2.2 Motor Position Decoder ........................................................................................... 5
2.3 Trajectory Profile Generator ...................................................................................... 7
2.4 Definitions Relating to Profile Generation ...................................................................... 7
3 Profile Generation ........................................................................................................... 8
3.1 Trajectory Resolution .............................................................................................. 8
3.2 Position, Velocity and Acceleration Resolution ................................................................ 8
3.3 Velocity Mode ...................................................................................................... 9
3.4 Motor Output Port .................................................................................................. 9
3.5 Host Interface ..................................................................................................... 10
3.6 Hardware Busy Bit Operation ................................................................................... 10
3.7 Filter Initial Values and Tuning ................................................................................. 12
4 User Command Set ....................................................................................................... 13
4.1 Overview ........................................................................................................... 13
4.2 Host-LM628/629 Communication—the Busy Bit ............................................................. 13
4.3 Loading the Trapezoidal Velocity Profile Generator ......................................................... 13
4.4 Loading PID Filter Coefficients ................................................................................. 15
4.5 Interrupt Control Commands .................................................................................... 15
4.6 Data Reporting Commands ..................................................................................... 16
4.7 Software Example ................................................................................................ 16
5 Helpful User Ideas ......................................................................................................... 19
5.1 Getting Started .................................................................................................... 19
5.2 Hardware .......................................................................................................... 19
5.3 Software ........................................................................................................... 20
5.4 Initialization ........................................................................................................ 21
5.5 Performance Refinements ....................................................................................... 21
5.6 Operating Constraints ............................................................................................ 22
6 Theory ....................................................................................................................... 23
6.1 PID Filter ........................................................................................................... 23
6.2 PID FIlter Coefficient Scaling Factors for LM628/629 ....................................................... 23
6.3 An Example of a Trajectory Calculation ....................................................................... 26
7 Questions and Answers .................................................................................................. 28
7.1 The Two Most Popular Questions .............................................................................. 28
7.2 More on Acceleration Change .................................................................................. 28
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1
SNOA184D–October 1993–Revised May 2013 AN-706 LM628/629
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Copyright © 1993–2013, Texas Instruments Incorporated
Verzeichnis
- ・ Blockdiagramm on Seite 3
- ・ Anwendungsbereich on Seite 31
