MechanicalSystem

Machinery Sensor Driver Control

Control algorithm

ControlSystem

Mechanical System

Engineering realization

• Design of Computer Control System

Hardware: Circuit schematic design + PCB

Software : Algorithm + Programing + Software Simulation

• Question

How to choose a appropriate controller or design a control system

Questions

1. How to choose a controller?

2. Step of designing a control system?

3. How to design a MCU system?

4. How to implement the motion control

of step motor?

Robotic Gecko

AVR microcontroller

Contents

1

2

3

4

Classification and characteristics of

computer control system

AVR fundamental setup

MCU development process

Example : stepper motor motion

control

Classification and characteristics of computer control system

ComputerMCU

ARM、DSP embedded

system

PLC

IPC

Universal PC

Dedicated

embedded

systems

MCU

• AdvantagesTargeted

Small size

Low cost

• DisadvantagesLow reliability

Long development cycle

Principles of choosing a MCU

• Micro control system: Using a self-designed

microcontroller, such as Intelligent instrumentation.

• Normal control system: Choose existing industrial

controller in order to speed up development, such as

PLC.

• Large control system: Choose Industrial PC, and use

high-level language to develop or configure software.

Contents

1

2

3

4

Computer control system

AVR basis

MCU system development

process

Examples: stepper motor control

AVR Microcontroller Basics

2.1 MCU basis;

2.2 Development of MCU;

2.3 Characteristics of AVR;

2.4 ATmega 8 architecture and on-

chip resources;

Typical MCU application system

The development trend of MCU: low power consumption,Wide voltage, high-performance, low cost, ISP or ISP baseddevelop environment.

2.1 MCU basis

Definition of MCU:

CPU, RAM, ROM, timer/counter, and I/O interface

circuit and other major computer components are

integrated on a chip, which is composed of such a chip

microcomputer is called the single chip microcomputer.

• MCU performance indicators:

Clock Speed: The CPU clock frequency CPU

Instruction set : CISC and RISC, the later is more efficiency

Word length: The bits of binary number it processed(8 bits is the mainstream)

MCU comparison of similar prices

CPU AT、STC series 51 MSP430F1 AVR

Clock Speed 2MHz 8MHz 20M Hz

Instruction set CISC RISC RISC

Word length 8 bits 16位 8位

2.1 MCU basis

2.2 Characteristics of AVR

AVR program can be written in parallel, or through ISP,

which can be erased online.

Just a parallel port download cable ISP, the debugged

program can be written into the AVR. So, an ISP

download cable can go through AVR development, the

cost is very low.

ATmega8 architecture

2.3 ATmega8 architecture and on-chip resources

Plastic Dual In-Line Package Thin Quad Flat Pack

2.4 ATmega8 architecture and resources

Contents

1

2

3

4

Classification and characteristics of

computer control system

AVR basis

MCU system development

process

Example: stepper motor control

MCU system development process

MCU application system development is the process of achieving a specific function SCM system, according to the needs of customers or markets,

Need analysis

overall design of system

design of the hardware

in the system

system software design

MCU

system simulation

Program download

1

1

3.1 Need analysis

• Goal: Determine the task the system to complete and its function.

• Product design-work instructions

-- SCM system functions implemented

-- Specifications

• Input and output;

• Function and property;

• Cost;

• Physical size and weight;

• Power consumption.

3.2 Overall design of system

• Design description

• General block diagram

• The overall structural design

• Preparatory for design– Plan design schedule and

organize manpower;

– Prepare place and instrument;

– Develop components’ procurement and external processing program ;

– Budget.

3.3 Design of the hardware in the system

• Selection of the components–MCU Selection;

–Select the peripheral device;

• Circuit Design–Standardization and modular of hardware system;

–Plan and control the system resource;

• Computer-aided design of hardware circuits–Schematic Design;

–PCB diagram design.

• Control system = Scheme selection + modeling and Simulation + Hardware development +

software debug + Joint debugging

3.3 Design of the hardware in the system

Software System Development Tools

Compilation tools: ICC AVR

Simulation tools: AVR STUDIO

Download tools: PROGISP

Software Development

• To develop a MCU software system, it generally go through the following process:

Write code compile Simulation Download

• AVR can use assembly language or C language to programme.

• Atmel offer us a suit of develop tools:– Compiling: ICCAVR

– Simulation: AVR Studio

– Download: PROGISP

Connection

ISP

USB

+12V

220V

USB

Serial

communication

Robotic fish motor control

Contents

1

2

3

4

Classification and characteristics of

computer control system

AVR basis

MCU system development

process

Example: stepper motor control

Experimental Platform

USB转串口线

USB to serial

port cable

MCU ISP download

cable

12V

power

Box

Experimental Platform

AVR Development Board

ZLG728

9

Serial

Communication

12V

Power

input

Power

switch

Nixie tube ISP

Control

button

Potentiom

eter

Step

motor

DC motor

interface

Servo

interface

Step

motor

interface

L298

LM780

5

ATmeg

a8

Motor

Control

Jumper

Reset

LED

PCB diagram

SCH layout

Connection

Power port

Serial port ISP port

• Minimum system：Include ISP, maintain the operation of MCU;

• PMU: For power management, The input voltage is 7.5V~24V（12V）；

• RS232communication module: Can undertake serial communication with PC ；

• Keyboard, the analog signal input module: The input control and A/D acquisition experiments;

• LED, Digitron: Common display device；

• Stepper motor module: Control four phase stepper motor

Development board function module

• Input：The AD module; The keyboard module；

• Output：Stepper motor module; LED ;digitron; Steering gear module；

• Input output unit：USART；

Input-output channel

control

systeminput output

I/O

The minimum system wiring diagram

LED1——PC0 LED3——PC2

LED2——PC1 LED4——PC3

LED display

Digitron display

ZLG7289 Digitron

CS_7289

CK_7289

D_7289

CS_7289——PD5

CK_7289——PD6

D_7289 ——PD7

LED and digital display wiring diagram

Serial port communication

This part by PC

This part to the TXD、

RXD of MCU

Max232PC MCU

TXD

RXD

Serial port communication wiring diagram

Keyboard interface module

SW1——PD2(INT0)

SW2——PD3(INT1)

normal state Key

down

Key

up

AD collection module

AD7——ADC7

potentiometer AVRAD7

analog

voltage

0～VCC

digital

quantity

0～1023

Input module wiring diagram

Stepper motor control instance

• Use AVR chip as main control unit ，L298

As the driver chip . Control block diagram

is as follows ：

AVR L298Step

Motor

• Displacement: proportional to the input pulse

number strictly

• Rotating speed: proportional to the pulse frequency

•Direction: related to the winding way of electricity

Stepper motor

No. A B C D Dir

1 1 0 0 0 Reverse

Forward

2 1 1 0 0

3 0 1 0 0

4 0 1 1 0

5 0 0 1 0

6 0 0 1 1

7 0 0 0 1

8 1 0 0 1

Four phase eight beats circular distributor

numerical tables as follows

Circular distributor

Stepper motor module

L298 stepper motorIN2

IN3

IN3

IN1

IN1——PB1

IN2——PB3

IN3——PB2

IN4——PB4

Stepper motor layout

• ICCAVR main interface

source file editor window

The Project Manager Window

Compile status window

• Build a new project

• The wizard is used to establish the file, added to the project project

file

wizard

Choose the chip and XTL ：

– as follows ，the chip is Atmega64，XTL is 11.059MHz ，External interrupt 4 (rising along the trigger)

• I/Osetting

select the corresponding state according to the need。in the graphic ：PB0 output high level;PB1 output low level；PB3 is high resistance 。

Progispfunction：download the program from PC to MCU

• Choose chip ATmega 8

• Set the programming options （Choose the chip erase,

programming FLASH, calibration FLASH ）->Load Flash->click automation

①

②

③

④

Let us see how the

Step motor works…

The stepper motor

24BYJ48A

• Stepper motor speed control

Control stepping motor speed is to control pulse frequency or

phase of the cycle。

Two way：

software delay：By calling the delay subroutine method, it

takes up CPU time.

Timer ：By setting the TOCNT register.

Stepper motor drive circuit

PB1(OC1A)、PB3(MOSI)、PB2(OC1B)、PB4(MISO)

respectively control A、B、C、D phase。

Jumpers：3---2、6---5、9---8、12---11。

Three sets of control scheme

• Pure MCUprogram control

• Potentiometer and the button control

• upper computer control

Pure MCU control

• Stepper motor speed and direction decide

by the burning process, if you want to

change the speed and direction of step

motor, you can only change in the original

MCU program, burning again.

• Usually the final actual running program is

implemented in this way.

AD sampling circuit and buttons

MCU AD samples analog voltage value to control the

speed of the stepper motor。Two buttons control the direction of stepping motor。

Four phase stepper motor control algorithm

• 1、 Four phase four beat：A->B->C->D->A

• 2、 Four phase double four beat：

AB->BC->CD->DA->AB

• 3、 four phase eight beat:

A-> AB-> B->BC-> C-> CD -> D-> DA->A

Two key points of stepper motor control

• Angular displacement: pulse number

• Speed: pulse frequency

360=

ZNstep angle

60 fSpeedn

ZN （r/min）

Z is the number of teeth on the rotor type, N is the number of beats, f is pulse frequency

What we do now

• 1、 What kind of pulse we need？

• 2、How to generate the pulse ？

– How to produce a certain number of pulse ？

– How to produce the required frequency pulse ？

How to generate pulse signal

• Timer of the MCU --- generate pulse

– Regularly produce beats

– Use PWM function

• Timer generates a certain number of pulse.

change winding current order in Overflow timer interrupt.

• Change the timing - to produce the required frequency pulse

AD sampling circuit and buttons

MCU AD samples analog voltage value to control the

speed of the stepper motor。Two buttons control the direction of stepping motor。

Review our learning ：

development board frame

ICC

AVR Studio

AVR AVR JDK sample

functional modules

download softwareProgi

sp

Stepping Motor control exp

eriment

powerMinimum

system

Serial Communi-

cationMotor Module

Digitaldisplay

buttons

LEDAD

sampling

Learning resource

• 1. guidance notes;

• 2. OurAVR Website: www.ouravr.com;

• 3. ATmega8 Datasheet;

• 4. C programming;

MIT Cheetah Robot