Gernal Aspects of Electronics

8/8/2019 Gernal Aspects of Electronics

1/25

5thh ational robot contestational robot contestresentation on generalresentation on generalspects of electronicsspects of electronics

Presented by

Deepak ParajuliGiresh kunwar


2/25

What is ROBOT

widely used in manufacturing, assembly andpacking, transport, earth and space exploration,

surgery, weaponry, laboratory research, andmass production of consumer and industrialgoods.

v ,an automatically controlled, ,reprogrammable multipurpose manipulator

,programmable in three or more axesfixed or mobile


3/25

ROBOT DissectionMechanical body

Electronic automation

Automatic movement ormanual control


4/25

Major ElectronicsHardwarevSensorsvMain controller (robot brain)

vMotor drivers and actuators

SoftwarevLanguage and Tools(assembly ,c , keil, mplab)vSimulators(proteus, EWB)


5/25

General Block Diagram of

Robotic System

Microcontroller

sensor

sensor

sensor

Se

nsor

condition

ing

Out

put

interfaces

actuator

indicator


6/25

sensorsTouch sensorPhoto diode

Photo transistorLDR

IR

Ultra Sound

Image sensorGyro sensor


7/25

Sensors(cont...)


8/25

Use of sensorsWhite strip(line) detectionProximity detection

Obstacle detectionObstacle avoidance

Inter robot communication


9/25

Main controller(robot

brain)Different families of microcontroller ATMEL, Motorola, Texas Instuments, Zilog

Microchip PIC

AVR etc.Selection Criteria of microcontrollerComputing needs of the task efficiently(speed, memory, I/O ports, Power

consumption, cost/unit)

Availability of software development tools(compiler,

simulator, assembler, debugger, technical support)Market availability

Availability of reliable source of information


10/25

Motor Driver circuits and

MotorsElectromechanical Relay switchingRelay driver(ULN 2 0 0 3 )

MOSFET H- bridgeMotors

Wiper motor (high torque low speed)

Dc motor (moderate torque/ moderate speed)

Stepper motor (precise control/low torque)

OptocouplersBlocking the noise from motor controller and motors to pass

to the main controller circuit.


11/25

Motors (cont...)

W ip e r

m otor

Step pe rm otor

G e a r h e a d e d D Cm otor


12/25

H- bridge


13/25

Relay switching

D P D P re la y w ith

ice cubep acka g in g

D iffe re n t rela ysw itch in g

S o lid sta te re la y


14/25

PCB designing Mechanical etching(etching machine takes more than 1 hr) Chemical etching(Conc HCl and H2O2 takes 30 minutes)

Single layer PCB

Double Layer PCB

Multi layer PCB

Circuit design considerations Avoid large looping of wires (cause noise coupling)

Avoid large component leg length(acts as antenna in high

frequency) Greater conductor spacing (to reduce noise coupling)

Avoid ground looping(to eliminate unwanted current to flow)

Place decoupling capacitor across each IC (to eliminate noise topass to the IC)


15/25

Software aspects of

microcontrollerIt deals with inputs that comes from real world

and give output to the real world.

Popular microcontrollers: 8051 family : AT89s51, AT89s52, AT89C51,

AT89C52 PIC family : PIC16F877A AVR controllersPIC and AVR controllers available in markets have

extra features like PWM,ADC than 8051.


16/25

On-Chip Facilities OverviewAT89S51

Parallel Input/Output PortsSystem Clock Generator

Timer/CountersInterruptsSerial Port

PIC 16F877A

PWMADC


17/25

Parallel Input/Output

PortsFour 8-bit I/O ports.Each bit is individually usable for up to 32 1-bit

ports.

All ports are bidirectional and direction can beset in SFRs in software.

Some of the pins have alternate functions.


18/25

System Clock Generator

8051 uses 12 system clock cycles per machinecycle.

PIC 16F877A uses 4 system clock cycles permachine cycle.

In p u t

circu it S yste m C lo ck


19/25

Timer / Counters8051 has two 16-bit programmable timers.Timers increment on each system clock.

vEach timer is associated with correspondingSFRs (TLx, THx, TMOD) and can be read orwritten to.

Uses

Generate delay.Measure time interval between events.

Generate time out signals.


20/25

Interrupts8051 has five sources of interrupts:Two External Hardware Interrupts

Two Timer interrupts

Serial port events (buffer full, buffer empty)

Interrupt enabled or disabled using SFRs(IE,

TCON).


21/25

Serial Port (UART)8051 has one serial port.

Data can be sent and received serially.

Baud rate must agree between sender andreceiver.

Transmission modes are selected usingSFRs(SCON).

S e ria lPort

( )T X tra n sm it

( )R X receive


22/25

Pulse Width

Modulation(PWM)Used for generating variable speed.PWM uses single bit output to generate an

analog value proportional to the desired

speed of the motor.


23/25

Software tools and

languages a n g u a g e s w e h a ve b e e n u sin g to m a ke:ra in o f R o b o t

Assembly language C language


24/25

Software tools and

languagesSoftware tools used to simulate brain ofRobot:

SDCC(small device c compiler, free and open

source) Keil (free version is limited .... Like it can debugonly 2k out of 8k code in at82s52,produce hexfile of max size up to 16k)

MPLAB IDE(free IDE provided by MPLAB for PICcontrollers bundled with assembler s and Ccompilers and debuggers from various vendorsbut these compilers are limited in free version

Proteus VSM

Software tools for AVR are generally free and opensource


25/25

Best of luck for 5th national robot

contest

Thank you

Gernal Aspects of Electronics

Documents