08-Chapter 8 - Microcontrollers

8/12/2019 08-Chapter 8 - Microcontrollers

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Chapter 8

Microcomputers



Microcomputer Microcontroller

What’s the difference?



Homework 7

1. What is a microcontroller?

What are some common applications of these?

A microcontroller is a simple computer on a single

silicon chip that cost only a few dollars.

They are useful in washing machines, toasters, andcars.



Microcontrollers in Cars and Trucks?

All modern automobiles contain at least one

microcontroller, and can have as many as six or

seven.

The engine is controlled by a microcontroller, as are the

anti-lock brakes, the cruise control and so on.



Interesting…

Any device that has a remote control almost certainly contains a

microcontroller: TVs, VCRs and high-end stereo systems all fall

into this category.

Digital cameras, cell phones, camcorders, answering machines,

laser printers, telephones (the ones with caller ID, 20-number

memory, etc.), pagers, and feature-laden refrigerators,

dishwashers, washers and dryers.

Basically, any product or device that interacts with its user has a

microcontroller buried inside.



PIC Microcontroller

• We will use the 16F84A microcontroller made by

Microchip for the team project. Use the Internet to

research these chips.

http://www.sparkfun.com/shop/index.php?shop=1&cat=69

http://www.sparkfun.com/shop/index.php?shop=1&cat=69



Acronyms

IC

RAM

ROM PROM

EPROM

EEPROM

PIC



IC – Integrated Circuits

http://upload.wikimedia.org/wikipedia/commons/c/ca/Memory_module_DDRAM_20-03-2006.jpg



RAM – Random Access Memory







ROM – Read Only MemoryROM cannot be modified (at least not very quickly or easily),



ROM – Read Only MemoryROM cannot be modified (at least not very quickly or easily),



PROM – Programmable Read Only Memorysetting of each bit is locked by a fuse



Google “PROM Memory”



EPROM – Erasable Programmable Read Only Memory

http://upload.wikimedia.org/wikipedia/commons/5/5c/Microchips.jpg




http://upload.wikimedia.org/wikipedia/commons/b/bc/DSCN0411.JPG


http://slidepdf.com/reader/full/08-chapter-8-microcontrollers 15/52EEPROM – Electronically Erasable Programmable Read Only Memory





http://upload.wikimedia.org/wikipedia/en/5/5c/USB_Flash_Drive.png



EEPROM El t i ll E bl P bl R d O l M



EEPROM – Electronically Erasable Programmable Read Only Memory



PIC – Programmable Integrated Circuits



The SFA Rover

Team Project



The Vehicle Course

50-feet

6-feet



The Vehicle Course

50-feet

6-feet

Extra Credit



Scoring

D = Distance traveled in feet in 10 minutes

(the maximum distance is 50-feet)

R = 15 if the vehicle successfully demonstrates avoiding an obstacle on

the right and 0 if it is not demonstrated

L = 15 if the vehicle successfully demonstrates avoiding an obstacle on

the left and 0 if it is not demonstrated

T = -10 each time the vehicle is touched by a team member during the

course

Grade = T + L + R + D × 70/(50ft)

Bonus: For each extra left or right obstacle avoided, 2 points of extracredit will be earned for each member of the team. A maximum of 20extra points can be earned in this manner.



Left

Button

Right

Button

PIC

Microcontroller

H-Bridge

9-Volt

Battery

Right

Motor

Left

Motor

Voltage

Regulator

SFA Rover Circuit Diagram



Key Concepts

Note that the parts used in the team

project are discussed in your text book.

Chapter 7 - Logic Circuits Chapter 8 - Microcomputers

Chapter 10 - Diodes (Voltage Regulator)

Chapter 12 - Transistors (H-Bridge)

Chapter 16 - DC Machines (Motors)



Key Concepts

Other key ideas used in this team projectinclude:

Battery Power Management

Torque

Friction

Gearboxes

We will now design circuits that will be used inlab next week.



Chapter 10

Diodes



Semiconductors

Germanium

32 protons

Silicon 14 protons

Most commonly used



How many electrons can be in the ground state of

an atom?

Answer: 2 (s level)

...in the first excited state?

Answer: 8 (s and p levels)

…in the second excited state?

Answer: 8 (s and p levels)

Atomic Physics



Valence Electrons

Valence electrons are electrons in theoutermost shell of the atom that can

participate in forming chemical bonds with

other atoms.

How many valence electrons does Silicon

have? Answer: 4



How many electrons are needed to fill the

outermost energy level of Silicon?

Answer: 4

2-D representation of Silicon Crystal

How many valence electrons does Phosphorus

(15P) and Aluminum (13Al) have?

Answers: 5 and 3



Diodes

Conduct electricity in one direction

Two terminal devices anode and cathode

Primarily made of silicon





DopingThe adding of impurities

n-type crystal

e.g. Silicon doped with Phosphorous

negative charge carriers

electrons

p-type crystal

e.g. Silicon doped with Aluminum

positive charge carriers

vacancy or hole



Diodes

p-type n-type

Circuit Symbol



Flapper Valve Analogy

Flapper

Valve Analogy



Diode Characteristics

Forward-Bias Condition

Good Conductor

Reverse-Bias Condition High Resistance

I versus V Plot

Ideal Diode and Real Diode “Knee” and Breakdown Voltage

Three Regions



Shockley Equation

Shockley Equation on Excel

Common LED have a maximum recommendedcurrent of 20mA.

What resistor value is needed in series with an LEDand a 5-Volt power supply so that the LED does not

burn up?

Answer: _______ or ________

1nkTqvexpIi D

sD



What does the circuit symbol for an

LED look like?



Diode Circuits

rec·ti·fi·er Pronunciation: 'rek-t&-"fI(-&)rFunction: noun Date: 1611

: one that rectifies; specifically : a device forconverting alternating current into direct current

Half-Wave Rectifier

Full-Wave Rectifier

Bridge Rectifier

http://www.m-w.com/cgi-bin/dictionary?book=Dictionary&va=rectifies

http://www.m-w.com/cgi-bin/dictionary?book=Dictionary&va=rectifies









Smoothing Capacitors

Ripple Voltage (Vr )

DC Component (VDC)

Ripple Factor

DCVVr



Concept Test

Is a high or low value for the ripple voltage V

desirable?

Answer: Low

What are three ways to achieve low ripple

voltages?

Answers:

Low CurrentHigh Frequency

High Capacitance



Zener Diodes

Zener Diodes are intended to operate in thebreakdown region.

Manufacturers set the breakdown voltage by

modifying the doping.

Zener diodes can make good voltage regulators.

Circuit Symbol

Clarence Zener once visited SFA.

Wh t i Z di d ? H d th



What is a Zener diode? How do the

circuit symbols for a diode and a Zener

diode differ? Zener diodes are intended to operate in the

breakdown region -usually as voltage

regulators.Manufacturers set the breakdown voltage by

careful doping.



How do you convert AC to DC?

Voltage Regulators remove the ripple.

Diode

RectifierSmoothing

Capacitor

Voltage

Regulator

AC Input

DC Output



Concept Question

What components to you need to convert a 110-Volt ACsignal to a 9-Volt DC signal?

Answers:

Transformer – to step down the voltage

Diodes – to rectify the waveform (make +) Capacitor – to smooth the rectified waveform

Voltage Regulator – to remove the ripple

Note that the device connected to this 9-Volt power supplyacts as a resistor.

For this reason the device is sometimes called the “load” or“load resistance”.



Example Questions

10.32, 35

Homework Questions?

10.55, 56, 57, 35



What is an ideal diode?

An ideal diode is a perfect conductor

with zero voltage drop in the forward

bias direction…

…and a perfect insulator in the reverse

bias direction.



Stop Here



What element from the periodic

table are diodes made of?

Silicon

08-Chapter 8 - Microcontrollers

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