tema4 sistemas digitales microprocesador

8/13/2019 Tema4 Sistemas Digitales Microprocesador

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Microprocessor-based Digital Systems 1

Seminarios-Taller de Informtica Hardware

Microprocessor-based Digital Systems

Grado en Ingeniera Informtica

Primer Curso


Agenda

1. Microprocessor-based Embedded Systems

2. Microcontrollers

3. Skybot Robot


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Microprocessor-basedEmbedded Systems



Computers

When you hear the word computer, you always think

of a desktop computer:

But we are surrounded by thousands of invisible

computers, embedded in complex devices


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Embedded Computers

Every electronic or electromechanical system has a

computer (or many) embedded in it:


So What Is an Embedded System?

An embedded system is a special-purpose computer

system built into a larger device

Embedded systems are required to meet very different

requirements than a general-purpose personal computer

Two distinguishing characteristics:

Cost: Since embedded systems are produced in the tens of

thousands to millions of units range, reducing cost is a major

concern. Embedded systems often use a (relatively) slow

processor and small memory size to minimize costs

Space and Power consumption: Usually embedded systems

have tight space limitations, so they must be built out of a

few components (this also benefits the cost) and complex

power dissipation mechanisms (like fans) are not allowed


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What Is an Embedded System?

Software Issues

The third feature of a embedded system is that it is

single-functioned, not general-purpose like a desktop The SW run in the embedded systems is called Firmware

It is stored in non-volatile memory (Flash, ROM)

At most they have a simple operating system, but in

most cases the have no OS at all

A embedded system is a real time computer

Continually react to changes in the systems environment

Reliability is a must In most embedded systems a software crash is simply not

allowed, e.g. ABS brake system or DVD player


A Little History

One of the first embedded systems was the Apollo

Guidance Computer, started in 1962:


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The Apollo Guidance Computer

Developed by the Charles S.

Draper team at the MIT

The first computer built using

ICs (4100 3-input NORs

connected by wire-wrapping)

4K RAM (ferrite core)

32K ROM (core rope mem)

11 instructions

16 registers

5 vectored interrupts

Programmed in assembler, ithad a non-preemptive multi-

tasking OS (up to 8 jobs)


Embedded Systems Today

James Benefer, Designing an optimal wireless SoC, EET October 11th 2004


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Embedded Systems Today (2)

Most of the components are integrated in one chip

System on a chip, SoC, with millions of transitors Can integrate analog and RF sections, and flash memories.

Only SDRAM, some passive components and power supply

are needed.

Multiprocessing:

A general purpose processor together with a DSP, and also

there might be custom co-processors (e.g. MPEG-4)

Plenty of peripherals:

General-purpose (Timers, INTC, UART) as well as specific

ones (HDD, Memory Card, Wireless, USB)

Platform-based design


Embedded Systems Are Everywhere

The average middle-class

American household has about

40 to 50 microprocessors in it

Another 10 microprocessors are

in every PC

The Mercedes S-class has 65


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Some Examples: Bluetooth

Bluetooth RF System-on-Chip: Product Design Challenges and Tradeoffs

Andreas Sibrai and Vjekoslav Matic, TechOnLine Jan. 28, 2004


Some Examples: DVD Writer


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But Do Things Have

to Be that Complex?


No! Still a Lot of Problems Can Be

Solved with 8-Bit Microprocessors


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Most Embedded Systems Are Simple

Intel just holds a 2% of the global processor market

Currently there are 40 MCU vendors, 1300 different 8-bitdevices and 240 32-bit alternatives

Plenty of problems are solved with a simple 8-bitmicrocontroller: Successful PIC and Motorola HC08 families

Low-cost and low-power, and have SoC features (a lot ofperipherals, analog sections)

Known devices, no need for learning new design flows

The best solution is not the most complex, is the onethat optimizes the tradeoff between all the differentdesign metrics


Design Metrics

Cost

Unit cost: The cost of manufacturing each unit (just the

component and assembly costs)

NRE (Non-Recurring Engineering Cost): The one-time cost

of designing the system (includes prototyping)

Performance

Most important: Ability to work in real time

Time to give a response to the user (e.g. navigation system)

Physical Constraints

Size

Power


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Design Metrics (2)

Development time

Time-to-protoype: The time needed to build a first workingversion of the system

Time-to-market: The latter time, plus the time to manufacture

the product and distribute it to the resellers

Other design issues

Flexibility: the system can be used for different tasks without

significantly increasing the NRE or the unit costs

Maintainability: the system can easily be updated and/or

repaired Fail-safe operation: Necessary in mission-critical systems,

like life support

Microcontrollers



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Definition

A microcontroller is an integrated circuit or chip that

includes the three functional units of a computer: Central Processing Unit

Memory

Input/Output and/or peripherals


Definition

Microcontrollers are usually

designed for specific applications

Price and power consumption are

important

Each application has different needs

Performance of the Central

Processing Unit

Size of memory

Peripherals



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Microcontroller vs. Microprocessor

There are several differences,

but the most important is thefunctionality

A microprocessor needs

additional components such as

memories, peripherals, etc.

A microcontroller includes all the

necessary components

No additional components are

necessary (usually) All peripherals and additional

units are included


Components of a Microcontroller


Fuente: http://o.mneina.googlepages.com/what_is_microcontroller.htm


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Memory unit Store the program instructions and

temporal data Program memory is not usually

bigger than 16 K-words of non-volatile memory

Data memory, typically SRAM, isnot usually bigger than 5 Kilobytes

Central processing unit Executes operations with memory

Executes arithmetic operations

Includes small high-speed memory

called registers Store data for arithmetic and

memory operations



Buses There are two types of buses: address

and data Address bus contains the position to

be read or write Data bus contains the data to be reador write

Input/Output units Also known as ports

There are three types of ports: Input

Output

Bidirectionals

Ports are part of the memory They can be read or write

The value of the port is the value of thepins of the port



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Timer Provides a time reference for

timing, counting, etc.

It is basically a counter

A register which value isincremented each clock cycle

Take the value before and aftera task to calculate the executiontime of the task

Very important component

Communications

Peripherals to communicate withthe outside world

Parallel, serial, USB, CAN,Ethernet, etc.



Watchdog Internal timer

Helps to detect if

If the microcontroller is stopped

The program is not workingcorrectly

Analog-Digital Converter (ADC) Outside world is usually analogic

Allows to convert analog signals todigital signals a vice versa

Microcontroller only operates withdigital values



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Microcontrollers

Vendors


Microcontrollers

Shapes



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Sistema Skybot


Skybot Descripcin

Sistema abierto para el desarrollo completo de robots

Software multiplataforma

Estructura metacrilato con dos motores de CC Sensores:

2 sensores de contacto

Hasta 4 fotodetectores

1 LDR

1 Rele

Electrnica:

CPU: Skypic (Microcontrolador PIC) Tarjeta de potencia: Sky293 (L293)



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Skybot Descripcin


Sensores de

contacto

Sensores de luz

Sensores de

infrarrojos

Skybot Ejemplos


Sigue lneas Mogolln


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CPU: Skypic Descripcin

Tarjeta entrenadora para los PIC16f87X

Contiene el PIC16f876a

Compatible con el ICD2 de Microchip

Led y pulsador de pruebas

Conexin directa de 8 servos

Hardware libre y multiplataforma

Conectores que dan acceso a todos losrecursos del microcontrolador

Dos sistemas de comunicaciones diferentes

para su interconexin con otras tarjetas, unPC o cualquier otro sistema Driver serie tipo RS-232

Bus I2C para conexin de sensores


PIC 16f876a (pines)



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La Skypic aade a este circuito:

Conversor TTL->RS232

LED de pruebas

Pulsador de pruebas

Conexin ICD2

Bus I2C

Skypic Interfaces



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Potencia: Sky293 Descripcin

Interfaces para manejar hasta 2 motoresbidireccionales o un motor paso a paso

bipolares. L293 que contiene 2 Puente-H

Interfaces para polarizar y controlar lalectura (analgico y/o digital) de hasta 4fotodetectores

Permite un sistema de alimentacin de losmotores diferente al de la lgica

Dispone de 6 entradas analgicas(Pueden ser entradas/salidas digitales y

otras 4 seales de entrada/salida digital).

Dispone de un rel


Sky293 Interfaces



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Software


Para programar el Skybot necesitamos las siguientes

herramientas:

SDCC: Compilador de C para microcontroladores PIC GPUTILS: Utilidades para microcontroladores PIC

Pydownloader: Descarga de programas a la Skypic

Skybot-test: Programa de diagnsticos para Skybot

Editor de textos para escribir los programas

Enlaces recomendados:http://www.iearobotics.com/wiki/index.php?title=Taller_Skybot:Sesi%C3%B3n_3

http://www.iearobotics.com/wiki/index.php?title=Taller_Skybot:Sesion4:Programaci%C3%B3n_del_Skybot

http://www.iearobotics.com/wiki/index.php?title=Programaci%C3%B3n_del_PIC16_en_C



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Conexin al PC

Puerto Serie

RS232-38400,8n1

En los laboratorios: COM1

Programas


Programmers Notepad: Editor - Compilador


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Programas


Skybot-test: Prueba del robotPydownloader: Descarga

Manuales y referencias

Descripcin del robot Skybot

http://www.iearobotics.com/wiki/index.php?title=Skybot

Proceso de montaje del Skybot

http://www.iearobotics.com/wiki/index.php?title=Taller_Skybot

Instalacin del softwarehttp://www.iearobotics.com/wiki/index.php?title=Taller_Skybot:Sesi%C3%B3n_3

Manuales de programacinhttp://www.iearobotics.com/wiki/index.php?title=Taller_Skybot:Sesion4:Programaci%C3%B3n_del_Skybot

http://www.iearobotics.com/wiki/index.php?title=Programaci%C3%B3n_del_PIC16_en_C

Manual de la Skypic

http://www.iearobotics.com/wiki/index.php?title=Skypic

Manual de la Sky293http://www.iearobotics.com/proyectos/sky293/sky293.html

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