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Lecture 1: Introduction to Microprocessors

Dr. Ying (Gina) Tang Electrical and Computer Engineering Rowan University

ECE342 Digital II

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What is a microprocessor

Informally, a microprocessor (µP) is the “brain” of a computer that has been implemented on one semiconductor chip

Precisely, a microprocessor (µP) is a single-chip CPU for a programmable computer

Prof. Ying (Gina) Tang

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The Microprocessor Age

The microprocessor became possible only after integrated circuit technology had advanced to the point where several thousand transistor switches could be integrated onto single semiconductor “chip”

Prof. Ying (Gina) Tang

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Advantages of Microprocessors

Programmability

Performance

Sophisticated functions can be provided relatively easily in software

Reliability

Advances in integrated circuit technology leads to faster and more powerful microprocessors

Integrated circuits are highly-reliable and solid state devices.

Compactness

Prof. Ying (Gina) Tang

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Limitations of Microprocessors

Limitations

Glue logic (e.g., address decoder and buffer chips) required to interface with the memory chips

External memory chips needed to hold program and data

Peripheral chips needed to interface with I/O devices

Prof. Ying (Gina) Tang

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Embedded Processor What make a processor an embedded processor A microprocessor used in an embedded system

that is not a general-purpose computer

Prof. Ying (Gina) Tang

Systems range from using 4-bit to 128-bit CPUs.

Programming languages range from assembly language to higher level object oriented languages.

Complex systems typically run a embedded OS or a lite desktop OS.

CPU clock speeds can range from kHz to GHz.

Packages from 6 pins to 1000+ pins.

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Anatomy of a Microcontroller Essential Components of a Microcontroller :

the processor and peripheral functions

Prof. Ying (Gina) Tang

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Different Peripherals Timers The time at which transitions occur on an

input can be recorded Outputs can be driven on and off

automatically at a specified frequency They provide a regular “tick” that can be

used to schedule tasks in a program

Prof. Ying (Gina) Tang

Anatomy of a Microcontroller

Watchdog Timer A safety feature that resets the processor if

the program stuck in an infinite loop

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Different Peripherals (cont.)

Anatomy of a Microcontroller

Communication interfaces Integrated Circuit (I2C) Universal Synchronous/Asynchronous

Receiver/Transmitter (USART) RS232 A/D and D/A Real Time Clock Track the time of day Data loggers

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Architectures Harvard Architecture:

von Neumann Architecture

Microchip PIC; Intel 8051

MSP430; ARM7

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Data representation Number systems Integer storage sizes

Ranges of unsigned integers

8 16

32 64

byte word

doubleword quadword

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Data representation Number systems Storage sizes and ranges of signed

integers

Two’s complement Question: what are the 2’s complement representations of 8d and –8d in 8-bit binary?

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Data representation Conversion Convert binary/hex/oct to decimal

(Number)n

= ∑(multiply each digit by an integer power of n)

Convert decimal to binary/hex/oct For a decimal integer - successive division by n - accumulation of the remainders For a decimal fraction - successive multiplication by n - accumulation of the integer digits

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Data representation Your turn….Conversion Problems

(0.6875)10=(_________)2

(1.234)5 = (________)10 45677h = (________)8 -38d = (________)h

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Data representation Character Storage 7-bit /8-bit ASCII

16-bit Unicode: http://www.unicode.org

Format Value

ASCII binary "01000001"

ASCII decimal "65"

ASCII hexadecimal "41"

ASCII octal "101"

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Data representation Real Numbers – floating-point numbers Floating-point numbers are expressed as a

number (Significand) multiplied by a constant (base) raised to some integer power (exponent).

e.g., the floating-point notation for decimal number +6123.78 is: +.612378x104

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Sign: plus or minus Significand S Exponent E

This number can be stored in a binary word with three field:

The base B is implicit and need not be stored because it is the same for all numbers

A normalized number: one in which the most significant digit of the significand is nonzero.

Data representation Floating-point numbers can be taken with

binary numbers in the form: EBS ±×±

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IEEE Floating-point Standard

For base 2 representation, a normalized number is one in which the most significant bit of the significand is one: Ebbbb ±×± 2....1

Since the most significant bit is always one, it is unnecessary to store this bit, which is called the hidden bit.

Biased exponent: a constant called excess number is added to the actual exponent so that the biased exponent is always a positive number.

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IEEE Floating-point Standard Two most common formats of IEEE floating-

point representations (+/- S x B+/-E)

Sign Biased exponent (E) Significand/mantissa/fraction (S) 1 bit 8 bits 23 bits

Single precision (the bias is 127d)

1 bit 11 bits 52 bits

Double precision ( the bias is 1023) Sign Biased exponent (E) Significand/mantissa/fraction (S)

Hidden bit

Hidden bit

In decimal In binary 1.5 x 2-126 0 00000001 10000000000000000000000 -1.5 x 2126 1 11111101 10000000000000000000000

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IEEE Floating-point Standard Note that we are not representing more

individual values with floating-point notation. What we have done is to spread those numbers out in two ranges, positive and negative. The number in floating-point notation are not

spaced evenly along the number line as are fixed-point numbers.

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The number infinity is stored as all ones in the exponent and all zeros in the mantissa. The sign bit indicates either a positive or a negative infinity

IEEE Floating-point Standard

The number 0.0 is stored as all zeros. The sign bit indicates either a positive or a negative zero.

Two exceptions

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Focus of This Course

Prof. Ying (Gina) Tang

Embedded systems without an OS

16 bit processors

Embedded software in C

Software patterns & tricks Embedded hardware overview

Peripheral usage

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Development Hardware

TI MSP430F5529 Launchpad 16-bit processor w/ 128 KB flash Integrated USB and PHY, supporting USB 2.0 Hardware multiplier 2 university serial communication interfaces DMA (direct memory access) 12-bit A/D 63 I/O pins

4 16-bit timers Real time clock

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Development Hardware (cont.)

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Development Software Code Composer Studio 6 An integrated development environment

(IDE) with A suite of tools used to develop and debug

embedded applications Compilers for each of TI's device families Source code editor12-bit A/D Project build environment Debugger Simulators Free in a special “16KB code-limited”! Available

at http://www.ti.com/tool/ccstudio-msp