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Embedded Systems Technology - Custom single-purpose processors Appunti scolastici Premium

Processor is a:
– digital circuit that performs computation tasks;
– controller and datapath.
Its general-purpose is variety of computation tasks, its single-purpose is one particular computation task. A custom single-purpose ia a non-standard task.
A custom single-purpose processor may... Vedi di più

Esame di Sistemi embedded docente Prof. L. Pomante

Anteprima

ESTRATTO DOCUMENTO

Embedded Systems Design: A Unified

Hardware/Software Introduction

Chapter 2: Custom single-purpose

processors 1

Outline

• Introduction

• Combinational logic

• Sequential logic

• Custom single-purpose processor design

• RT-level custom single-purpose processor design

Embedded Systems Design: A Unified 2

Hardware/Software Introduction, (c) 2000 Vahid/Givargis 1

Introduction

• Processor

– Digital circuit that performs a

computation tasks Digital camera chip

– Controller and datapath CCD

– General-purpose: variety of computation CCD Pixel coprocessor D2A

tasks A2D preprocessor

– Single-purpose: one particular lens

computation task JPEG codec Microcontroller Multiplier/Accum

– Custom single-purpose: non-standard

task DMA controller Display

ctrl

• A custom single-purpose

processor may be Memory controller ISA bus interface UART LCD ctrl

– Fast, small, low power

– But, high NRE, longer time-to-market,

less flexible

Embedded Systems Design: A Unified 3

Hardware/Software Introduction, (c) 2000 Vahid/Givargis

CMOS transistor on silicon

• Transistor

– The basic electrical component in digital systems

– Acts as an on/off switch

– Voltage at “gate” controls whether current flows from

source to drain source

– Don’t confuse this “gate” with a logic gate gate Conducts

if gate=1

1 drain

gate

oxide

IC package IC source channel drain Silicon substrate

Embedded Systems Design: A Unified 4

Hardware/Software Introduction, (c) 2000 Vahid/Givargis 2

CMOS transistor implementations

• Complementary Metal Oxide source

source

Semiconductor gate Conducts

gate Conducts if gate=0

if gate=1 drain

drain

• We refer to logic levels pMOS

nMOS

– Typically 0 is 0V, 1 is 5V

• Two basic CMOS types

– nMOS conducts if gate=1 1 1 1

x x

y

– pMOS conducts if gate=0 x F = x' y

F = (xy)'

– Hence “complementary” x F = (x+y)'

y

0 x y

• Basic gates 0 0

– Inverter, NAND, NOR NOR gate

inverter NAND gate

Embedded Systems Design: A Unified 5

Hardware/Software Introduction, (c) 2000 Vahid/Givargis

Basic logic gates

x x

x

x x F x y y y

x x

F F F

F F F

F y

0 0 0 0 0 0 0 0 0

0 0

y y

1 1 0 1 0 0 1 1 0 1 1

1 0 0 1 0 1 1 0 1

F = x y F = x + y

F = x F = x y

1 1 1 1 1 1 1 1 0

AND OR

Driver XOR

x F x

y y y

x x

x x

x F F F

x F F F

F

0 0

1 0 1 0 1 0 1

0 0

y y

y

1 0 0 1 1 0 1 0 0 1 0

1 0 1 1 0 0 1 0 0

F = x y

F = (x y)’ F = (x+y)’

F = x’ 1 1 0 1 1 0 1 1 1

XNOR

NAND NOR

Inverter

Embedded Systems Design: A Unified 6

Hardware/Software Introduction, (c) 2000 Vahid/Givargis 3

Combinational logic design

A) Problem description B) Truth table C) Output equations

Outputs

Inputs y = a'bc + ab'c' + ab'c + abc' + abc

y is 1 if a is to 1, or b and c are 1. z is 1 if a b c y z

b or c is to 1, but not both, or if all are 1. 0 0 0 0 0

0 0 1 0 1 z = a'b'c + a'bc' + ab'c + abc' + abc

0 1 0 0 1

0 1 1 1 0

1 0 0 1 0

1 0 1 1 1

1 1 0 1 1

D) Minimized output equations 1 1 1 1 1

y E) Logic Gates

bc 00 01 11 10

a 0 0 0 1 0 a y

1 1 1 1 1 b

c

y = a + bc

z bc 00 01 11 10

a 0 0 1 0 1 z

1 0 1 1 1

z = ab + b’c + bc’

Embedded Systems Design: A Unified 7

Hardware/Software Introduction, (c) 2000 Vahid/Givargis

Combinational components A B

I0

I(log n -1) A B A B

I1 I0

I(m-1) n

n

… n n n

n … n bit,

log n x n n-bit n-bit

S0 n-bit, m x 1 S0

m function

Decoder Adder Comparator

… Multiplexor ALU …

… n

S(log m) S(log m)

n

n O(n-1) O1 O0 sum

carry less equal greater

O O

O = less = 1 if A<B O = A op B

O0 =1 if I=0..00 sum = A+B

I0 if S=0..00 equal =1 if A=B op determined

O1 =1 if I=0..01 (first n bits)

I1 if S=0..01 greater=1 if A>B by S.

… carry = (n+1)’th

… O(n-1) =1 if I=1..11 bit of A+B

I(m-1) if S=1..11 

With enable input e With carry-in input Ci May have status outputs

all O’s are 0 if e=0 carry, zero, etc.

sum = A + B + Ci

Embedded Systems Design: A Unified 8

Hardware/Software Introduction, (c) 2000 Vahid/Givargis 4

Sequential components

I

n

load shift n-bit

n-bit n-bit Counter

Register Shift register

I Q

clear n

n Q

Q Q = lsb

Q = Q =

- Content shifted

0 if clear=1, 0 if clear=1,

- I stored in msb

I if load=1 and clock=1, Q(prev)+1 if count=1 and clock=1.

Q(previous) otherwise.

Embedded Systems Design: A Unified 9

Hardware/Software Introduction, (c) 2000 Vahid/Givargis

Sequential logic design

A) Problem Description C) Implementation Model D) State Table (Moore-type)

You want to construct a clock x

divider. Slow down your pre- a Outputs

Inputs

Combinational logic

existing clock so that you output a Q1 Q0 a I1 I0

I1 x

1 for every four clock cycles 0 0 0 0 0

I0 0

0 0 1 0 1

0 1 0 0 1 0

Q1 Q0 0 1 1 1 0

1 0 0 1 0 0

B) State Diagram 1 0 1 1 1

State register 1 1 0 1 1 1

x=1

x=0 a=0

a=0 1 1 1 0 0

I0

I1

0 3

a=1

a=1 a=1 • Given this implementation model

1 2

a=1 a=0

a=0 x=0

x=0 – Sequential logic design quickly reduces to

combinational logic design

Embedded Systems Design: A Unified 10

Hardware/Software Introduction, (c) 2000 Vahid/Givargis 5

Sequential logic design (cont.)

F) Combinational Logic

E) Minimized Output Equations

Q1Q0

I1 01

00 11 10

a a

0 0 0 1 1 x

I1 = Q1’Q0a + Q1a’ +

Q1Q0’

1 0 1 0 1

Q1Q0

I0 I1

00 01 11 10

a 0 0 1 1 0 I0 = Q0a’ + Q0’a

1 1 0 0 1 I0

x Q1Q0

00 01 11 10

a x = Q1Q0

0 0 0 1 0 Q1 Q0

1 0 0 1 0

Embedded Systems Design: A Unified 11

Hardware/Software Introduction, (c) 2000 Vahid/Givargis

Custom single-purpose processor basic

model …

external external

control controller datapath

data

inputs inputs

… … registers

datapath next-state

control and

controller datapath

inputs control

logic

datapath functional

control state units

outputs register

… …

external external

control data

outputs outputs …

a view inside the controller and datapath

controller and datapath

Embedded Systems Design: A Unified 12

Hardware/Software Introduction, (c) 2000 Vahid/Givargis 6


PAGINE

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101.95 KB

AUTORE

Atreyu

PUBBLICATO

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DESCRIZIONE DISPENSA

Processor is a:
– digital circuit that performs computation tasks;
– controller and datapath.
Its general-purpose is variety of computation tasks, its single-purpose is one particular computation task. A custom single-purpose ia a non-standard task.
A custom single-purpose processor may be:
– fast, small, low power;
– but, high NRE, longer time-to-market, less flexible.


DETTAGLI
Corso di laurea: Corso di laurea magistrale in ingegneria delle telecomunicazioni
SSD:
Università: L'Aquila - Univaq
A.A.: 2011-2012

I contenuti di questa pagina costituiscono rielaborazioni personali del Publisher Atreyu di informazioni apprese con la frequenza delle lezioni di Sistemi embedded e studio autonomo di eventuali libri di riferimento in preparazione dell'esame finale o della tesi. Non devono intendersi come materiale ufficiale dell'università L'Aquila - Univaq o del prof Pomante Luigi.

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