BODY COMPUTERS

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BODY COMPUTERS

• CHAPTER 12

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OBJECTIVES

• ANALOG AND DIGITAL VOLTAGE SIGNALS
• COMPUTER COMMUNICATION
• COMPUTER MEMORY
• INPUTS
• OUTPUTS
• MULTIPLEXING

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COMPUTER FUNCTIONS

• FOUR PRIMARY FUNCTIONS
• INPUT
• PROCESSING
• DATA STORAGE
• OUTPUT

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ANALOG VS. DIGITAL
C370
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COMPUTERS ONLY UNDERSTAND ON OR OFF

• MUST BE DIGITAL INPUT
• BINARY SYSTEM
• SIGNAL CONVERSION
• LOGIC GATES

FIG 12-3 CLASS
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PROCESSOR OPERATION
FIG 12-5 CLASS
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COMPUTER MEMORY

• READ ONLY MEMORY (ROM)
• RANDOM ACCESS MEMORY (RAM)
• KEEP ALIVE MEMORY (KAM)
• PROGRAMMABLE READ ONLY MEMORY (PROM)
• ERASABLE PROM (EPROM)
• ELECTRICALLY ERASABLE (EEPROM)
• NONVOLATILE RAM (NVRAM)

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SIGNAL CONVERSION
FIG 12-6 CLASS
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INPUTS

• PROCESSOR ONLY UNDERSTANDS DIGITAL INPUT
• TYPES OF SENSOR INPUTS
• PRESSURE
• TEMPERATURE
• MECHANICAL MOVEMENT
• VOLTAGE GENERATORS
• SWITCHES

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THERMISTORS
FIG 12-24 C

• TEMPERATURE SENSITIVE SEMI-CONDUCTOR
• NTC - LOWERS RESISTANCE WHEN HIGHER TEMPERATURE
• PTC - INCREASES RESISTANCE WHEN HIGH TEMPERATURE

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WHEATSTONE BRIDGE

• USED TO SENSE PRESSURE OR TEMPERATURE
• FOUR RESISTORS IN PARALLEL
• PROCESSOR MEASURES VOLTAGE DROP

12-25
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PIEZOELECTRIC DEVICES

• CONVERTS VIBRATION OF CRYSTAL INTO SIGNAL TO PCM
• VOLTAGE GENERATOR
• PCM SEES FREQUENCY SIGNAL

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PIEZORESISTIVE DEVICES

• ACTS LIKE A VARIABLE RESISTOR
• REGULATED VOLTAGE
• PRESSURE CHANGES VOLTAGE DROP

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POTENTIOMETERS

• MEASURES MOVEMENT
• WIRE WOUND RESISTOR
• MODIFIES REFERENCE VOLTAGE
• THREE WIRE

12-26 C
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MAGNETIC PULSE GENERATOR

• MEASURES SPEED AND POSITION
• AC ANALOG
• RELUCTOR INTERRUPTS MAGNETIC FIELD
• PCM AMPLIFIES SIGNAL

12-29
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PULSE SIGNAL WAVE FORM
FIG 12-27 C
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HALL-EFFECT SWITCHES

• SEMI-CONDUCTOR
• SHUTTER WHEEL
• PERMANENT MAGNET
• SCHMITT TRIGGER
• DIGITAL SIGNAL

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VOLTAGE GENERATOR

• FEEDBACK SENSOR
• ZIRCONIUM DIOXIDE
• VOLTAGE VARIES WITH OXYGEN CONTENT

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OUTPUTS (ACTUATORS)

• CONVERTS ELECTRICAL SIGNAL INTO MECHANICAL ACTION
• OUTPUT DRIVER IN PCM
• MOTORS
• SOLENOIDS
• DISPLAYS
• RELAYS

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MULTIPLEXING

• SINGLE CABLE TO TRANSMIT MULTIPLE SIGNALS
• MUX SIGNAL IS DIGITAL
• PROCESSES ONE SIGNAL AT A TIME

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