Ultrasonic Tape Measure UTM

1
Ultrasonic Tape Measure (UTM)

• Group 19
• Temitayo Akinrefon -- CpE
• Erlande Janvier -- EE
• Wendy Nguyet Nguyen -- CpE
• June 17, 2002
• Advisor Dr. Samuel Richie

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What is UTM?

• The Ultrasonic Tape Measure (UTM) is a device
  that will measure distances between objects using
  ultrasonic sound (or ultrasound).

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Presentation Outline

• Project Specifications
• Key Components
• Hardware Design
• Software Design
• Administrative Tasks
• Project to Date

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Specifications Requirements

• 95 accurate
• Measurement range 2 feet to 25 feet (0.6m -
  7.6m)
• Receive and display geographical altitude input
• Measure and display temperature
• Physical dimension 6.5 x 2.5 x 1.5

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Project Limitations

• Not designed to measure object dimensions
• Not at peak performance when measuring diagonal
  distances
• Not designed to work in cluttered areas

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Key Components

• Polaroid 6500 Ultrasonic Ranging Module
• MV 8515 Micro-Controller
• Polaroid Electrostatic Transducer
• Samsung G8 Liquid Crystal Display (LCD)
• DS1620 Temperature Sensor

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How does UTM work?

• User presses the button on the UTM for
  measurement
• Initial signal of ultrasound is sent out through
  the transmitter of the transducer
• Ultrasound hits object and bounces back as ECHO,
  which is then received by the receiver of the
  same transducer
• Time of flight for transmitting and receiving
  ultrasound is then measured, calculated, and
  converted to distance measurement.

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System Block Diagram
LCD Display
Ranging Module
Transducer
Pulse Generator
Ultrasonic Transmit Transducer
Micro Controller
40 kHz Oscillator
INIT
Threshold Detector
Ultrasonic Receive Transducer
Amplifier
Comparator
ECHO
Temperature Sensor
Altitude Input
Power Supply
To All Components
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What is sound?

• Sound - Radiant energy that is transmitted in
  longitude waves that consist of compression and
  refraction in its medium
• 3 basic classes of sound
• Infrasonic-below human hearing
• Audible (20 Hz-20kHz)
• Ultrasonic above human hearing
• Encyclopedia Britannica

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Ultrasonic Sound Sound Equations

• Speed of sound through air is about 331 m/s
• Speed of sound dependent on temperature and
  altitude
• Equation of Temperature with altitude dependency
• T59-.00356h---tropospherefrom surface to
  11019.3 m
• From 11019.3 m to 25099.1 m----temperature
  remains constant
• Equation of speed with temperature dependency
• Speed 331(1T/273)0.5

www.grc.nasa.gov/www/K-12/airpaline/sound.html
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Ultrasonic Transducers

• Definition
• A device that receives energy from system and
  transmits it to another system
• Types of Ultrasonic Transducers
• Piezoelectric Transducers
• Crystal or ceramic Piezo material
• Small, efficient, used in security devices or
  signal processing devices, uses small power
• Electrostatic Transducers
• Made of nickel or alloy material
• Handle high power devices, ultra sensitive, used
  for detecting soft objects, large target range.

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Ultrasonic Transducers

• 50kHz Electrostatic air transducer from Polaroid
• Bi-functional
• Cost-efficient
• Used commercially in mass quantities
• Beam output is more concentrated

With Acronames permission
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Polaroid 6500 Ranging Module

• Features
• Accurate Sonar Ranging from 6 inches to 35 feet
• Drives 50-kHz Electrostatic Transducer with No
  Additional Interface
• Operates from Power Supply of 4.5 6.8 Vdc
• Accurate Clock Output Provided for External Use
• Selective Echo Exclusion
• Multiple Measurement Capability
• Uses TI TL851 and SN28784N Sonar Ranging
  Integrated Circuits
• Convenient Terminal Connector
• Variable Gain Control Potentiometer

Dimension 2.222 x 1.778
With Acronames permission
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How Ranging Module Works

• Generates the drive signal for the transducer
• Controls timing functions
• Receives, amplifies and filters the returning
  echo
• Processes the signal and provides a TTL output
  when the echo returns
• Measures the elapse time between INIT and ECHO
  return

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Polaroid Ranging Module Schematic
With Acronames permission
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Functional Block Diagram of TL851
With Polaroids permission
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Schematic of The SN28784N
With Polaroids permission
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Example of Single-Echo-Mode Cycle without
Blanking Input
With Acronames permission
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Example of Multiple-Echo-Mode Cycle with Blanking
Input
With Acronames permission
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Testing Result for Ranging Module and Transducer
Interfaced with Microcontroller

• Ranging module works well
• Ping can be heard and ranging values varies when
  pointing transducer to different objects with
  different distances.
• Working on algorithm in software for accurate
  measurement

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DS1620 Temperature Sensor

• Features
• Requires no external components
• Supply voltage range from 2.7V to 5.5V
• Measures temperature from
• -55C to 125C in 0.5C increments (-67F to
  257F in 0.9F increments)
• 9-bit value temperature reading
• Converts temperature to digital word in 1 second
  (max)
• Thermostatic settings are user-definable and
  nonvolatile
• Data is read from/written via a 3-wire serial
  interface (CLK, DQ, RSTLOW)
• Applications include thermostatic controls,
  thermometers, and other thermally sensitive
  systems

With Dallas Semiconductors permission
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Samsung G8 Liquid Crystal Display

• 16 char x 2 line LCD.
• Module size 4.85" x 1.7."
• Display size 3.67" x 1.05."
• Input through 16 pin male header, 2 x 8 pins on
  0.1" centers.
• LED backlight operates on 5 Vdc.

Used with permission from all electronics Corp.
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LCD Display Testing

• Parts used in testing LCD display
• d.i.l switch
• toggle switch
• momentary action switch
• potentiometer
• several 4.7Kohm resistors

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LCD Display Testing

• Reprinted with permission from Everyday Practical
  Electronics

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MV 8515 Microcontroller

• ATMEL family
• Similar to BASIC stamp
• 512 bytes EEPROM
• Runs 10xs faster than the PIC Z80 or 8051 type
  controllers
• RS 232 port used -- Special development kits are
  not required
• Intended for small, low-end applications
• Endurance 100,000 Write/Erase Cycles
• Single Clock Cycle per Instruction
• 32 x 8 General Purpose Working Registers
• One 8-Bit Timer/Counter with Separate Prescaler
• One 16-Bit Timer/Counter with Separate Prescaler
• Low Power Idle and Power Down Modes
• Built-in BASIC interpreter

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MV 8515 Microcontroller
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Software Design Overall

• PBASIC
• Software compiling used DOS via RS-232
• Major functions in our program

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Flowchart
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Flowchart
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Distribution of Work

• Erlande Janvier
• Ultrasonic transducers
• LCD display
• Hardware interface

• Wendy Nguyen
• Ranging module
• Temperature sensor
• Software/Hardware interface

• Temi Akinrefon
• MV8515 Microcontroller
• Software interface
• Power Supply

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Administrative Tasks Milestone Chart
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Administrative Tasks Budget Financing
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Difficulties

• Changing the design once
• Getting started on the coding
• Weve tested the parts and now will start coding
  and interfacing

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Conclusions Project to Date

• Hardware acquisition 100
• Hardware design 50
• Hardware interfacing
• Software design 80
• Software composition 20
• Currently writing code
• Total project completion 45

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Questions or Comments?