Ultrasonic Tape Measure Group 19

1
Ultrasonic Tape MeasureGroup 19

• Temitayo Akinrefon
• Erlande Janvier
• Wendy Nguyet Nguyen
• July 22, 2002
• Advisor Dr. Samuel Richie

2
What is UTM?

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

3
Presentation Outline

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

4
Specifications Requirements

• 95 accurate
• Measurement range 2 feet to 25 feet (0.6m -
  7.6m)
• Physical dimension 6.5 x 2.5 x 1.5
• Receive and display geographical altitude input
• Measure and display temperature
• Not designed to measure object dimensions
• Not at peak performance when measuring diagonal
  distances
• Not designed to work in cluttered areas

5
Research
6
What is sound?

• Sound - Radiant energy that is transmitted in
  longitudinal 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

7
What Affects Sound?

• Two factors that affect sound
• Altitude
• Temperature
• Speed of sound is directly dependent on
  temperature and altitude
• altitude inversely proportional temperature (to
  a point)
• temperature is directly proportional Vsound

8
Sound Equations Altitude Temperature

• Three atmospheres
• Troposphere
• Lower Stratosphere
• Upper Stratosphere
• In most climates, altitude will determine
  temperature and temperature will determine speed
  of sound
• Equation of temperature with altitude dependency
• From surface to 11019.3 m T59-.00356h---troposp
  here
• 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/airplane/sound.html
9
Sound Equations Altitude Temperature

• Altitude has no great effect on sound waves in
  the troposphere

In total the final decrease in speed in the
troposphere is 12
10
Sound Equations Altitude Temperature

• Since there is no need to account for altitude,
  there is no need to use first equation.
• Equation of speed with temperature dependency is
  useful
• Air conditioning
• Drastic regional climate differences (ie.
  Florida)

11
Original System Block Diagram
LCD Display
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
12
Piezo Transducers

• Types of Ultrasonic Transducers
• Piezoelectric Transducers
• Electrostatic Transducers

13
555 Timer Pulse

• Pulse
• Dinput causes the output to increase from 0 to
  Vcc
• Holds Vcc for a moment
• The output dissipates to 0

14
555 Timer Oscillation

• Oscillation
• series of pulses

15
555 timer Pulse and Oscillation
Reprinted From Iguana Labs
Reprinted From Iguana Labs
Pulse
Oscillation
Output
Output
VCC
VCC
Time
Time
16
Varitronix S16264 Liquid Crystal Display

• Display size 1.91" x 0.48
• Module size 2.6" x 1.46"
• Character size 0.16" x 0.1
• 16 pin serial input
• 5 x 8 dot format
• Blue digits on light blue (near white)
  background.

Used with permission from all electronics Corp.
17
LCD Display Testing

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

18
LCD Display Testing

• Reprinted with permission from Everyday Practical
  Electronics

19
MV 8515 Microcontroller

• AVR family
• ATMEL 8515 Built-in BASIC interpreter
• 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
• 32 x 8 General Purpose Working Registers

20
MV 8515 Microcontroller
Reprinted from http//www.akizuki.ne.jp/ashop/atm
el-dev.htm
21
MV 8515 Microcontroller
Ranging Module
Temperaure Sensor
LCD
22
LCD Test Code

• Used port C and Port A (3 bits)
• 8-bit function
• Two line, non scrolling input
• Subroutine used to trigger the enable line

23
Temperature Sensor Ranging ModuleTest Code

• Temperature Sensor
• Used port A (3 pins)
• Toggle function makes it possible
• Had difficulties programming TLow and Thigh
• Ranging Module
• Used Port B
• Only 2 Pins are needed for ranging module to work

24
Key ComponentsHardware Design
25
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.

26
Revised System Block Diagram
LCD Display
Ranging Module
Pulse Generator
Ultrasonic Transmit Transducer
Micro Controller
40 kHz Oscillator
INIT
Ultrasonic Receive Transducer
Amplifier
Filter
ECHO
Temperature Sensor
Power Supply
To All Components
27
Key Components

• Polaroid 6500 Ultrasonic Ranging Module
• BasicStamp2e Micro-Controller
• Polaroid Ultrasonic Transducer
• SEE-BPI-216 Liquid Crystal Display (LCD)
• DS1620 Temperature Sensor
• Parallax Carrier Board

28
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
Permission pending from Acroname, Inc.
29
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

30
Polaroid Ranging Module Schematic
With Acronames permission
31
Functional Block Diagram of TL851
With Polaroids permission
32
Schematic of The SN28784N
With Polaroids permission
33
Example of Single-Echo-Mode Cycle
With Acronames permission
34
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) in every second
• Converts temperature to digital word in 1 second
  (max)
• 9-bit data reading
• 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
35
Temperature Measuring Circuitry
With Dallas Semiconductors permission
36
SEE-BPI216 Liquid Crystal Display

• 2 lines x 16 chars LCD
• Display size 13.8 x 64.5 mm
• Supply Power of 4.8 to 5.2Vdc at 3mA
• Connector pinout
• 5 GND SER GND 5
• Serial input RS-232 at 2400 or 9600 baud rate

Dimension 36 x 80 mm
With Scott Edwards Electronics permission
37
BPI-216 LCD Backpack
With Scott Edwards Electronics permission
38
Positioning the Cursor on LCD
0 1 2 3 4 5 6 7 8
9 10 11 12 13 14 15
LINE 1 LINE 2
To position the cursor, use the
instruction-prefix byte, ASCII 254, followed
by the set-position byte value. Example
lt254gtlt196gt will move the cursor to line 2,
character 4.
39
BS2e Microcontroller
Dimension 1.2 in x 0.62 in

• 24 pin DIP Module
• Combination of surface mount components including
  Scenix SX28AC/SS
• 16K bytes of EEPROM
• 32 bytes of RAM
• 20MHz/4,000 instructions per second
• 4,000 lines of PBASIC code
• RS 232 serial port source code downloaded via
  this port

With Parallaxs permission
40
BS2e Microcontroller Schematic
With parallaxs permission
41
Software Design Algorithm
42
Software Design and Algorithm

• PBASIC language
• Source code run and downloaded via RS-232 port
• Algorithm
• Since temperature has some influence on speed of
  sound, temperature is taken into account for
  calculation of the distance measurement

43
Software Design and Algorithm

• Equation used for speed of sound depending on
  temperature
• v 331 ?T/273 m/sec
• (where T is in Kelvin and T C 273.15)
• Timer uses 500KHz clock frequency (2usec per
  clock tick)
• Max range of ranging module is 35 feet 420
  inches, roundtrip 840 inches

44
Software Design and Algorithm

• Equation for conversion factor
• 840 (time that sound travels 1 in) / 2usec
• of ticks at max range
• convfac (ticks/in) of ticks at max range /
  420
• Equation for distance
• d (echo time offset time) / convfac

45
Software Design and Algorithm

• DS1620 only reads temperature in C. Conversion
  to F is implemented in code
• F (C 1.8) 32
• Code is written to allow temperature sensor to
  read temperature every second.
• Display new readings of temperature and distance
  measurement every second

46
Administrative Tasks
47
Distribution of Work

• Erlande Janvier
• Sound equations and research
• Ultrasonic transducers
• Temperature sensor

• Wendy Nguyen
• Ranging module
• Temperature sensor
• Software/Hardware interface
• LCD interface
• Basic Stamp 2e research and implementation

• Temi Akinrefon
• MV8515 Microcontroller
• Software interface

48
Milestone Chart
49
Budget Financing
50
Difficulties

• Not on the same page
• Different goals for the project
• Different definitions of group work, individual
  work, original work
• Changing the design once
• Improper communication

51
Questions or Comments?