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Depth Finder 600. EE 595 Capstone Design Project Fall 2007 Team 3. Team #3: Group Members. Expertise: Digital: PLD/FPGA VHDL Experience: Associate Applications Engineer @ Rockwell Expertise: Microprocessors Experience: Part Time Design Engineer @ Bucyrus
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Depth Finder 600 EE 595 Capstone Design Project Fall 2007 Team 3
Team #3: Group Members • Expertise: Digital: PLD/FPGA VHDL Experience: Associate Applications Engineer @ Rockwell • Expertise: Microprocessors Experience: Part Time Design Engineer @ Bucyrus • Expertise: Management Skills Experience: Soldering, Hands-On • Expertise: Calibration, C++ Programming Experience: Engineering Intern @ Johnson Controls • Expertise: PDP, Reliability Experience: Systems Engineer @ Baxter Health Care • Adam Davis • Tony Johnson • Peter Meyer • Isaac Krull • Joe Reisinger
Depth Finder • This product will measure the depth of water. • This product uses a power supply, receiver, transmitter, microprocessor and user interface. • This application specific design will relieve the end user of difficult and hard to understand interfaces while still maintaining reliability for marine applications • This system will use a 12VDC power supply designed for marine use or 8 D Cell batteries. • This is a relatively simple design with 5 separate blocks. It utilizes our strengths as a team while still delivering key concepts learned in our academic career.
Performance Requirements • Functions and Capabilities • Product must be accurate to depths of +/- 5 percent of actual depth @ 60°F -Depth in Meters must be accurate to depths of +/- 5 percent of actual depth • Product must be able to measure depths from 2 to 50 feet -Product must be able to measure depths from 1 to 15 meters • Product must read depth continuously • Must be able to sense under the transducer within a 15 degree cone • Must be able to work both with marine batteries and with D cell batteries • Product must be able to differentiate small objects from the bottom of the lake
Performance Requirements • Modes of Operation • The Product shall be able to turn on and off • Power Inputs • The battery must be able to last for 5 hours on full operation without recharge • The product must be able to operate on a standard 12 V marine battery • The product must be able to operate on 8 standard D Cell batteries • Electrical Functions • The product must be able to operate within a voltage range of 10-14.8V • Operator I/O Inputs • The On/Off switch must be a momentary off pushbutton switch • The Feet/Meter switch must be a momentary off pushbutton switch • The Feet/meter display must be a 7 segment LED. • The display must be 0.75 in by 1.48 in. • The display must be readable up to 5 feet. • Mechanical Interfaces • The product must be able to mount onto an L bracket
Standard Requirements • Environment & Safety • The product shall be able to operate in temperatures between 0 and 55 degrees Celsius • The product shall be able to operate in 0-90% non-condensing humidity • The product shall be able to operate in altitude ranges from sea level to 8000 feet • The product shall be able to be stored in temperature ranging from -6 to 65 degrees Celsius • The product shall be able to be stored in 0-90% non-condensing humidity • The product shall be able to be stored in altitudes ranging from -500 to 60000 feet • The product shall be able to be stored without operation for 10 years • The product must be able to be immersed in water for no more than 5 seconds and still be able to operate correctly. • In the event of submersion for longer than 5 seconds, the device shall fail in a manor as to not cause bodily injury.
System - Std Reqs: Market & Business Case RequirementUnits to Specify • Humminbird, Lowrance, Eagle, Garmin. • 10M • $150 • USA and Canada • 14- up, Male and Female • Marine • $57 • $67 • 10000 Units/yr • Competitors • Market Size • Average List Price • Market Geography • Market Demography • Intended Application • Material Cost • Manufacturing Cost • Annual Volume
Refined Block Diagram Key Power Analog Signal Ping Signal Push Button #1 Push Button #2 LED Display Backlight for label Control Ultrasonic Transmitter 9 V Peter Vcc=9 V Power Source 10 – 14.8 V Joe Ultrasonic Receiver 5, 9 V Isaac CPLD 5V Adam Vcc = 5 V Vcc = 9 V Vcc=5 V User Interface 5 V Tony
Ethical/Societal Issues • Our depth finder is at risk of electrical faults and possible electrocution if proper procedures to eliminate these risks are not taken. • Our unit will need to be enclosed in a waterproof enclosure. • Proper safety grounds must also be implemented. • These actions will greatly reduce the risk of possible electrical faults or electrocution. • The engineering of our sonar transmitter and receiver is the most critical part of our product. • If this isn’t functioning 100% correct, the product will be useless. • To ensure this area of engineering is 100% correct numerous extensive tests will be performed on the transmitter and receiver components.
Applicable Patents Name: Portable Fish Finder Patent Number: 6791902 Date: September 14, 2004 • This patent could be designed around if we intended our unit to be permanently used on a boat and not portable. A different mounting device other than a suction cup could be used to mount the transducer to the boat. Name: Method for determining depth values of a body of waterPatent Number: 5465622 Date: November 14, 1995 • This patent could be designed around by omitting the velocity sensor used and assume the velocity of the sound signal to be relatively constant. For averages lakes, the velocity will not vary greatly with the change in depth. The depth our depth finder is designed for won’t be affected by changing velocity due to depth. Name: Depth Finder having variable measurement capabilitiesPatent Number: 5065371 Date: November 11, 1991 • This patent could be designed around by utilizing a different display than a liquid crystal display. A typical CRT display or LED display could be used instead. Also, our depth finder would be designed for use in fresh water only.
Burns from Hot, Touchable Surfaces • Mitigation Design/Devices/Materials/Packaging • In the event of failure, the battery and power supply shall be isolated from the user with some sort of protective cover. • Affected Blocks • Power Supply • Test(s) Required to Verify Protection • Continuous use and thermal testing
Unsafe Single Point/Device Failures • Mitigation Design/Devices/Materials/Packaging • In case of device failure, an audible alarm will sound • Materials shall be of non-corrosive, thermal treated material • Affected Blocks • User Interface, Transducer, CPLD • Test(s) Required to Verify Protection • Induce a failure during normal operation • Conduct environmental testing on prototype materials
Electric Shock • Mitigation Design/Devices/Materials/Packaging • The user interface will be isolated by using dielectric materials. • Grounding and low potential at all conductive surfaces. • Insulation of high voltages • Affected Blocks • User interface • Power Supply • Transducer Circuit • Test(s) Required to Verify Protection • Electrostatic Discharge Testing to 15kV • Surface voltage potential sensing at all high voltage contained components
Abusive Or Unknowing Users • Mitigation Design/Devices/Materials/Packaging • Utilize warning labels on the device and user manual to not allow children to use the device. • Design a carrying case which is lockable to prevent unwanted use by children. • Allow the operation of push buttons at required time intervals throughout the use of the CPLD/software • Affected Blocks • CPLD • Test(s) Required to Verify Protection • Random button pushing
Sharp Edges & Pinch Points • Mitigation Design/Devices/Materials/Packaging • All corners and edges will be rounded. Warning indications will be documented in the user manual and near any trouble spots. • The battery cable will consist of pinch proof connectors. Also, the user interface will consist of push buttons rather than switches. • Affected Blocks • User Interface, Power supply • Test(s) Required to Verify Protection • Physical inspection
Magnetic Field Energy • Mitigation Design/Devices/Materials/Packaging • Twisted shielded cables • Affected Blocks • Transmitter and Receiver • Test(s) Required to Verify Protection • Magnetic Field Immunity
Electro-Static Discharge • Mitigation Design/Devices/Materials/Packaging • Electronic shielded enclosures • Ground coupled user inputs • Affected Blocks • User Interface • Test(s) Required to Verify Protection • ESD Immunity Test
RF Electric Field Energy • Mitigation Design/Devices/Materials/Packaging • RF shielded signal cables • Affected Blocks • Transmitter, Receiver, CPLD • Test(s) Required to Verify Protection • RF Conducted Immunity
Interference with Other Electronic Systems • Mitigation Design/Devices/Materials/Packaging • Fuse to isolate power supply • Affected Blocks • Power Supply • Test(s) Required to Verify Protection • Power Surge Immunity Test
Block Description and Purpose SlidePower Supply • The power supply will consist of a battery pack containing 8 D-cell batteries. Also, it will be capable of connecting to a 12V marine battery. • It will contain a 5V regulator needed by the CPLD, Display, and Receiver blocks • It will contain a 9V regulator needed by the Transmitter and Receiver block • A transformer will drive the transducer • A transistor, supplied by 12V, will act as a “switch” for the transformer. • The purpose of this block is to supply all blocks with the voltage necessary to perform their functions. • Powers the transducer and helps to provide a means of portability. • A 4 amp max current will be supplied. • The On/Off switch for power will be located on the display.
Standard Requirements Max Operating Temp Range: 0C to 55COperating Voltage Range: 10.0V to 14.8VPower Source: D-Cell BatteriesMax Product Volume: 500 cm^3Max Mass: 2.5 kg Performance Requirements Power Modes: On (+12V), Off Min Current Requirements: 5V: 410 mA 9V: 160 mA 12V: 2 AMaximum Current Supply: 4ATransducer Supply Voltage: 150 Vpp @ 50 kHzReceiver Supply Voltage: 5V
Block Diagram BreakdownPower Supply Transmitter Input Transistor to Power transducer Marine Battery 5V Regulator To User Interface, CPLD, Transmitter/Receiver Switch +12V To Transmitter/Receiver Circuit D-Cell Battery Pack 9V Regulator
Block Preliminary SchematicPower Supply • +12V supply • +9V, +5V regulated • AC signal generated from transmitter pulses • Step-up transformer to drive transducer • Need to drive 150V bias @ transducer after transmitter pulses to “listen” for return signal.
Block Detailed Design Calculations & Component Selection • All components are to be thru-hole. This allows for easier prototyping. • Bypass capacitors are added to both sides of each regulator for decoupling. • The voltage regulators are of TO-220 package. They are cheap, heat sinkable (in case too much current), and easily mountable • 5V: 7V*.750A (max) = 5.25W Using a 20W regulator • 9V: 3V*.5A (max) =1.5W Using a 5W regulator • Safety Devices: Fuses, especially for the transducer which has a high current draw. • +12 V supply ~2A in operation, +9 V supply ~160mA • 4A fuse • +5 V supply <500mA from display, ~10mA from microprocessor, ~250mA to other board • 1A fuse • Transistor • 2A will flow across the transistor during operation. • The transformer will be supplied 5V, leaving 7V VCE • 2A*7V=21W • The transistor is rated up to 75W • Transformer • 5V input • Need 150V out to secondary
TransmitterBlock Description and Purpose • The purpose of this block is to provide the signal to drive the transducer • Takes DC voltage and turns into 50 kHz square wave • Square wave is transformed into a sine wave. The sine wave is amplified and then drives transducer
Performance Requirements • Transducer must be in a water-tight enclosure • Must receive between 4.5 and 18 Volts from the power supply • Transducer power supply must be able to generate 16 pulses at 50kHz, and shut off until the pulse is received back. • Amplifier must take approximately 6 V at 200mA, and convert it to the transducer bias voltage of 150V
Block Diagram Breakdown Slide 50 KHz Signal Generator Amplification Circuit From Power From CPLD: Control for how Long signal is generated 50 kHz Ultrasonic Transducer To CPLD
Theory of Operation • LM555 timer chip generates a 50 kHz square wave • Disable pin allows CPLD to control periods of signal generation • Second-order low-pass filter removes harmonics to create a more sinusoidal signal • Sine wave drives the base of a transistor to power the transducer
Equation Solutions • Ra arbitrarily chosen as 1 kohm • C = 1 nF • f = 50 kHz = 1.44/[(Ra + 2Rb)C] • Rb = 13.9 kohm • THIGH = (.693)(Ra + Rb)(C) = • 1.03257 * 10-5 • TLOW = (.693)(Rb)(C) = • 9.63 * 10-7
Preliminary Bill of Materials • National Semi-Conductor LM555 Timer Chip • RS ¼ Watt, 5% Tolerance Resistors • .01uF Capacitor • 1 nF Capacitor
Part Rationale • LM555: • Ability to create necessary frequency signal • Ability to be shut off from outside source • Stable operation between 4.5 and 18 Volts • Running temperature range (0-70 degrees C) • Small package type: DIP8 • Low-Cost : $1.69 individual cost
Part Rationale • RS 271-280 Micro-Size Potentiometer • Compact size • Availability • Easily tunable prototype • Low-cost: $1.49
Package Type Rationale • RS ¼ Watt, 5% Tolerance Resistors • Power ratings meet needs: Typically can handle between 200 and 250 Volts. They will not see more than 150 V.
Analog Block DFM - Passive Discrete Table • Worst-Case: Square Wave Generator • f = 1.44/[(Ra + 2Rb)C], • Ra=990-1010, Rb=13761-14039, C=9.9e-10 – 1.01e-9 • f = 49.0-51.0 kHz • Worst-Case: Low-Pass Filter • fb = 1/[6.283(R2C2)1/2 • R = 297-303, C = 9.9e-9 – 1.01e-8 • fb = 52.0 - 54.1 kHz
Receiver • Purpose • The receiver block will amplify an input signal from a transducer. This amplified signal will than be fed into a tone decoder which will swing low when the specified signal is detected. This low will then go into a voltage comparator to give the microprocessor a clean signal.
Receiver Block Standard Requirements The receiver block must be able to amplify a signal from +/-5 mV pk to 5 V pk for input into the tone decoder. The output must produce a 0 V dc level , 0-800mv and 2.5 to 5V for logic high, for input to the CPLD. Standard Temperature range 0-55 C Max current 150 mA Voltage rating 4.5 – 5.5 V
Receiver Block Performance Requirements -The amplifier block will amplify a signal from the transducer to a .2 – 4.5 V signal for input to the tone decoder - The logic low from the tone decoder must be less than 2.5 v, and have a fall time of less than 50ns. - The logic High must be greater than 2.5 volts and have a rise time less than 200 ns
Receiver Block Performance Requirements - The comparator block will be configured to account for a .25 V hysteresis - No potentiometers will be used in the circuit all resistor values will be calculated based on the 50 kHz signal