Meter Maid Alert

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Meter Maid Alert

• Project 7
• Miguel Alvarado
• Filiberto Haro
• Miguel Haro

ECE 345 Senior Design Fall 2000
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Introduction

• Goals
• Sense the Automobile
• Transmit meter id number
• Display meter location
• Benefits
• Increase revenue for the City
• More Efficient ticketing process

ECE 345 Senior Design Fall 2000
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Our Project
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Original Design
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Sensing

• Ultrasonic Sensors
• EDP Sensor
• Outputs 0-5 VDC
• Jameco Sensor
• Outputs 0-1 VAC
• Need AC to be DC

ECE 345 Senior Design Fall 2000
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AC/DC Amplification Circuit
ECE 345 Senior Design Fall 2000
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AC/DC Conversion
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ECE 345 Senior Design Fall 2000
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Amplification

• Output Voltages always a One
• Nothing sensed V 1.8 V
• Car sensed V 2.3 V
• Use HC12 A/D Converter

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Timing Diagram

• Make sure the car is parked
• Using digital counter
• Clock Frequency at 0.1 Hz
• Send Meter id number only once
• Using JK flip flops
• Notify meter maid when car leaves

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Final Design
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Transmission Block Diagram
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Transmission

• Transmit signal sent
• High for one second
• Complete meter ID must be sent
• Handled by Shift Registers

1 s
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Shift Registers

• Running at clock pulse of 1 kHz
• Two modes
• Parallel load 16 bit meter ID
• Serially shift out meter ID
• Transmit signal determines operating mode
• Capability for 1,000 bit transmission

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Meter ID

• 16-bit functionality
• Blocks W-Y Range 09
• Block Z Range 0-3

Stationary Transmit


LSB  
Bit Bit
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Meter ID (cont.)

• Decision based on LED display
• Can only display 0-9 in decimal
• Meter ID range
• Limited to 0-3999 in design
• Expandable to any practical number

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Transmitter / Receiver

• Linx LC Series of RF modules
• TXM418LC and RXM418LC
• Capabilities
• 418 MHz Transmission
• 0-5000 bits/second
• Range of 300 ft

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Our Design

• Shift register running at 1KHz
• Transmit _at_ 1,000 bits/second
• Helical antenna utilized
• Best overall performance
• More immune to interference than whip
• Range of 200 ft

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Time Delays in Transmission

• Short-range Transmission
• Internal chip delays found to be 50 µs
• Long-range Transmission
• 1 µs delay per 300 meters

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HC12 Microcontroller

• Utilized for hardware/software interaction
• Interpreting meter ID number
• A/D Conversion

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HC12 Software Flow Diagram
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Terminal Output
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Graphical User Interface

• Written in Visual Basic
• Functionality
• Allows user to enter a new meter address
• Assigns address a meter identification number
• Adds meter to the database
• Allows user to enter a meter identification
  number and retrieve the location

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GUI Display
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Challenges

• Obtaining consistent output voltages from sensor
• A/D conversion
• Transmission timing
• HC12 limited to 1kB of RAM
• Flash EEPROM offers additional memory

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Possible Future Enhancements

• Improve Tx/Rx range
• More software dependence
• Keep track of money fed to meter
• Service measurements

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Conclusion

• Project is feasible
• Further detailed testing necessary
• Additional capabilities would add to
  marketability

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Questions ???
ECE 345 Senior Design Fall 2000