Bus Tracking System characterazation presentation

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High Speed Digital Systems Lab
Bus Tracking SystemFinal Part B presentation
Presented by Gal gavish and Yuval
Peled Supervisor Hen Broodney
Spring 2004
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(No Transcript)
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Projects Goals

• Create a system that tracks a bus and gathers the
  arrival times to each station along its route.
• The system includes only one module the bus.
• The bus identifies a stations position using GPS
  and prints it to LCD

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General System Requirements

• Independent of human intervention.
• Gathers the time of arrival only to stations that
  belong to the buss route.
• Print stations ID and allowed speed in the area.
• Low power consumption.

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GPS Global Positioning System

• Position is determined by the distance from 3 or
  4 satellites.
• The position calculation is done insideThe
  receiver and is transmitted to themicro-processor
  .
• A new position calculation is done every second.
• The GPS accuracy is up to a few meters. (10 15)

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GPS Time to first fix

• Cold start less than 2 minutes. Search
  satellites, collect ephemeris and almanac data,
  compute position fix.
• Warm start less than 45 secondsNo satellite
  connection for more than 1 hour, but
• back up voltage keeps almanac and ephemerisHot
  start less than 20 secondsNo satellite
  connection for less than 1 hour, but
• back up voltage keeps almanac and ephemeris

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GPS Interface HW
Development board
5 Volt

To RS232 Port
GPS Receiver
RS232 connector
Maxim 232A
Antenna
RS232
TTL/CMOS Level
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Block diagram for the bus module
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GPS Message packets

• Packets structure
• ltDLEgt is the byte 0x10
• ltETXgt is the byte 0x03ltDLEgt ltIDgt ltdata string
  bytesgt ltDLEgt ltETXgt
• Every ltDLEgt byte in the data string is preceded
  by another ltDLEgt byte.

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GPS Message parsing
DLE
Status DLE 1
DLE
Status Empty
Status Full
ETX
DLE
DATA
ETX
DLE
Status DATA
Status DLE 2
DATA
DLE
ltDLEgt ltIDgt ltdata string bytesgt ltDLEgt ltETXgt
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GPS Packets implemented

• Time report Get the time of week from the GPS
• GPS status Print to LCD the current satellite
  communication status. How many satellites are
  visible, when it does position fixes, are the DOP
  too high, etc
• Single precision LLA Get the current position
  fix. It contains 3 float numbers representing the
  latitude, longitude and altitude calculated in
  the GPS module.
• Single precision Velocity Get the current
  velocity and movement direction of the bus. It
  contains 3 float numbers representing the
  velocity north, east and up.
• Double precision LLA 3 double numbers
  representing the latitude, longitude and
  altitude.

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Software design

• We have 1 main module
• The bus module.
• And 4 utility modules
• UART module
• GPS module
• I2C module
• LCD module

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Software Architecture
Bus
UART module
Initialization
Receive position Print result
I2C module
LCD module
EEPROM Search and write
GPS module
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Utility modules

• I2C module
• Write to and read from a shift register inside
  the PIC18F.
• No interrupts needed.
• GPS module
• Implemented TSIP (Trimble Standard Interface
  Protocol).
• UART module
• Used to connect between the GPS and the
  microprocessor software.

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Bus moduleprogram flow
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Bus module - interrupts
GPS
Initialize Wait
Connected
UART High priority interrupt
EEPROM Phase
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Timing

• EEPROM timing
• Write/read 8 bytes from serial 8 bit bus using
  the shift register.
• 5 msec each read/write action.
• Search a station in table takes 50-100 msec.
  (before displaying the speed)
• GPS timing
• Sends position message every one second.
• Sends health message every 5 seconds

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Power consumption

• PIC18F4521.6 mA
• GPS receiver50 mA
• GPS Antenna150 mA
• EEPROM3.2 mA
• Max 232A10 mA
• TOTAL 215 mA

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EEPROM - Memory
4 bytes Longitude 4 bytes Latitude
2 bytes Time of week 6 bytes Stations ID
1 byte Speed and number of lines 3 bytes Line number

• List of all stations
• Up to 3000 stations, Average of 8 lines in each
  and 1 speed mark 3000 x (4 4 6 8 x 3 1)
  115KB
• List of stations in route
• Up to 400 stations and arrival times
• 400 x (8 2) 4KB

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Goals accomplished

• Find and purchase a GPS receiver and antenna.

• Learning TSIP and implementing it on the
  PIC18F452

• Install new GPS hardware on the development
  board.

• Integration of GPS, UART, LCD and I2C modules on
  the PIC.

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Conclusions

1. The GPS module of part B can be combined with the
   Bluetooth module of part A- it will enable a
   much faster connection establishment between the
   bluetooth devices.- it will enable passing
   information between buses and stations such as
   time of next arrival, current position or even
   commercials.
2. The GPS module of part B can be combined with a
   cellular device- it can enable all position
   calculations and memory accesses to be done in a
   remote server thus minimizing the embedded
   systems complexity.- anyone with a cellular
   device can receive real time information about
   buses positions and expected time of arrival.

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High Speed Digital Systems Lab
Bus Tracking System Final part B presentation
Presented by Gal Gavish and Yuval
Peled Supervisor Hen Broodney
Spring 2004
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Hardware

• Microchip PIC18F452 a 40-pin chip.
• Trimble GPS Lassen SKII and antenna
• Serial EEPROM (24LC256) by Microchip - 256K x
  8bit.
• Clock generator 10MHz.
• LCD
• Battery 9V.

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Specifications Cont.
Microchip PIC18F452
DC 10 MHz Operating Frequency
32KBytes Internal Program Memory
1536 Bytes Data Memory
256 Bytes Data EEPROM Memory
18 Interrupt Sources
5 I/O Ports
4 Timers
Addressable USART, MSSP MSSP, Serial Communications
Yes Parallel Communications (PSP)
8 input channels 10-bit Analog-to-Digital Converter
Yes Programmable Low Voltage Detect
Yes Programmable Brown-out Reset
75 Instructions Instruction Set
40-pin DIP Package
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Specifications Cont.
Trimble Lassen II K GPS
12.504 MHz Operating Frequency
25 meters CEP Accuracy Position
0.1 m/s Accuracy - velocity
2 meters CEP DGPS accuracy position
0.005 m/s DGPS accuracy velocity
5 V DC 95 ma Power
0.47 ma Typical
3.2 V DC 2 micro amp RAM backup
2 TTL level, bi-directional, serial I/O ports Interface
TSIP TAIP NMEA Protocols available
-1000 m to 18,000 m Dynamics Altitude
515 m/sec maximum Dynamics Velocity
4g (39.2 m/sec²) Dynamics Acceleration
20 m/sec³ Dynamics Jerk
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Specifications Cont.
Microchip 24LC256 EEPROM
400 KHz Max. Operating Frequency
256K x 8 bits. Data Memory
2.5-5.5 V Vcc range
3 mA at 5.5V Max. write current
0.4 mA at 5.5V Max. read current
100 nA at 5.5V Typical standby current
2-wire serial interface bus, I2C compatible I/O
yes Schmitt Trigger inputs for noise suppression
64 Byte Page write mode
5 ms Max. write cycle time
1 million write/read cycles Endurance
gt 4000V Electrostatic discharge protection
gt 200 years Data retention
-40C to 85C Temperature range
8-pin DIP Package
yes Hardware write-protect for entire array
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EEPROM life expectancy

• Serial EEPROMs are typically rated to endure 1
  million write operations per byte.
• Every time the bus enters the central-station it
  clears the entire EEPROM memory.
• Assume the bus returns to the central-station 20
  times a day, 5 days a week.
• Life_expectancy 106 / (20x5x52) 192 years
• Before BER increases dramatically.

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Software tools

• Well be using the C18 C compiler from the MPLab
  IDE (Integrated Development Environment) to write
  our C code for the programs running on the PIC.
• Well be using the MPLab ICD 2 (In Circuit
  Debugger) to program the PIC.

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Debugging tools

• To debug the application programmed on the PIC
  well use the in-circuit debugger (ICD) supplied
  with the PICDEM 2 Plus development board.
• Since debugging with the ICD is slow, well also
  be using the LCD and the LEDs on the development
  board for faster and easier debugging.

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High Speed Digital Systems Lab
Bus Tracking SystemFinal Part B presentation
Presented by Gal Gavish and Yuval
Peled Supervisor Hen Broodney
Spring 2004