Restaurant Ordering System

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Restaurant Ordering System

• Group 15
• Dustin Selvey
• Joel Ingram
• April 28, 2006

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Introduction

• Our Restaurant Point Of Sales (POS) system
  provides a cost effective solution to managing
  orders, revenue and inventory.
• The software is complemented with our own cheap
  and ultra-long range pager system for automatic
  notification upon order completion.

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Features Software

• Web server application why?
• Cost effective
• Support for any number of workstations
• No setup needed for workstations only a web
  browser is required
• Statistics and current status can be easily
  viewed remotely
• Change service type to remote
• Open source languages and operating system for
  server eliminates any licensing costs

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Features Software

• Tracks food orders from the servers to the
  kitchen
• Tracks inventory and statistics
• Automatically updates revenue and cash flow
• Manager can access and view status of the
  restaurant remotely
• Very generic and modular

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Design - Software
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Testing - Software

• Test Hardware
• Old Pentium III
• Gentoo Linux
• 256 MB RAM
• Very acceptable speed results
• A commercial product would have much better
  performance

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Testing - Software
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Communication Link - Software

• Simple Linux binary to write characters to a
  serial port.
• Database buffer method
• Two main scripts
• Fill database
• Read database and transmit
• Both run as simple cron operations

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Communication Link - Software

• Database buffer method
• - Requires more CPU power
• - Constant database activity
• Modular
• Cost Effective
• Satisfies Goals

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Hardware Concepts The design of an ultra-long
range and low power pager system
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Features - Hardware

• Automatic server paging system increases
  efficiency by immediately and accurately alerting
  servers to an orders completion
• Up to 250 pagers are supported on a single
  transmitter
• Transmitter communicates with the server through
  a serial link

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Features Hardware

• Range coverage of a typical restaurant
• Battery lifetime of at least one week
• Small aesthetically pleasing design
• Programmable addresses allow for easy replacement

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Linx 418MHz (1/4 wave) 50 ohm antenna
ReceiverSchematic
Linx 418MHz Long Range RF Receiver
Microchip Pic16F688 With built-in EUSART
3v dc supply From 2x AAA batteries
65 mA dc vibrator
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3v dc supply from commercial adapter
Variable resistor to comply with FCC regulations
Linx 418 MHz (1/2 wave) 50 ohm antenna
Max232 chip converts RS232 to 3v signal
RS232 from Computer
Linx 418Mhz Long Range RF Transmitter
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Advanced Design Features

• To maximize range we use odd parity and start
  characters for each command
• To maximize battery life we implemented two
  separate sleep commands
• Sleep Pic
• Sleep Receiver
• To make the pagers easily replaceable we store
  addresses in flash memory for convenient changes.

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Testing - Hardware

• Input voltage ranges were tested
• Battery life was theoretically calculated and
  then proven
• Range was tested in various environments

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Results of Testing

• Using a half wave antenna will increase the
  transmission strength by 10db (or 10 times) vs.
  an unmatched antenna
• Using a grounded plane at least 3 inches in
  diameter will increase the transmission strength
  by an additional 3db (or 2 times).

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Results of Testing

• The input voltage must be between 2.9 and 3.6
  volts with no more than 20mV of noise
• Must be placed at least 6 inches clear of sources
  of interference (computer, cordless phone,
  kitchen appliances, etc.)

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Results of Testing

• In an open environment the maximum operating
  range is 1000 feet.
• With the transmitter in the senior design lab,
  reception was strong throughout the south side of
  the building and intermittent just outside the
  brick walls.

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Results of Testing

• Theoretical Battery Lifetime
• 22 days from Alkaline batteries
• 28 days from lithium batteries
• 39 days from lithium batteries when the pager is
  turned off at night
• Actual Battery Lifetime
• Lithium batteries installed on prototype March
  20 are still powering the receiver at full
  voltage as of April 26

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Results of Testing

• Limitations of Receiver
• Nickel Metal Hydride batteries WILL NOT WORK!
• Alkaline batteries are o.k. but NOT recommended
• Speed Limitations
• Maximum transmission 55.6 kbits/second
• Minimum transmission 300 bits/second
• Lower transmission speeds reduce both power and
  range

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Antenna Considerations
½ Wave Antenna
¼ Wave Antenna
Grounded Plane Antenna
Best RF Reception
Great reception with perpendicular grounding
plane decent otherwise
Good reception with perpendicular grounding
plane bad otherwise
Large, 7
Small, 1.6
Very small, internal
Chosen for transmitter
Chosen for receiver with 1x1 grounding plane
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Results of Testing

• Important Antenna Lessons Learned
• Many structures and traces used within our PCB
  are antennas
• As much as possible we would like to eliminate
  the use of these structures and traces
• If we cannot eliminate them, we must minimize
  their radiation efficiency
• Always look at your design from an antenna point
  of view
• Remember your electronic systems are antennas,
  and what you dont know about them could hurt you!

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Looking Towards the Future

• Advanced statistics and inventory tracking
• Needs to be fully tested in an actual restaurant
• Built-in rechargeable units to each pager
• Needs to be verified compliant to FCC Part 15
  Class B emission requirements before going
  commercial

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THE END

• We want to thank the following people for their
  help throughout our project
• Abraham Rozental
• Alex Spector
• Andrew Bean
• Linx Technology (design help)
• Microchip (free samples)