Restaurant Ordering System

Group 15Dustin SelveyJoel IngramApril 28, 2006

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.

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

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

Design - Software

Server/Database• Maintain order database• Track inventory

Waitress Stations (2-3)•Input orders•Change orders•View order status

Kitchen• View orders• Update order status

Office• View all other nodes• View statistics• View inventory

Cashiers Station• Complete orders / Issue receipts

Electronic Pager• Automatically pages waitress upon completion of order

Testing - Software

Test Hardware– Old Pentium III– Gentoo Linux– 256 MB RAM

Very acceptable speed results A commercial product would have much

better performance

Testing - Software

Select Tests(seconds per command)

Insert Tests(seconds per command)

Single Connection

0.0172

0.0395

0.0489

0.00212

0.00248

0.00301

Multiple Connections(three connections)

0.0612

0.1285

0.1456

0.00681

0.00712

0.00746

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

Communication Link - Software

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

Hardware ConceptsThe design of an ultra-long range and low power pager system

Features - Hardware

Automatic server paging system increases efficiency by immediately and accurately alerting servers to an order’s completion

Up to 250 pagers are supported on a single transmitter

Transmitter communicates with the server through a serial link

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

Linx 418MHz

Long Range

RF Receiver

Microchip

Pic16F688

With built-in EUSART

Linx 418MHz (1/4 wave)

50 ohm antenna

3v dc supply

From 2x AAA batteries

65 mA dc vibrator

ReceiverSchematic

RS232 from Computer

Max232 chip converts RS232 to 3v signal

Linx 418Mhz Long Range RF Transmitter

Linx 418 MHz (1/2 wave) 50 ohm antenna

3v dc supply from commercial adapter

Variable resistor to comply with FCC regulations

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.

Testing - Hardware

Input voltage ranges were tested Battery life was theoretically calculated and

then proven Range was tested in various environments

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).

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….)

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.

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

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

Antenna Considerations

½ Wave Antenna ¼ Wave Antenna Grounded Plane Antenna

Large, 7” Small, 1.6” Very small, internal

Best RF Reception Great reception with perpendicular

grounding plane; decent otherwise

Good reception with perpendicular

grounding plane; bad otherwise

Chosen for transmitter

Chosen for receiver with 1”x1”

grounding plane

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 don’t know about them could hurt you!

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

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)