Transcript Wireless Null Modem

Wireless Null Modem
Infrared Palm Pilot Communication
Device
Team Members
• Team Leader:
– Peter Trenkle
• Group Members:
– Huiyang Sim
– Shaun McFarland
– Stephen Porter
Abstract
• Design an infrared console that eliminates
the need for a DB-9 serial cable to transmit
data to a PDA
• Develop software that will allow users to
establish a data link between the console
and the Palm Pilot
Motivation
• Palm Pilots are cheaper and easier to carry
than laptops with null modem cables
• Infrared technology has allowed for lowspeed data links in handheld computing
devices
• Ability to supply a cheap, convenient
alternative to a laptop interfacing to an
ASCII display menu
Why Use Infrared Technology?
• Infrared technology is perfect to replace the
cable required by the RS-232 interface
• Low level infrared data links can transmit
data at up to 115.2 kbps
• Infrared data links are feasible at distances
of up to three meters
• Infrared standard will allow for thousands
of products to interface to our design
Design Constraints
• Design an Infrared Console to Establish a
Data Link and Tx/Rx RS-232 data through
the Infrared Data Link
• Transmit and Receive Infrared Data at a
Rate of 19.2kbps with a Bit Error Rate of
10E-9
• Develop Software for PALM to Detect a
Data Link and Display ASCII Menus
Design Constraints
• Create a 1 meter Infrared Data Link
• Physical Packaging
– The size will be no larger than 2” x 1.5” x 2.25”
(H x W x D)
– Components have small footprints
• Cost
– The cost of parts and packaging will be < $30
Low Power Requirement
• Typical use of our product will be defined as 15
minute intervals, with long delays between use
• One 9 Volt battery will be used to supply power to
our project
• Due to the excessive power needed by the IR
transceiver, several aspects of the transmitted data
are observed
– screen refresh rates
– amount of characters on each screen
• By knowing the current rating of the 9V battery
(120mah @ 9V) we can define a simple formula
showing battery life depending on current drawn
Low Power (cont.)
• Battery life in hours = 120mAh / X (# mA drawn)
• The PIC, External UART, and Line Driver pull
approximately 2mA at the given clock speed
(4Mhz)
• The IR Transceiver draws several times more
power (~100mA) depending on the length of time
it transmits
• This will be limited by controlling the duty cycle
and transmission rate of the IR Transceiver
• Maximum Power will be determined when final
prototype is developed
Development Plan
Hardware Design
Determination of Components
Finished Schematic
PIC C Firmware Dev.
Palm OS Dev.
Basic Serial I/O into the PIC
“Hello World” On Palm
Packetize Data
Serial Com Via Palm
Implement IrComm Standard
Infrared Com Via Palm
Final Testing and System Integration
Hardware Design
• Hardware was chosen by considering the
Design Constraints
– Power Consumption
– Performance at low clock speeds, further
decrease power consumption
– IrDA Timing Compatibility
– Large amounts of buffer space for creating
packets of data
Diagram of Hardware
From RS-232
@ 19.2 kbps
RS-232
Line
Driver
On-Board
UART PIC 16F877
On-Board
SPI Port
Maxim 3100
Controls IrDA
Timing for the PIC
PIC Controls
capture of serial data
from SPI Port and
UART. This data is
then decoded
from/encoded into
IrDA compatible
data
To PALM
MAX3100
Infrared
Transceiver
From PALM
Component Costs
Compone nts
Price pe r unit ($)
PIC16F877
5.95
MAXIM 3100 UART
4.43
MAX 232A
2.45
INFINEON IRMS 6118
1.50
Capacitor (0.1F)
0.06
Resistor (22 )
0.02
Resistor (47 )
0.05
Packaging cost
10.00
Total cost
24.46
Embedded Software Design
– Use the PC’s serial port to transmit serial data to verify
the UART
– Create Modular I/O routines for SPI module on PIC
– Interface the PIC to the Max3100 UART to control
IrDA timing
– Transmit and Receive Data between the RS-232
Interface and the Infrared Interface
– Port existing IrComm Assembly Code into C Code
– Build the IrDA protocol layer by layer, testing each as
it is completed
– Test the final software program using IrPing()
Palm OS
Development
• Learn the basics of the CodeWarrior language for
Palm OS
– Work on “Hello World” program
– Start with Initial Serial Port programs
• Create a program that allows for bi-directional
serial communication
– Send Data Bi-directionally from PC to Palm Pilot
– Add User Input Functionality
• Move serial port program to interface to the
Palm’s onboard infrared port
Test Specification
• IrPing() – IrDA protocol stack analyzer for the Palm
– Will test the IR data sent by the Console and Palm
– Will verify the IrDA protocol layers implemented in
Firmware
• Oscilloscope
– Will check the clocking of the SPI Port of the PIC and
the Data Rate of the RS-232 Interface
– Will allow complete verification of hardware design
• Performance Testing
– Create a real world simulation environment
– Perform Peak Performance Testing and Typical Use
Testing
• PC’s IR port will act as Bit Error Rate Tester
Test Specification
Design
Constraint
IrPING( )
Performance Testing
Encode/Decode
IrDA @ 19.2kbps
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Implement
IrComm
Standard
Create 1 meter
Data Link
Hardware
Palm Pilot
Terminal
Program
PC IR Port for Bit
Error Rate Test
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Accuracy of
Infrared Data
Power
Oscilloscope
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End of Semester Delivery
• Demonstrate our bi-directional Palm Pilot terminal
program
• Any IR Links unable to be implemented will be
simulated by a null modem cable
• Transmit/Receive IR Data with limited IrDA
functionality
• Complete IrDA functionality will be completed by
February of 2002
• PC Board will be laid out and ready for order
Summary
• Design and Implement a small, low-power
RS-232 IR console
• Create a Palm Pilot Program that displays
ASCII data on screen
• Create a convenient, low-cost alternative to
laptop-to-serial-cable communications
Future Applications
• Remote control of Serial Devices
• Make software compatible with different
PDAs for greater market penetration
• TCP/IP functionality to allow for low speed
internet connections on the PDA
Acknowledgements
• We would like to thank Dr. Robert Reese,
our advisor, for all his valuable input
• We would also like to acknowledge Dr.
Joseph Picone for his support