P A MPersonal Ambience Monitor

Timothy Stotts,Shawn Pfister &Bhushan Mehendale

2

Agenda

• System Overview• Mobile-Unit Details

• Display System• Sensor & Data-Collection System• Remote Communication System

• Base-Station Details• Remote Communication System

• Testing• Applications• Q & As

3

System Overview• Two parts—Mobile-Unit & Base Station

• Mobile-Unit (MU):• Display critical parameters such as external temperature, heart-rate,

GPS data, remote messages on head-mounted display• Two-way communication with a Base-Station• User can see surroundings & view this data at the same time.

• Base-Station:• Receives real-time information from MU• Can send messages to MU• Uses simple to use GUI application to achieve this• Runs on any PC

4

High-Level System Diagram

Mobile Unit

Base Station

Heart-rate sensor

External Temperature

Sensor

GPS

5

Mobile-Unit Details• Processing

• Contains one PIC18F4520 (< $10/piece)

• Display Driver• XBOB by Decadenet Engineering

• Communication Hardware• AeroCable Bluetooth Dongle

• Level Shifters• Famous MAX232 level shifter chip

• Power Supply• MU works on a 9V battery (for XBOB, built-in voltage regulation from 8V to 15V)• All others work on 5V supply—regulated by the LM7805/TO-92 voltage regulator

chip

6

Mobile Unit System Diagram

PICGPS

Video

1Wire

RF

RS232 Transmitting and receiving lines

7

PAM’s Display System

• Needed way to display on a screen in a “near-to-eye” fashion, without obstructing users view.

• Two options found:• Take simple LCD, and use optics to make image “appear at

infinity”• Too bulky• Thinner lenses are very

expensive

• Use ready-made solution• Very high-resolution QVGA displays available• Optics are already taken care of• Is part of a very good mobile-computing system

ff

8

PAM’s display system

• Two such ready-made solutions available:• MicroOptical MV-1

• $475 (B/W)

• Eyetop Classic• $230 (Color)

9

PAM’s display system• Both varieties accept NTSC signals as input

• Needed a way to generate “NTSC” text to put in as video

• Variety of chips available to do the job• STV5730• Mitsubishi 35060

• Can be only bought in bulk—500 or more, each for $25. Individuals sell for $50 or more

• XBOB by Decadenet has the Mitsubishi 35060 on their XBOB, and it does all the required functionality through RS-232

• We spent little more money, and got the board.

10

PAM’s Display System—XBOB

•Can Overlay NTSC text on incoming video!

•Ideal size for mobile unit

11

Sample Output

• We generated a sample output from the system, as seen by the user:

12

1-Wire Network

• Key Attributes• Low Power

• Only one wire for both power and signal.

• Extendibility • Adding new sensors or devises can be incorporated with

little to no effort.• The data acquisition algorithm becomes homogenous

because each devise uses the same communication protocol.

• Easy interface • Can be done with minimal code segments (saves

memory)

13

Sensors• ADC - Dallas Semiconductor 1-Wire

Quad A/D Converter DS2450 • Used to interface analog sensors into

the one wire network. Up to 4 analog inputs.

• Heart Rate Sensor - CI6543B from PASCO.

• The sensor comes with an amplifier box that conditions the heart rate signal by reducing noise and amplifying the signal. The output voltage range of the amplifier box is 0V to 5V making it safe to connect directly to a port on the PIC microcontroller or a 1-wire ADC. The amplifier box also eliminates the need for external signal conditioning circuitry.

• Temperature Sensor- Dallas

Semiconductor 1- Wire DS1820 • Digital Output 2’s Compliment

Important temperature sensor specifications.

14

1-Wire Network Testing

• Write the one wire drive.

• Examine the 1-Wire driver out with a scope to verify that the signal timing requirement are correct.

• Connect one 1-wire device and establish communication.

• Verify that the data being received is correct.• Correct temperature reading hot/cold conditions. • Apply dummy values to ADC and ensure the data

being read from the devise is correct.

15

GPS Axiom NMEA GPS

• Attractive Features:• RS232 Interface• Low Power consumption 180ma cont..• Small physical size• Accuracy

• 1-5 meters for position

• Obtainable data parameters• Position• Elevation• Speed

16

RF Components• Base Station BlueTooth Dongle

• Class 1, 100m range• USB HCI interface – Macintosh, Linux, Windows• Dependent upon OS BT stack/subsystem• Connects with Mobile Unit via RFCOMM

• Mobile Unit BlueTooth Transceiver• Class 2, 10m range• RS232/DB9 interface (i.e., 9-pin PC serial)• 10V DB9 will be adapted to UART 5V with MAX232

component and custom wiring• Self-contained BT stack/subsystem

17

Microcontroller PIC18F4520Design Decisions

• Size and weight: the PIC microcontrollers are extremely small and light in weight. This is desirable because the system is to be mobile.

• Cost: Each PIC is under $10• Speed:The PIC 18F4520 can be clocked up to 40 MHz. The system requires

real-time calculation. Therefore, the microcontroller must be fast enough.• Scalability: Although it is believed that the on board memory (256 bytes

EEPORM, 1536 bytes RAM, 16K flash) will be sufficient, The PIC is capable of addressing up to 2Mbytes in the event more memory is needed or additional features are added.

• Wide operating voltage range: The system will be battery powered. Therefore, a constant power supply can not be guaranteed. Consequently a large operating voltage range is desired.

• Programmable interrupts: Although the precise application of this option is not yet know, the capability is convenient to have.

• RS-232 Support• I/O pin count: Since, a variety of devices will be connected to the controller, an

adequate pin count in need (5 I/O ports available). • Sensor• GPS module• Network card.• Future expansion

18

Data Acquisition Flow

Read 1 Wire Devices

Read GPS Devices

Update and send data to display

Send/Receive Data via RF

19

Base-Station GUI• The base station window will perform the following operations:

• select mobile unit to track• send messages to mobile unit• monitor statistics of mobile unit at specific refresh rate

• Requirements:• Cross-platform design with Python and wxWindows• Operates on Mac OS X, Linux (and maybe Windows)

external temp: +96 ºFheartbeat: 78 bpsgps latitude: +47º 3'gps longitude: +31º 1'gps altitude: +1150'gps velocity: 2'/s N send msg

head toward the largebrick structure

stop! go back!

Last message

New message

effective refresh: 1.7 Hzconfigured refresh: 3.0 Hz

refresh now

change rate

mobile ID: alpha24

select mobile

20

General Testing Methodology. • The modularity of this project lends itself to

incremental testing procedures.• Each of the following piece will be developed and

tested individually before integrating them into the project. • 1-wire driver

• Each sensor will be tested individually before integration into the entire network

• RS232 driver – general communication and setup(baud rate)• Specific Display routines• Specific GPS command routines• Specific RF module routines

• Base Station GUI • Base Station RS232 driver

21

Cost Estimate

22

Q & A

?