SmartBadge version 1

"A SmartBadge is a wearable computer with an infrared data link and a collection of environmental sensors. It is designed to be work like a corporate identity badge. The SmartBadge communicates with fixed Badge Tranceivers using a subset of the IrDA IrLAP protocol stack. Every 2.3 seconds the SmartBadge broadcasts a message giving its identity and details of the state of its sensors. A Badge Treanceiver picks up the message and forwards it to a Badge Server which de-encapsulates the Badge data from the IrLAP frame and forwards the information to a Location Server that tracks the location and state of Badges, Treanceivers and people." (From the lab notes for the course.)

The first version of the SmartBadge has been used in classes at KTH (Mobile Personal Communications module of the Telecommunications "finger" course during Spring 1997) and University of Wollongong (during Summer 1997). This version was mainly designed during winter 1997 by Dr. H. W. Peter Beadle, then of the The Institute for Telecommunications Research, Electrical and Computer Engineering, University of Wollongong, Australia in cooperation with M. T. Smith of HP Labs and G. Q. Maguire Jr. of KTH.

This version used a 2 layer circuit board made by Mark T. Smith of HP Labs using a PCB milling machine.

Front and Back Badge views

The basic system consists of an EEPROM programmable 20MHz 8 bit PIC microcontroller with A/D Converter (PIC16C74-JW) and a number of sensors.

Schematics

• not on-line

Parts and reason for their selection

• • EEPROM programmable 20MHz 8 bit PIC microcontroller with A/D Converter (PIC16C74-JW)
  • lots of general purpose and I/O interfaces, an on-board A/D converter with 8 multiplexed inputs, and UART
• • low power, with power saving SLEEP mode
  • DC-20 MHz operation (fully static design) - we used a 10 MHz crystal osc. for the processor and a 3.6864 MHz for the UART
  • 4K x 14 EEPROM - incircuit programmable
  • 192 bytes of memory
  • Also available as a One Time Programmable 10 MHz part (PIC 16C740-10)
• Audio/noise
  • Piezoelectric transducer - for noise output (77dB@30cm 4kHz, can handle 10V p-p (Farnell part 561-071) - replaced on many by Radio Shack 273-074 speaker
  • microphone (60J42) for audio input
• IRDA IR transceiver module
  • TEMIC TOIM3000 interface module and TFDS3000 transceiver
• Tilt sensors (tilt switches)
  • non-mercury Asemtech CW1300-1 (Farnell part #540-614)
  • using two pairs (mounted at 90 degrees to each other) of 2 sensors
  • inexpensive (~11 SEK/each) means of generating orientation data
• Temperature sensor - Thermistor 330k Ohm
  • Philips 330k Ohm @25 degrees C, NTC 5%
  • Farnell part #265-720
• Humidity sensor (C5-M3)
  • "Miniature sensor using a humidity sensitive material screened onto a ceramic substrate. The resistance of the the device varies expontentially with relative humidity. It as rapid esponse and good reproducability." Operating humidity: 90% RH (max)
    Rated voltage, power (AC) 1 V rms, 0.2mW
    Driving frequency (recommended) 500 Hz to 2kHz
    Storage conditions (recommended) 10 degrees to 40 degree, 0-60 percent RH
    Operating temperature range 0 degrees to 60 degrees
    Standard humidity resistance 31K Ohm (at 25 degreees C, 60 perecent RH)
    Humidity detecting accuracy +-5 percent (25 degreees C, 60 percent RH)
    Temperatue dependence 0.5% RH/degree C
  • Farnell part#540-985
• FUJI & CO.(Piezo Science) Light Dependant Resistor (MPY54C569)
  • front mounted Light Dependent Resistor
  • CdS Photoconductive Cells, MPY Series
  • Peak-sensitivity wavelength: 550 nm
  • Light Resistance 10Lux 20-100k Ohm
  • Dark Resistance min 20M Ohm
  • Farnell part#179-611
• 3V Litium button battery - mounted in a coin battery carrier

Software

SmartBadge Programs

SmartBadge (Version 1.1, C for PIC 16C74A-JW @ 20MHz) (Version 1.1, C for PIC 16C74A-JW @ 19.660800MHz)

• All Badge communication is at 9600 baud, 8 data bits, one start bit, one stop bit, no parity.
• On power-up the badge beeps and waits for its ID to be programmed across the IrDA link. When it starts up it sends a version number string followed by a 'P' it then attempts to read a character from the IrDA link. If the character is an 'i' it then tries to read four additional characters that are the badge address. If anything other than 'i' is read then the Badge sends another 'P' and waits for another 'i'. After the initial 'i' you have 2.3 seconds to enter each succeeding character. If the Badge is not programmed after 20 seconds it assigns a default badge ID of 0xFFFF and starts operation. The Programmer program in the PC Support Programs effectively programs the badge to a definable ID.
• Once the Badge ID is programmed the SmartBadge program checks the tranceiver jumper on the Badge board and decides if it is going to operate in Badge mode or Tranceiver mode.

Badge Mode

Once operational the Badge polls its sensors, sends a Badge frame and then waits for 1 second for incoming Badge command frames. It then sleeps for 2.3 seconds and repeats the process. If an incoming Badge command frame is recognised the command is executed and the badge resets its timeout and waits for additional commands for 1 second. Back-to-back commands are thus possible without the Badge going to sleep.

Tranceiver Mode

• Turns a Badge with Daughter Card into a null-modem converting between IrDA physical and RS232 physical one character at a time.

All the badge code was developed using PICSTART-16C - a PIC development environment.

Badge Server

Badge Server takes IrDA IrLAP frames delivered from a Badge Tranceiver across the Internet. Parses the content and then forwared the data to the WWW based Location Server as a HTML message. The program is also capable of forwarding IrLAP frames data back to the Badge Tranceiver to be passed on to a Badge.

Badge Tranceiver

Reads badge data from the serial port of a PC (Presumably from a Badge running the tranceiver program) and sends it to a badge Server runing somwhere in the Internet. The program can also receives IrLAP format frames from the Internet and send them to the Badge through the serial port.

Locator

Allows a person to register with the Location Server on the Interner when they log on to a computer.

Programmer

Allows the Badge ID to be programmed on Badge power-up. Programming sequence is the character i followed by 4 bytes giving the Badge ID. You can also type this in from an IrDA equiped notebook (e.g. OmniBook). Repeat until the badge beeps at you or 20 seconds expire at which time the baged starts up with a broadcast address of 0xffff.

Fake Badge

Allows you to specify the Badge address, Badge Tranceiver address and send an update message to the Location Server as if the Badge had been seen by the Tranceiver.

Related Work

SmartBadge

• Location Aware Mobile Computing Master Page - was at http://www.elec.uow.edu.au/people/staff/beadle/badge/location_aware.html
• H.W.P. Beadle, G.Q. Maguire Jr., M.T. Smith, "Environment Aware Computing and Communication Systems", submitted to: Proc. International Symposium on Wearable Computers, Cambridge, Massachusetts, October 1997, Submitted -- but was rejected!
• H.W.P. Beadle, G.Q. Maguire Jr., M.T. Smith, "Smart Badge: It beeps, It flashes, It knows when you are hot and sweaty", submitted to: Proc. International Symposium on Wearable Computers, Cambridge, Massachusetts, October 1997, Submitted -- but was rejected!
• H.W.P. Beadle, G.Q. Maguire Jr., and M.T. Smith, Presentation Slides, for seminars to Institut für Technische Informatik und Kommunikationsnetze and Physical Electronics Laboratory, ETH Zurich April 1997.
• H.W.P. Beadle, B. Harper, G. Q. Maguire Jr., and J. Judge, "Location Aware Mobile Computing", Proc. IEEE/IEE International Conference on Telecommunications, (ICT"97), Melbourne, April 1997.
• H.W.P. Beadle and R. Gonzalez, "A Video Coding Based Mobile Multimedia Terminal", Proc. Picture Coding Symposium, Melbourne, 1996, pp. 509-514.