11/1/11 notes (These are my "raw" notes from class... I will be back to edit these soon!)

Wireless communication, basic rundown RFID and NFC stuff next week


  • layered protocol when deal with radio
  • XBEE- cheap and reliable
  • Bluetooth receivers - relatively expensive
  • Zigduino - single chip solution to RF and microcontroller, can do a zigbee protocol
  • Zigbee stack is fairly complex
  • Nordic - RF 2401 series (sparkfun), less expensive, tougher interface

Synchronous or asynchronous serial interfacing

clock pin - synchronous

Issue always is: no wire, opportunity for interference

Terms: 2.4 ghz space - the frequency for many things we use - bluetooth, 802.11 wifi, xbee, etc. common in ISM band (microwaves are also in this space)

Industrial Scientific and Medical band - can't be licensed for commercial, short range use

in order to get high data rates, you need to use a high frequency (cell phone transmission) 1800-1900 GHz range

radios - 2.4-5.9 range (lower can be short range radios)

bluetooth - reliability, designed as a wire replacement, 1:1, works like TCP socket connections (radios must be paired before communication) multiple service profiles, different devices meet different profiles

zigbee - low power, flexible, mesh networks (reconfiguration of network on the fly), series 1 and 2, they can do both 1:1 and broadcast (XBEE), limitation of building up a stack… adding in error correction, lose opportunity to make real time transmissions (triangulations, can only get rough approximation of location)

radio is induction - received power (strength of signal) can let us know the distance

In summary: Datastack - easy to send data, hard to determine distance, addresses and a system of identification, transmission distance depends on power, 2 different types of radio (1:1 vs. broadcast)

xbee radios - 2 different protocols

  • pass-through modems - a device that converts data from one form into another
  • proprietary protocol that can send data about other pins on the chip (xbees have a microcontroller on board, you can read or set digital IO pins)

coolterm - another serial program

(bluetooth demonstration)

  • modem - data mode and command mode
  • i - inquiry scan
  • $$$ - start command mode
  • c [address] - make a connection
  • d - list of commands
  • h - full list of all commands

XBEE radios

  • set up some addressing in advance…
  • my address (my)
  • my destination address (dl)
  • personal area network (id)

9600 communication rate (1.1 Manual 2.5 Manual)

  • +++ and wait (no return), wait for OK
  • ATMY (my address) (AT commands show info)
  • ATDL
  • ATID
  • ATRE - reset all factory defaults
  • ATID1111 (set address of 1111)
  • ATWR - write to non-volatile memory
  • ATCN - go back into data mode

sticker each XBEE so you know which is which

+++ in XBEE times out after a few seconds of inactivity, so type commands quickly!!

  • +++ (wait)
  • ATID1111,
  • MY1,
  • DL2,
  • WR
  • ATCN

Setting up datapins

  • ATD0
  • ATD1
  • ATD2 etc
  • 0 is off
  • 1 digital in
  • 2 analog in
  • etc. (lookup in table, see links above)

the receiver should be set to the defaults (make sense, no transmissions)

FINAL PROJECT conversation