ZigBee Based Wireless Sensor Networks
P06501
Introduction
Team Members EE: Jared Titus, Brandon Good, Nick
Yunker CE: Ryan Osial, Justin Thornton
Coordinator Dr. Reddy
Mentor Dr. Hu
Sponsors Sensorcon PCB Express
Needs Assessment Problem:
Crossbow Technology provides wireless sensor motes but cost deters the creation of large networks.
Budget: $1000 for parts, fabrication, and
assembly Solution:
Create low cost ZigBee Data Forwarding Unit (DFU) hardware and software prototype
ZigBee Standard
Low-power Low-cost Built on IEEE 802.15.4 standard Defines the protocols for creating
self-organizing mesh networks Three types of devices:
ZigBee Coordinator, Full-Function Device (FFD), and Reduced-Function Device (RFD)
ZigBee DFU Requirements Motes shall connect to sensors through
Interrupt and Analog-Digital Converter (ADC) connections
Motes shall be battery powered or USB powered. A RFD should be able to operate autonomously for three months
Motes shall be less than 9 sq. inches In volume production (>5000 units)
motes should cost less than $20 Motes shall form a bi-directional mesh
network.
ZigBee DFU Requirements Motes shall interface to a PC via USB Motes shall support adjustable
periodic data reporting, threshold reporting, and querying of data
A Graphical User Interface (GUI) shall allow the user to monitor and control the network
ZigBee DFU hardware shall support Coordinator, FFD, and RFD software.
Concept Design 3 Different Designs were considered Concept 1: Custom Hardware (Microcontroller and RF
Transceiver) with TinyOS networking stack Concept 2: Custom Hardware (Microcontroller and RF
Transceiver) with Custom ZigBee stack Concept 3: Custom Hardware (SoC) with a proprietary
ZigBee stack
Abstract Custom Hardware Designs
Atmega 128 Chipcon 2420
2.4
GH
z A
ntF
TD
I 232
Mote
UartLines
SPIInterface R
F S
igna
l
Ember250 - SOC
2.4
GH
z A
ntF
TD
I 232
Mote
UartLines R
F S
igna
l
Concept Pros and Cons
Concept 1 Concept 2 Concept 3
Pros -Low Cost-Open Development
-Low Cost-Open Development-More network control
-Vendor provided Stack-Less Hardware
Cons -No standardizing body-Not Zigbee Compliant-Complicated Layout
-Very Complicated Software-Complicated Layout
-Less network control-Untested SoC Solution-Cost of Stack
Feasibility Selected Viable Concepts to Analyze Created Pugh Matrix
Chose Evaluation Criteria based on: Requirements Time and cost to implement
Created Criteria Weighting Matrix Applied Weights to Each Criteria Selected Final Design based on Weighted
Pugh Ember – 100% Custom Stack – 87.1% Crossbow MicaZ and Software – 85.9% TinyOS + Berkley HW Design – 79.5%
Hardware
Power Switcher System on Chip (SoC) Antenna with Balun Impedance
Matching USB–UART Bridge Sensor Board
Power Switcher
Switches between USB 3.3V and battery 3V source when plugged into or disconnected from a computer
Enable signal provided by EM250 chip controls switching
TI Dual pair CMOS 4007 chip used in implementing this circuit.
M1
MbreakN
M2 MbreakN
M3MbreakN
M4
MbreakP
M5MbreakP
M6 MbreakP
USB 3.3V
MCU ENABLE
BATTERY 3V
0
C15pF
OUT
System on Chip (SoC)
Ember 250 System on Chip used. Integrates Microcontroller, 2.45GHz
ZigBee Transceiver, 128kB flash memory and 5kB SRAM into one compact 5mm x 5mm package.
Antenna with Balun Circuit
Antenna Factor 2.45GHz antenna. 6.5mm x 2.5mm SMT packaging allows for
compact MOTE design without a large whip antenna.
Balun circuit matches the 200Ω characteristic impedance of EM250 to 50Ω Antenna Impedance.
E 1A N TE N N A
C 65 p F
C 5
. 7 5 p F
C 7. 7 5 p F
1 2L 2
7 . 5 n H1
2
L 33 . 9 n H
1
2
L 47 . 5 n H
1 . 8 V
G N D
R F _ I N _ P
R F _ I N _ N
USB–UART Bridge
Allows for USB connection between PC and EM250 chip by use of a virtual communications port
FTDI communicates with EM250 using UART Provides power from USB when connected
Sensor Board
Integrates 2 Analog Devices temperature sensors and 1 light sensor.
Light sensor used to wake up MCU from sleep. Dual temp sensors used to show that multiple
analog sensors can be used on one MOTE.
Interfaces
USB/RS-232 Virtual Comm Port (VCP)
Universal Asynchronous Receiver-Transmitter (UART)
Serial Interface (SIF) Flash Programming and Real Time
Debugging of Ember EM250 Sensor Board Interface
8 pin interface between Sensor Board and Mote
3 pairs of Data/Enable, Vcc, and GND
Microcontroller SoftwareInitialize Stage
(Hardware/Serial Comm.)
Initialize Network Stack
Join Network
Configure Defaults
Sleep for X (sec)
Need to Transmit?
Send Data
Listen for Messages for X (sec)
Received New Data?
No
Update Config
Yes
Yes
No
Reduced Function Device(ZigBee End Device – ZED)
Microcontroller SoftwareInitialize Stage
(Hardware/Serial Comm.)
Initialize Network Stack
Join Network
Configure Defaults
Message Received?
Send Data
Update Config
Listen/Wait
Interrupt Occur?
Message for Me?
Yes
No
Need to Send Data?
Yes
No
Yes
No
Yes
No
Full Function Device(Zigbee Router – ZR)
Microcontroller SoftwareInitialize Stage
(Hardware/Serial Comm.)
Initialize Network Stack
Start Network
Configure Defaults
Listen/Wait
Message Received
Determine Desitination
Send Data to Host Computer
Send Data to Zigbee Device
Update Self/Network
Coordinator(Zigbee Coordinator – ZC)
Network Design Coordinator
Gatekeeper to network Routes Packets
Router Routes Packets Queues data for sleeping End Device
End Device Sleeps when inactive Queries parent for data
Network Design contd. Packet Routing
Ad-hoc On-demand Distance Vector (AODV)
Determines path though network inreal-time
Assumes that nodes may leave network at any time
Uses Link-Quality-Indicator (LQI) and number of hops as a selection metric
PC to Mote Messages Report Rate Polling Rate ADC Sampling Threshold
Boundary Query Node Data Get Routing
Table Reset Change Power
Profile
Command Message Layer
Command Header Layer
Source-Destination Layer
Serial Interface Layer
USB Interface Layer
Mote to PC Messages Coordinator
Routing Table Sensor Data
Data Layer
Data Header Layer
Source-Destination Layer
Serial Interface Layer
USB Interface Layer
GUI – Main Form Shows the Network Status Shows the Alerts in the Network Controls the other Network Views
Network Topology Mote Parameter Tree Mote Sensors
GUI – Network Topology Form
Displays all the mote in the network Shows all the communication paths
between the motes Mote placement on the form can be
rearranged. Sensor Data can be displayed for
motes
GUI – Mote Tree Form Displays the parameter values for
each mote in the network. Update parameter values for a
mote/motes
GUI – Mote Sensor Form Displays the sensor data for each mote
in the network.
Test Plan A test procedure was written for each
requirement of the project.
Example Test ProcedureRequirement 3.5Description: Motes shall have a minimum of 3
months autonomous operation on battery power supply
Test Plan:1. Place current probes between the battery and mote.2. Turn on the mote and allow it to perform normal
network operations3. Measure the average current draw.4. Divide the power of the battery (mAh) by the
average current draw to find the hours in which it can operate
Implementation Plan Week by week breakdown of what will be accomplished in SDII
Week 1: Star Networking on Dev boards Multihop on Dev boards
Week 2: Initial GUI milestone 1 (partial implementation) Initial firmware to Motes
Week 3: GUI milestone 2 (less network topology displayed) Star Networking on Motes Multihop on Motes Basic Mesh networking on Dev Boards
Week 4: Basic Power Management implemented (mote operation only) Basic Mesh Networking on Motes
Week 5: GUI completed
Week 6: Full Mesh Networking on ZigBee DFU completed
Week 7: Power management implemented (fully for mote)
Week 8: Testing and documentation
Week 9/10: Design/Project Completed IEEE regional Senior Design Competition
Bill of Materials Budget
$1000 from Sensorcon Ember Development Kit - $2500
Donation from Mark Wagner (Sensoncon)
Total Cost for 10 Motes - $176.07 Total Cost for Additional Items -
$360.01 Total Project Cost - $536.08 Each mote costs ~$21 to build
(with EM250)
ZigBee DFU
Questions ?