Zigbee based wireless sensor networks
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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:

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  • 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
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
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
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 requirements1
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
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


  • 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%


  • Power Switcher

  • System on Chip (SoC)

  • Antenna with Balun Impedance Matching

  • USB–UART Bridge

  • Sensor Board

Power switcher
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.

System on chip soc
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 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.

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
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.


  • 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 software
Microcontroller Software

Reduced Function Device

(ZigBee End Device – ZED)

Microcontroller software1
Microcontroller Software

Full Function Device

(Zigbee Router – ZR)

Microcontroller software2
Microcontroller Software


(Zigbee Coordinator – ZC)

Network design
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
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
PC to Mote Messages

  • Report Rate

  • Polling Rate

  • ADC Sampling

  • Threshold Boundary

  • Query Node Data

  • Get Routing Table

  • Reset

  • Change Power Profile

Mote to pc messages
Mote to PC Messages

  • Coordinator Routing Table

  • Sensor Data

Gui main form
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
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
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
GUI – Mote Sensor Form

  • Displays the sensor data for each mote in the network.

Test plan
Test Plan

  • A test procedure was written for each requirement of the project.

  • Example Test Procedure

    Requirement 3.5

    Description: 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 operations

    3. 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
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
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
ZigBee DFU

Questions ?