Wireless Sensor Networks Author: Matthias Wagner / Albert Martinez - PowerPoint PPT Presentation

Wireless Sensor Networks Author: Matthias Wagner / Albert Martinez M. Schubert, OTH Regensburg, Germany

Course structure 1.#lecture# 2.#lecture# 3.#lecture# Clock,# SimpliciTI# RF#basics# GPIO,Timer# protocol# Data# storage,# SPI,#UART# MRFI#chat# Project# 2 WSN || Matthias Wagner

WSN: Timetable 2015 Nr: 1 2 3 4 5 6 7 8 9 10 11 date: 18.03.15 26.03.15 01.04.15 08.04.15 15.04.15 22.04.15 29.04.15 06.05.15 13.05.15 20.05.15 27.05.15 Intro Intro Intro address Non 11:45 - Clocks Exam Intro WSN practical Flash practical MRFI LQI practical transmiss volatile 13:15 GPIO training 1 training 2 training 3 ion objects First steps Non 13:30 - ADC Simple peer to Range Q&A team up / project UART SPI MRFI CRC RSSI volatile 15:00 Timer Chat peer extender project setup objects Room: S159 S081 group name poject 1: 1 Intro WSN part 1 2: Intro 1: 2 part 2 2: practical Intro 1: 3 part 3 practical 2: training 2 Intro 1: 4 2: practical 1: Exam 5 2: 1: 6 2: 1: 7 2: 1: 8 2: 1: 9 2: 1: 10 2: 3 WSN || Matthias Wagner

Project • Group of 2 – 4 students • Minimun of two MSP430 boards • Documentation + Code • Presentation 4 WSN || Matthias Wagner

Wireless sensor networks (WSN) A Wireless sensor network (WSN ) can be defined as a network of devices, denoted as nodes, which can sense the environment and communicate the information gathered from the monitored field (e.g., an area or volume) through wireless links Chiara Buratti, Andrea Conti, Davide Dardari and Roberto Verdone 2009 ISSN 1424-8220

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Applications Environment# Health#Care# ! ! Air#and#water#quality# Blood#glucose# ! ! Sea#temperature# Heart#rate# ! ! ErupLon#monitoring# ! Commercial#use# Home#Intelligence# ! ! ! Customer#tracking# ! Smart#Home# AdverLsement # ! ! Light#sensor#/#switch#(WSAN)# Military # ! 8 WSN || Matthias Wagner

Sensor Module / Node Power Unit Battery Processing Unit Sensing Unit Communication Unit Microcontroller ADC / Sensor Radio Digital Bus Memory RAM / SD 9 WSN || Matthias Wagner

Network 10 WSN || Matthias Wagner

CC430 target board • CC430F6137 • microSD card • UART • SPI • push button 11 WSN || Matthias Wagner

CC430F6137 • 16 bit Microcontroller • 20 MHz maximal frequency • 32 kB of Flash memory • 4 kB RAM • 44 GPIO • 2x 16 bit Timers • 10 and 12 bit ADC • 128 Bit AES Security Encryption Coprocessor • Communication via UART, SPI and I 2 C 12 WSN || Matthias Wagner

Integrated CC1101 • sub 1 GHz Transceiver • 300 – 928 MHz Freqency band • Programmable data rate from 0.6 to 600 kbps • Low power consumption (14.7 mA in RX mode) • High Sensitivity 13 WSN || Matthias Wagner

Low Power Modes • Active mode: • LPM0 : SMCLK and ACLK active. CPU and MCLK disabled • LPM1 : ACLK is active. CPU, MCLK are disabled. SMCLK depend • LPM2 : DC generator and ACLK active. CPU, MCLK, SMCLK, DCO are disabled • LPM3 : ACLK active. CPU, MCLK and SMCLK disabled • LPM4 : CPU and all clocks disabled 14 WSN || Matthias Wagner

SPI and I2C • Universal Serial Communication Interface (USCI) • Synchronous communication 15 WSN || Matthias Wagner

UART • Universal Asynchronous Receiver Transmitter • Asynchronous communication • USB Serial Adapter • Terminal program 16 ! WSN || Matthias Wagner

Wireless data transmission Data transmission via electromagnetic radioation 17 WSN || Matthias Wagner

isotropic radiator 18 WSN || Matthias Wagner

Free-space path loss 19 WSN || Matthias Wagner

Received energy 1 10 100 0,1 0,01 433 MHz 915 MHz 0,001 1 ⋅ 10-4 2.4 GHz 1 ⋅ 10-5 1 ⋅ 10-6 1 ⋅ 10-7 1 ⋅ 10-8 20 WSN || Matthias Wagner

Signal modulation OOK : On Off keying AM: Amplitude modulation FM: Frequency modulation 21 WSN || Matthias Wagner

2-FSK: Frequency Shift keying 4-FSK, GFSK MSK: Minimum Shift keying QAM, FSK, ASK 22 WSN || Matthias Wagner

base frequency bands ISM SRD Industrial, Scientific and Medical Band Short Range Devices 433 MHz 433 MHz Region 1 (Europa, Africa) 868 MHz 902 MHz Region 2 (America) some ranges at 2,45 GHz 2,4 GHz (typically limited to 25-100 mW ERP) 23 WSN || Matthias Wagner

24 WSN || Matthias Wagner

SimpliciTI RF protocol for MSP430 microcontrollers • handling network traffic • routing/forwarding messages • data encryption • CRC • data whitening 25 WSN || Matthias Wagner

Architecture Topologies: • Peer-to-Peer • Star Topology Types of devices: • Access Point (AP) • End Device (ED) • Range Extender (RE) 26 WSN || Matthias Wagner

SimpliciTI Layers vs OSI ! 27 WSN || Matthias Wagner

28 http://www.inetdaemon.com/tutorials/basic_concepts/network_models/osi_model/osi_and_internet_protocols.shtml

Data Link/Physical layer • Board Support Package (BSP): minimal support to a specific microcontroller • Minimal RF Interface (MRFI): communication with the radio chip 29 WSN || Matthias Wagner

Transmission Frequencies RF Transmission Frequencies base freq. : 820MHz 0 1 2 3 4 channel spacing Power 819,9 820 820,1 820,2 820,3 820,4 820,5 820,6 820,7 820,8 820,9 821 30 MHz WSN || Matthias Wagner

Power settings ! 31 WSN || Matthias Wagner

Cyclic Redundancy Check (CRC) • Detect accidental change of data during transmission • A short check value gets attached to the message • The attached value is the remainder of a polynomial division 32 WSN || Matthias Wagner

Received Signal Strength Indicator (RSSI) • Indicates the power received in a transmission • The MRFI_Rssi() function provides the RSSI value • Often used to detect the noise in a specific channel 33 WSN || Matthias Wagner

Clear Channel Assessment (CCA) Algorithm to minimize collisions between radios: • Check a channel for a very shot time • Compare the noise in the channel with the noise of a transmission • If there is no transmission in this channel send the data • If the channel is occupied then wait for a while and repeat the process 34 WSN || Matthias Wagner

MRFI frame • mrfiPacket_t mrfiPacket_t : is a structure which contains two type definitions Packet.frame : frame of data a) a) Packet.frame Length (1B) Source (4B) Destination (4B) Payload (Length-8 bytes long) Packet.rxMetrics : statistics on the last received packet b) b) Packet.rxMetrics CRC RSSI (1B) LQI (7b) (1b) • void MRFI_RxCompleteISR() void MRFI_RxCompleteISR() : received packet interrupt 35 WSN || Matthias Wagner

API of Data Link/Physic Layer • BSP_INIT(void) • BSP_Delay(uint16_t usec) • BSP_EARLY_INIT(void) • MRFI_Init(void) • MRFI_Transmit(mrfiPacket_t * pPacket, uint8_t txType) • MRFI_Receive(mrfiPacket_t * pPacket) • Mrfi_RxModeOn(void) • MRFI_RxOn(void) 36 WSN || Matthias Wagner

API of Data Link/Physic Layer • Mrfi_RxModeOff(void) • MRFI_RxIdle(void) • MRFI_Sleep(void) • MRFI_WakeUp(void) • int8_t MRFI_Rssi(void) • uint8_t MRFI_RandomByte(void) • Mrfi_DelayUsec(uint16_t howLong) • MRFI_GetRadioState(void) 37 WSN || Matthias Wagner

NWK Layer • NWK : connecting two different peers and selecting the proper route • APP NWK : manage network as an internal peer to peer object 38 WSN || Matthias Wagner

SimpliciTI frame PREAMBLE Radio synchronization PORT Forwarded frame (7), Encryption context (6) Application port number (5-0 SYNC Radio synchronization DEVICE INFO Sender/receiver and platform capabilities LENGTH Length of remaining packet in bytes TRACTID Transaction id MISC Miscellaneous frame fields APP PAYLOAD Application data DST ADDR Destination address FCS Frame Check Sequence SRCADDR Source address 39 WSN || Matthias Wagner

secure SimpliciTI frame 40 WSN || Matthias Wagner

API of NWK • SMPL_Init • SMPL_Link • SMPL_Unlink • SMPL_LinkListen • SMPL_Send • SMPL_SendOpt • SMPL_Receive • SMPL_Ping 41 WSN || Matthias Wagner

API of NWK SMPL_Ioctl: change configuration parameters while run time • Frequency • Radio • Encryption • Access to current connection • Firmware and protocol characteristics • AP nwk mgmt control 42 WSN || Matthias Wagner