Wireless Sensor Networks: The Sensor Node

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Wireless Sensor Networks The Sensor Node

• By Nachiket Kale
• 02D07002

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The Basic Element Of Wireless Sensor Networks A
Sensor Node

• Transducer to sense
• Processor and memory to compute
• Modem and a transceiver to communicate
• Power supply

MEMORY
TRANSCEIVER
OBJECT
A D C
TRANSDUCER
MODEM
PROCESSOR
POWER SUPPLY
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Design approach chosen COTS design

• Interfacing commercially available components
• Intelligent multilayered PCB design to reduce
  form factor (Size A cubic inch)
• Pros Less time intensive design, TinyOS
  compatibility, easy to upgrade
• Cons Large size, high power consumption, higher
  cost per unit

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Indriya Series Block Diagram
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Indriya Series Key Components

• Microcontroller ATmega2560
• Low power AVR 8 bit Microcontroller
• 256Kb self-programmable flash
• 4Kb EEPROM, 8Kb SRAM
• 16 channel 10 bit ADC
• JTAG interface

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Indriya Series Key Components

• Transceiver AT86RF230
• 2.4 GHz band Transceiver
• ZIGBEE compliant
• Low Current Consumption
• (0.1 uA in sleep mode, 17/16mA in Tx/Rx mode)
• Typical Bit Rate 250 Kbps

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Indriya Series Key Components

• USB interface FT232R
• Single chip USB to UART interface
• Data-rates 300 to 1M baud
• Bus powered/Self powered configurations
• Memory ATMELs AT49 series
• 1Mbyte to 64Mbyte memory

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Indriya Series Description

• IN order to achieve programming flexibility,
  multiple designs were created
• The three designs
• USB to SPI interface
• SPI programmed
• JTAG interfaced
• Designed library functions of all the components
  involved

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Indriya1.1 Schematic
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Indriya1.2 Schematic
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Indriya1.3 Schematic
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PCB fabrication roadblocks

• All PCBs almost complete, 2 pre fabrication
  roadblocks
• ATmega2560 and AT86RF230 delivery still awaited
• Smd Ceramic crystal
• SMD Balun component order to be placed

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Programming dongle

• Program
• the uC by
• JTAG or SPI
• interface
• USB/TxRx
• programming
• Needs code
• burnt in uC

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Memory

• Three designs
• Indriya on board design
• Indriya interface board
• MICA mote interface board
• 64MB Flash memory requires 22 address lines, 16
  data lines
• Read, Write and Chip Enable handshake
• 3 ports required

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Ping Pong Buffering

• Hardware ping pong
• Twice the number of ports
• 3 pin reconfiguration required
• Higher component cost, energy cost
• The solution is software ping pong using single
  memory interface

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Steps to be taken

• Press ATMEL order
• Buy all residual components (smd resistors,
  capacitors, LEDs, etc)
• Check MICA mote 51 pin connector pinout
• Design PCB for MICA mote memory interface
• Send PCB for fabrication

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Thank You!