TinyOS 2.0 Network Stack Enhancements

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TinyOS 2.0Network Stack Enhancements

• Joseph Polastre Phil Levis
• UC Berkeley UC BerkeleyMoteiv Corporation

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Need for changes

• Cross-platform common radio/MAC
• micaZ, Telos, imote2
• Currently each platform implements routines for
  accessing radio and timer
• Support different TOSMsg structures for different
  radios/MACs
• Difficult to build different underlying MAC and
  Radio implementationsCSMA/TDMA/slotted

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Summary of Changes

• New TOSMsg format
• Defined by each radio
• External typesnetwork structures
• Abstract typefields provided by components
• New Interfaces to AM Layer
• Supports CSMA and slotting MAC protocols
• New Bus Protocol Abstraction

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TOSMsg

• Abstract type defined by each MAC protocol
• Similar to S-MAC TinyOS implementation

Radio/MAC specific header
typedef nx_struct TOSMsg TOSRadioHeader
header nx_uint8_t dataTOSH_DATA_LENGTH
TOSRadioFooter footer TOSRadioMetadata
metadata TOSMsg
Application data payload
Radio/MAC specific footer
Radio/MAC metadatanot sent over the radio
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Global TOSMsg Fields

• Interface RadioPacket
• Length
• Address
• Group/PAN
• Data
• Time
• Acknowledgement

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Accessing TOSMsg Fields

• For Global Fields
• Platform and MAC independent
• All MAC required to implement
• Wire to RadioC.RadioPacket
• Access fields through Radio Packet interface

length call RadioPacket.getLength(msg)
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Moving up the stack

• RadioPacket accesses the lowest primitive fields
  at the link protocol
• AM exports fields throughAMPacket
• Likewise, standard MultiHopfields through
  MultiHopPacket
• Provides separation of messagefield
  implementation and accessto those fields

MultiHop
AM
Radio
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Accessing TOSMsg Fields

• For MAC-dependent applications
• Use structures defined by MAC protocol
• Example CC2420 radio

void myfunc() if (msg.lqi gt 100) //
perform action
typedef nx_struct TOSRadioMetadata nx_uint8_t
strength nx_uint8_t lqi nx_bool crc
nx_bool ack nx_uint16_t time
TOSRadioMetadata
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Protocol Bus Abstraction

• All protocol busses provide Bus Arbitration
• SPI, I2C, UART
• HIL Protocol Access
• Bus must be acquired before use, even if only a
  single user
• Token granted to bus user, all accesses must use
  token

Bus Arbitration
HIL SPI
StdControl
SPIC
SPI Configuration
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Component OrganizationExample CC2420 Radio
Stack for Telos
Platform Independent
Platform Specific
All radios provide
RadioC

CSMARadioC

Adds CSMA interfaces
CC2420RadioM
CC2420ControlM

CC2420 Logic
HPLCC2420

Rd/Wr CC2420 Registers
TelosCC2420

Wiring to SPI bus/Ints
HIL SPI

SPI Bus Interface
MCU Implementation
HAL Interrupts Pins
HAL SPI

HPL MCU

MCU Registers
Hardware
MCU Radio
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Questions?

• More information
• See TEP 105
• Radio Link Layer