TinyOS 2.0Network Stack Enhancements

Joseph Polastre Phil LevisUC Berkeley UC BerkeleyMoteiv Corporation

2TinyOS Technology Exchange II: 2/11/2005

Need for changes

Cross-platform common radio/MACmicaZ, Telos, imote2…Currently each platform implements routines

for accessing radio and timer Support different TOSMsg structures for

different radios/MACsDifficult to build different underlying MAC and

Radio implementations—CSMA/TDMA/slotted

3TinyOS Technology Exchange II: 2/11/2005

Summary of Changes

New TOSMsg formatDefined by each radio“External types”—network structuresAbstract type—fields provided by components

New Interfaces to AM LayerSupports CSMA and slotting MAC protocols

New Bus Protocol Abstraction

4TinyOS Technology Exchange II: 2/11/2005

TOSMsg

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

typedef nx_struct TOSMsg { TOSRadioHeader header; nx_uint8_t data[TOSH_DATA_LENGTH]; TOSRadioFooter footer; TOSRadioMetadata metadata;} TOSMsg;

Radio/MAC specific header

Application data payload

Radio/MAC specific footer

Radio/MAC metadatanot sent over the radio

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Global TOSMsg Fields

Interface RadioPacketLengthAddressGroup/PANDataTimeAcknowledgement

6TinyOS Technology Exchange II: 2/11/2005

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);

7TinyOS Technology Exchange II: 2/11/2005

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

Radio

AM

MultiHop

8TinyOS Technology Exchange II: 2/11/2005

Accessing TOSMsg Fields

For MAC-dependent applicationsUse structures defined by MAC protocol

Example: CC2420 radio

void myfunc() { if (msg.lqi > 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;

9TinyOS Technology Exchange II: 2/11/2005

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 ArbitrationHIL SPIStdControl

SPICSPI Configuration

10TinyOS Technology Exchange II: 2/11/2005

Component OrganizationExample: CC2420 Radio Stack for Telos

RadioC

CSMARadioC

CC2420RadioM CC2420ControlM

HPLCC2420

HIL SPI

HAL Interrupts & PinsHAL SPI

HPL MCU

Hardware

TelosCC2420

All radios provide

Adds CSMA interfaces

CC2420 Logic

Rd/Wr CC2420 Registers

Wiring to SPI bus/Ints

SPI Bus Interface

MCU Implementation

MCU Registers

MCU & Radio

Platform Independent Platform Specific

Questions?

More information:See TEP 105:“Radio Link Layer”