TinyOS 2.0 Network Stack Enhancements

1. TinyOS 2.0Network Stack Enhancements Joseph Polastre Phil Levis UC Berkeley UC BerkeleyMoteiv Corporation

2. 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 implementations—CSMA/TDMA/slotted

3. Summary of Changes • New TOSMsg format • Defined by each radio • “External types”—network structures • Abstract type—fields provided by components • New Interfaces to AM Layer • Supports CSMA and slotting MAC protocols • New Bus Protocol Abstraction

4. 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 data[TOSH_DATA_LENGTH]; TOSRadioFooter footer; TOSRadioMetadata metadata; } TOSMsg; Application data payload Radio/MAC specific footer Radio/MAC metadatanot sent over the radio

5. Global TOSMsg Fields • Interface RadioPacket • Length • Address • Group/PAN • Data • Time • Acknowledgement

6. 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);

7. 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

8. Accessing TOSMsg Fields • For MAC-dependent applications • Use structures defined by MAC protocol • Example: CC2420 radio typedef nx_struct TOSRadioMetadata { nx_uint8_t strength; nx_uint8_t lqi; nx_bool crc; nx_bool ack; nx_uint16_t time; } TOSRadioMetadata; void myfunc() { if (msg.lqi > 100) { // perform action } }

9. 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 StdControl HIL SPI Bus Arbitration SPIC SPI Configuration

10. Platform Independent Platform Specific Component OrganizationExample: CC2420 Radio Stack for Telos 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 SPI HAL Interrupts & Pins HPL MCU MCU Registers Hardware MCU & Radio

11. Questions? More information: See TEP 105: “Radio Link Layer”