lecture-7-cho_pte587_sensornet1-feb-24-2011

5ma acve 16ma idle 1ua powered down ds2401 unique id

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Unformatted text preview: ks USC  ­ PTE587 Example: ad hoc, multi-hop routing of photo sensor readings 3450 B code 226 B data Graph of cooperating state machines on shared stack 23 Other Sooware •  Communica;on –  MACs –  Rou;ng Algorithm –  Applica;on Specific Algorithms •  Sooware Design –  Very low ­level and detailed planning –  Improving as everything becomes smaller and faster –  Some capable of running embedded Linux 3/2/11 USC  ­ PTE587 24 System Analysis •  Aoer Building Applica;ons –  System is highly memory constrained –  Communica;on bandwidth is limited by CPU overhead at key ;mes. –  Communica;on has bursty phases. •  Where did the Energy/Time go? –  50% of CPU used when searching for packets –  With 1 packet per second, >90% of energy goes to RX! 3/2/11 USC  ­ PTE587 25 Challenges 3/2/11 USC  ­ PTE587 26 Problems •  Imbalance between memory, I/O and CPU –  Increase memory (Program and Data) by selec;ng different CPU •  Time/energy spent wai;ng for recep;on –  Solu;on: Low ­power listening sooware protocols •  Peak CPU usage during transmission –  Solu;on: Hardware based communica;on accelerator 3/2/11 USC  ­ PTE587 27 The MICA architecture 51-Pin I/O Expansion Connector 8 Programming Digital I/O 8 Analog I/O Lines –  –  –  –  4 Mhz 8 ­bit CPU 128KB Instruc;on Memory 4KB RAM 5.5mA ac;ve, 1.6mA idle, <1uA powered down DS2401 Unique ID Transmission Power Control •  4 Mbit flash (AT45DB041B) –  SPI interface –  1 ­4 uj/bit r/w Atmega103 Microcontroller Hardware Accelerators TR 1000 Radio Transceiver •  RFM TR1000 radio SPI Bus •  Atmel ATMEGA103 Coprocessor 4Mbit External Flash Power Regulation MAX1678 (3V) –  50 kb/s – ASK –  Communica;on focused hardware accelera;on •  Network programmable •  51 ­pin expansion connector –  Analog compare + interrupts •  GCC based tool/programming chain 2xAA form factor 3/2/11 USC  ­ PTE587 Cost-effective power source 28 Power Op;miza;on Challenge Scenario: •  1000 node mul; ­hop network •  Deployed network should be “dormant” un;l RF wake ­up signal is heard •  Aoer sleeping for hours, netw...
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