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ICC 2012 – E2NETS workshop                                                              OTTAWA – CANADA – JUNE 10-15 2012E...
ICC 2012 – E2NETS workshop                                                OTTAWA – CANADA – JUNE 10-15 2012Agenda•   Intro...
ICC 2012 – E2NETS workshop                                                         OTTAWA – CANADA – JUNE 10-15 2012Introd...
ICC 2012 – E2NETS workshop                                                   OTTAWA – CANADA – JUNE 10-15 2012Objective•  ...
ICC 2012 – E2NETS workshop                                                OTTAWA – CANADA – JUNE 10-15 2012Agenda•   Intro...
ICC 2012 – E2NETS workshop                                             OTTAWA – CANADA – JUNE 10-15 2012HW platform• TI MS...
ICC 2012 – E2NETS workshop                                                    OTTAWA – CANADA – JUNE 10-15 2012SW stack Co...
ICC 2012 – E2NETS workshop                                                    OTTAWA – CANADA – JUNE 10-15 2012SW stack Da...
ICC 2012 – E2NETS workshop                                                OTTAWA – CANADA – JUNE 10-15 2012Agenda•   Intro...
ICC 2012 – E2NETS workshop                                                          OTTAWA – CANADA – JUNE 10-15 2012Power...
ICC 2012 – E2NETS workshop                                                         OTTAWA – CANADA – JUNE 10-15 2012SW-sta...
ICC 2012 – E2NETS workshop                                                             OTTAWA – CANADA – JUNE 10-15 2012Wa...
ICC 2012 – E2NETS workshop                                               OTTAWA – CANADA – JUNE 10-15 2012Agenda•   Introd...
ICC 2012 – E2NETS workshop                                                            OTTAWA – CANADA – JUNE 10-15 2012Sta...
ICC 2012 – E2NETS workshop                                                            OTTAWA – CANADA – JUNE 10-15 2012Sta...
ICC 2012 – E2NETS workshop                                                            OTTAWA – CANADA – JUNE 10-15 2012Sta...
ICC 2012 – E2NETS workshop                                                    OTTAWA – CANADA – JUNE 10-15 2012Standby mod...
ICC 2012 – E2NETS workshop                                                    OTTAWA – CANADA – JUNE 10-15 2012Standby mod...
ICC 2012 – E2NETS workshop                                                      OTTAWA – CANADA – JUNE 10-15 2012Standby m...
ICC 2012 – E2NETS workshop                                                   OTTAWA – CANADA – JUNE 10-15 2012Sleep mode i...
ICC 2012 – E2NETS workshop                                                  OTTAWA – CANADA – JUNE 10-15 2012Sleep mode im...
ICC 2012 – E2NETS workshop                                                  OTTAWA – CANADA – JUNE 10-15 2012Hibernation m...
ICC 2012 – E2NETS workshop                                                  OTTAWA – CANADA – JUNE 10-15 2012Hibernation m...
ICC 2012 – E2NETS workshop                                                OTTAWA – CANADA – JUNE 10-15 2012Agenda•   Intro...
ICC 2012 – E2NETS workshop                                                   OTTAWA – CANADA – JUNE 10-15 2012Characteriza...
ICC 2012 – E2NETS workshop                                                OTTAWA – CANADA – JUNE 10-15 2012Experimental re...
ICC 2012 – E2NETS workshop                                                 OTTAWA – CANADA – JUNE 10-15 2012Conclusions• U...
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Ultra-Low-Power Wireless Sensor Node Programmable in Java

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Slides presented on June 11 2012 in Ottawa, at IEEE ICC 2012.

Open-hardware open-source architecture of a wireless sensor node that features an ultra-low-power microcontroller unit (MCU) completely programmable in Java.

All the low-power modes of the MCU are directly exploitable from the Java-compatible runtime environment.

Published in: Technology, Business
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Ultra-Low-Power Wireless Sensor Node Programmable in Java

  1. 1. ICC 2012 – E2NETS workshop OTTAWA – CANADA – JUNE 10-15 2012E2NETS WorkshopEnergy Efficiency in Wireless Networks & Wireless Networks for Energy Efficiency Ultra-Low-Power Sensor Nodes Featuring a Virtual Runtime EnvironmentEMANUELE LATTANZI ALESSANDRO BOGLIOLODiSBeF University of Urbino & NeuNet 1/25 alessandro.bogliolo@uniurb.it
  2. 2. ICC 2012 – E2NETS workshop OTTAWA – CANADA – JUNE 10-15 2012Agenda• Introduction• HW-SW platform• Power states• DPM issues and solutions• Experimental results 2/25 alessandro.bogliolo@uniurb.it
  3. 3. ICC 2012 – E2NETS workshop OTTAWA – CANADA – JUNE 10-15 2012Introduction• Need for energy efficient wireless sensor nodes – Lifetime maximization – Compatibility with energy harvesters• Attractiveness of runtime virtual environment – Development – Deployment – Re-use/Re-programming• Availability of ultra-low-power micro controller units (MCUs) featuring – 16-bit RISC architectures clocked at tens of MHz – 16kbytes of main memory – 64kbytes of flash memory – Voltage-frequency scaling – Low-power modes with sub-ms wake-up time 3/25 alessandro.bogliolo@uniurb.it
  4. 4. ICC 2012 – E2NETS workshop OTTAWA – CANADA – JUNE 10-15 2012Objective• Ultra-low power sensor node• Java-compatible virtual run-time environment• Full exploitation of low-power modes• Off-the-shelf low-cost components• Open-hardware PCB• Open-source software stack 4/25 alessandro.bogliolo@uniurb.it
  5. 5. ICC 2012 – E2NETS workshop OTTAWA – CANADA – JUNE 10-15 2012Agenda• Introduction• HW-SW platform• Power states• DPM issues and solutions• Experimental results 5/25 alessandro.bogliolo@uniurb.it
  6. 6. ICC 2012 – E2NETS workshop OTTAWA – CANADA – JUNE 10-15 2012HW platform• TI MSP430F54xxa MCU – 16-bit RISC – 8.9mA @ 25MHz – 6 LP modes – 0.1-73 uA – 5us wake-up 6/25 alessandro.bogliolo@uniurb.it
  7. 7. ICC 2012 – E2NETS workshop OTTAWA – CANADA – JUNE 10-15 2012SW stack Contiki OS• Open-source real-time OS for sensor networks and networked embedded systems – Portability – Multi-tasking – Memory efficiency – Event-driven organization – Elementary DPM which exploits the stand-by state of the MCU and wakes it up every 10ms to keep timing coherence 7/25 alessandro.bogliolo@uniurb.it
  8. 8. ICC 2012 – E2NETS workshop OTTAWA – CANADA – JUNE 10-15 2012SW stack Darjeeling VM• Open-source VM for extremely limited devices – Java compatibility – Limited requirements (10kbytes of RAM) – Bytecode efficiency (infuser) – Runs as a single process – Supports multi-threading – Preemptive round-robin scheduling 8/25 alessandro.bogliolo@uniurb.it
  9. 9. ICC 2012 – E2NETS workshop OTTAWA – CANADA – JUNE 10-15 2012Agenda• Introduction• HW-SW platform• Power states• DPM issues and solutions• Experimental results 9/25 alessandro.bogliolo@uniurb.it
  10. 10. ICC 2012 – E2NETS workshop OTTAWA – CANADA – JUNE 10-15 2012Power modes CPU Clock MemoryActive mode    1-10mW Self wake up [1-10us]Standby mode    1-100uW External interrupt [<1ms]Sleep mode    1uWReboot at external interrupt [1-100ms]Hibernation mode    100nW 10/25 alessandro.bogliolo@uniurb.it
  11. 11. ICC 2012 – E2NETS workshop OTTAWA – CANADA – JUNE 10-15 2012SW-stack dimension OS VM Int OS VMActive boot boot hand sch sch VtaskStandbySleepHibernation 11/25 alessandro.bogliolo@uniurb.it
  12. 12. ICC 2012 – E2NETS workshop OTTAWA – CANADA – JUNE 10-15 2012Wake-up transitions OS VM Int OS VMActive boot boot hand sch sch VtaskStandbySleepHibernation 12/25 alessandro.bogliolo@uniurb.it
  13. 13. ICC 2012 – E2NETS workshop OTTAWA – CANADA – JUNE 10-15 2012Agenda• Introduction• HW-SW platform• Power states• DPM issues and solutions• Experimental results 13/25 alessandro.bogliolo@uniurb.it
  14. 14. ICC 2012 – E2NETS workshop OTTAWA – CANADA – JUNE 10-15 2012Standby mode Int OS VMContikiOS schedules hand sch sch Vtaska self-wakeupevery 10msThere are 3 cases:a) The VM has no tasks to resume a 14/25 alessandro.bogliolo@uniurb.it
  15. 15. ICC 2012 – E2NETS workshop OTTAWA – CANADA – JUNE 10-15 2012Standby mode Int OS VMContikiOS schedules hand sch sch Vtaska self-wakeupevery 10msThere are 3 cases:a) The VM has no tasks to resume aa) The OS has no proc. to resume b 15/25 alessandro.bogliolo@uniurb.it
  16. 16. ICC 2012 – E2NETS workshop OTTAWA – CANADA – JUNE 10-15 2012Standby mode Int OS VMContikiOS schedules hand sch sch Vtaska self-wakeupevery 10msThere are 3 cases:a) The VM has no tasks to resume aa) The OS has no processes to resume ba) The VM has a task to resume Actual wake up 16/25 alessandro.bogliolo@uniurb.it
  17. 17. ICC 2012 – E2NETS workshop OTTAWA – CANADA – JUNE 10-15 2012Standby mode abstract state diagramActive 1-10mW Vtask c Exploitation issues: a The self-loop longer than 10ms 1-10mW No power savingStandby b Not supported by the SW 1-100uW stack (VM always active) 1-10uW Not supported by Contiki OS Lack of timing infoStanby mode is not compatible with the SW stack! 17/25 alessandro.bogliolo@uniurb.it
  18. 18. ICC 2012 – E2NETS workshop OTTAWA – CANADA – JUNE 10-15 2012Standby mode improvements• Modified Contiki OS to make it able to dynamically adjust the INTERVAL of timer interrupts• Modified Darjeeling VM scheduler to make it able to set the OS timer and suspends the VM PROCESS_WAIT_EVENT_UNTIL()• Implemented a timed standby mode with just-in-time predictive wake-up• Mounted an external low-power (0.3uW) real-time clock (RTC) to preserve timing accuracy 18/25 alessandro.bogliolo@uniurb.it
  19. 19. ICC 2012 – E2NETS workshop OTTAWA – CANADA – JUNE 10-15 2012Standby mode modified state diagram 6.6mW Vtask 4.5uW + 153.72uJ/T Standby.a(T) Families of low-power states Standby.b(T) depending on T 4.5uW + 0.33uJ/T 4.5uW + 0.3uW Standby.t 4.5uW Standby 19/25 alessandro.bogliolo@uniurb.it
  20. 20. ICC 2012 – E2NETS workshop OTTAWA – CANADA – JUNE 10-15 2012Sleep mode issues• Unable to issue self-events – Wakup can only be triggered by external interrupts – Cannot be exploited if there are processes/tasks that need to resume at a given time (e.g., periodic monitoring tasks typical of many WSN applications)• Lack of timing information – No information about the time elapsed since last shut down – No time stamps associated with external interruptsSleep mode can ony be exploited in case of time- independent reactive applications 20/25 alessandro.bogliolo@uniurb.it
  21. 21. ICC 2012 – E2NETS workshop OTTAWA – CANADA – JUNE 10-15 2012Sleep mode improvements• Implemented a timed sleep mode with just in time predictive wakeup based on the external RTC• Used the external RTC to provide relative and absolute timing information at wake up 1.5uW + 0.3uW Sleep.t 1.5uW Sleep 21/25 alessandro.bogliolo@uniurb.it
  22. 22. ICC 2012 – E2NETS workshop OTTAWA – CANADA – JUNE 10-15 2012Hibernation mode issues• Unable to issue self-events – As for Sleep mode• Lack of timing information – As for Sleep mode• Lack of data retention – Requires a complete reboot – Impossible to resume a process/taskHibernation mode can ony be exploited in case of memory-less reactive applications 22/25 alessandro.bogliolo@uniurb.it
  23. 23. ICC 2012 – E2NETS workshop OTTAWA – CANADA – JUNE 10-15 2012Hibernation mode improvements• Used the external RTC as for the Sleep mode• Implemented a native method in the main of the VM to save and restore the heap of the VM in flash memory 1.5uW + 0.3uW Hibernation.t 1.5uW Hibernation 23/25 alessandro.bogliolo@uniurb.it
  24. 24. ICC 2012 – E2NETS workshop OTTAWA – CANADA – JUNE 10-15 2012Agenda• Introduction• HW-SW platform• Power states• DPM issues and solutions• Experimental results 24/25 alessandro.bogliolo@uniurb.it
  25. 25. ICC 2012 – E2NETS workshop OTTAWA – CANADA – JUNE 10-15 2012Characterization results Data refer to a MSP430F2618 MCU powered at 3V and clocked at 16MHz 25/25 alessandro.bogliolo@uniurb.it
  26. 26. ICC 2012 – E2NETS workshop OTTAWA – CANADA – JUNE 10-15 2012Experimental results6.6mW Average power consumption of the MCU used to execute a periodic monitoring110uW task which keeps the CPU busy for 1s6.9uW Once Once per hour per day 26/25 alessandro.bogliolo@uniurb.it
  27. 27. ICC 2012 – E2NETS workshop OTTAWA – CANADA – JUNE 10-15 2012Conclusions• Ultra-low-power sensor node• Java-compatible virtual runtime environment• Power consumption ranging from 6.6mW to 0.1uW (in Hibernation)• Capable of reacting to external events and resume execution from any low-power state• All low-power modes directly exploitable from the Java runtime environment• Open-HW / Open-SW approach 27/25 alessandro.bogliolo@uniurb.it

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