1. Energy Management in T2

2. [Energy_1]2 Motivation If the application must explicitly invoke power control operations, this will introduce application code complexity Let the OS automatically minimize energy consumption - Integrated Concurrency and Energy Management (ICEM)

3. ICEM (Integrated Concurrency and Energy Management) Most WSN OS are completely event-driven Diverse peripherals An application simply needs to make a set of asynchronous system calls and let OS schedule the underlying operations Power locks –When a client acquires a driver’s power lock: ICEM has powered and configured the hardware for the client –When a power lock is idle, ICEM powers down the underlying hardware

4. Example Implementations in T2 Lock Interface is named Resource in T2 Arbiter Configure Interface is named ResourceConfigure in T2 DefaultOwner Interface is named ResourceDefaultOwner in T2

5. Example Applications based on TelosB Every five minutes, the application samples four sensors (photo active, total solar, temperature, and humidity) and logs the readings in flash with a sequence number Every twelve hours, the application retrieves new readings from the flash and sends them to the gateway Five Operations –Sampe its four sensors –Log the record to flash

6. Motivation Example – Pseudocode for hand-tuned implementation without ICEM

7. TelosB

8. Five Operations Humidity and Temperature are digital sensors Total Solar and Photo Active are analog sensors The OS can concurrently sample one digital and one analog sensor The OS must arbitrate sensors of the same kind

9. also see TEP 108 at http://tinyos.cvs.sourceforge.net/*c heckout*/tinyos/tinyos- 2.x/doc/html/tep108.html 9 ICEM Drivers – Resource Arbitration Virtualized –Simplest for a client to use –Virtualized drivers buffer client requests –Provide implicit concurrency –Usually buffer functional requests (e.g. send a packet) Dedicated –Support a single user Shared –Provide explicit concurrency –Support multiple users, but users must contend for the driver through a lock –Usually buffer lock requests

10. ICME Drivers - Virtualized Oval: Client Example: –Data Link Packet Sender Round Robin policy –Application-level millisecond timers Maintain per-client state Schedule underlying hardware timer

11. Virtualized Example ADC (Analog-Digital-Converter) –A shared resource usually multiplexed between several clients –AdcReadClientC.nc, AdcReadNowClientC.nc and AdcReadStreamClientC.nc provide virtualized access to the HIL –AdcReadClientC.nc: tos/chips/msp430/adc12/AdcReadClientC.nc

12. ICME Drivers - Dedicated Low-level hardware resources Examples –GPIO Pins

13. ICME Drivers - Shared

14. CC2420 Stack

15. Arbiters Lock: Resource in T2 Arbiter Configure: ResourceConfigure DefaultOwner: ResourceDefaultOwn er

16. Atmegal 128 ADC

17. MTS300 Sensor Boards