1. Low Power Sensor Node Design with MSP430 + CC2520 YoonMo Yeon 2008. 3. 26.

2. Contents Design Purpose CC2520DK Development Environment RF Test Current Consumption Test Further Works Hardware Software

3. Design Purpose Battery Powered Sensor Node Can last about 1-year End node only Low duty-cycle

4. Low Power Principles Use Interrupts to wake the processor and control program flow Peripherals should be switched on only when needed Minimize active duty cycle

5. Chip Selection CC2520 2.4GHz RF Transceiver Improvements over the CC2420 output power : 0dBm → +5dBm min. operating voltage : 2.1V → 1.8V low power modes (LPM1, LPM2) MSP430F2168 16bit low-power MCU

6. CC2520DK CC2520EM RF Module with antenna CCMSP-EM430F2618 MSP430F2618 core module 14-pin JTAG No additional IOs SmartRF05EB Provides various IOs & Power USB, RS-232, LCD, LED, Switch…

7. Development Environment Compiler IAR Embedded Workbench for MSP430 JTAG MSP430 USB-Debug-Interface

8. Example Code : PER Test BasicRF Simple protocol for Tx/Rx Not a complete data link or MAC layer Doesn’t have full error handling PER

9. PER Test Code (Tx.) Transmitter Sends 100 packets / sec. 10ms Timer Interrupt Enter LPM3 after sent one packet

10. Timer Configuration

12. halMcuSetLowPowerMode()

13. PER Test Code (Rx.) Receiver Wait until a packet is arrive Calculate PER & RSSI There is no LPMs

16. Outdoor RF Test The KNU campus 500m360m260m160m80m0

17. Test Result -4dBm mode power is too low to communicate At 500m distance, 10000 packets +0dBm mode : 357/1000 (35.7%) +4dBm mode : 47/1000 (4.7%) 76/1000(7.6%) Varys according to moving cars and so on…

18. Current Consumption Test Active Current MSP430F2618 (8MHz) : 4.7mA CC2520 : 1.6mA During Tx. loop in PER Test code Max. 41.5mA min. 3.94mA (LPM3) min. 8mA (No LPMs) CC2520 still remains active

19. Problems to be solved Sensors How to interface CC2520DK with sensors Design sensor circuit operating at 3.3V or Interfacing 3.3V circuit to 5V circuit Estimate active/stand-by current of sensors Z-Stack CC2520 Z-Stack is not developed yet (TIMAC 1.2.1 is available)

20. Further Works Study of MSP430 Architecture & Programming ZigBee Specification Related Works

21. References Texas instruments CC2420, CC2520 Datasheet CC2520 Development Kit User’s Guide (SWRU138) CC2520 Software Examples User’s Guide (SWRU137) MSP430x241x, MSP430x261x mixed signal microcontroller(SLAS541A) MSP430x2xx family users guide (SLAU144D) Google Earth KNU Campus image

22. Q & A

23. End of Presentation