1. Critical Design Review 24 February 2004 Weather Bulletin Board System (WeBBS): Fahid Jahrami, Arian Lalezari, Justin Lasiewicz, Joshua Miers, Nathan Seidle

2. Overview Approach –Block Diagrams –Division of Labor Specifications –Power –Wind Sensor –Microcontroller –Misc. Sensors –Communication –Enclosure/User Interface Schedule –Milestone I/II, Expo

3. Block Diagram: Power Assembly Sealed Solar Panel 8.5V 250mA in direct sunlight TPS62102 3.6V DC-DC Buck I q = 250µA TPS62102 5V DC-DC Buck I q = 250µA 6.7V LM317 Constant voltage charging of Lead Acid Chemistry 6V, 5Ah Battery Sealed Lead Acid 1A Automotive Fuse Protects against melt-down

4. Block Diagram: Sensor Platform DS18S20.5º C Precision Temperature I2C interface PIC 16F877A Flash memory based  C unit with boot loader MPX4115A Motorola Barometric Pressure - Analog Output HS1101 Relative Humidity Variable Capacitor 24LC256 32kB I2C EEPROM 3 Days of 5-Min Readings Cell Phone Data Cable UART control over incoming and outgoing data Serial LCD In-House 16x2 design 2.5V Precision Reference ±0.2% 2.5V Reference Detects absolute power levels Wind Sensor Solid State Ultrasonic PWM Output Power Consumption Monitors current usage throughout system Power Control Powers down circuit elements when not in use? 5V 50mA Burst 3.6V 400mA Burst

5. Division of Labor Power: –Fahid and Josh Communication and Enclosure: –WeBBS Wind Sensor: –Justin Microcontroller and misc. sensors: –Nate User Interface and Documentation: –Arian

6. Specifications: Power Distribution and Regulation Power Regulators –PQ20RX05 (I q = 4mA) –TPS62102?(I q = 250  A) Power Requirements –Sensors &  C: 4.4mA –Cell Phone: 8mA –Wind Sensor: 500  A –Regulators: 2×4mA –Total: 20.9mA

7. Specifications: Solar Cell Solar World part number SPE-225-6 –8.5V OC –250mA SC –2W –4 1 / 2 ” x 6 1 / 4 ”

8. Specifications: Battery Part Number BP4-6-T1 –Sealed Lead-Acid –6V, 5Ah Discharge Test –6V 4Ah (backup) battery –8.2  load (I = 732mA) –5.46hr expected life

9. Specifications: Battery Anticipated Usage –I avg = 20.9mA –t chg = 4.5hr –Calls: 4 × 2min

10. Specifications: Charging Circuit 1.Solar cell input, V in 2.On/off switch 3.V out. Note diode to prevent back flow from the battery, etc. 4.Set-voltage for the regulator to charge at 6.3 Volts 5.Ground

11. Specifications: Wind Sensor Parts –EFR-TSB40K5 –EFR-RSB40K5 Note –40kHz is within hearing range of some animals –Two 12.5  s chirps every 5 minutes

12. Specifications: Wind Sensor

13. Prototype Test –40kHz square wave V in –Falling-edge triggered Test Results –Noticeable change when blown on

14. Specifications: Microcontroller Parts –16F877A Software –Wake/Sleep on Command Interface –RS232 Data connection for programming and data acquisition

16. Specifications: Miscellaneous Sensors Parts –Temperature (I2C) –Dallas DS18B20 –Baro. Pressure (ADC) –Motorola MPX4115AP –Humidity (  = RC) –Humirel HS 1100 –Precipitation (TTL) –Pending Confirmation

17. Specifications: Communication Parts –Samsung A310, LG VX10, Sprint TP1100 –Embedded Socket Modem –Serial data cables Interface –AT command set –Used as modem at 14.4kbps –Power Interface Pending

18. Specifications: Enclosure Custom Plexiglas enclosure –Weatherproof –Transparent (for Expo) –Opaque (for installation) Dimensions (Projected) –10”×10” surface –5” height –Slanted 4 1 / 2 ” x 6 1 / 4 ” solar cell mount

19. Implementation: User Interface – Preliminary Data dump to Windows Application –Excel –Visual Basic Data dump to HyperTerminal –Test Scheme Prepared No on-station displays –Concern: Power

20. Implementation: User Interface – Projected Automatically updating web application On-station displays –LCD on box (backlight?)

21. Schedule

22. Milestone I: 16 March 2004 Power –Long-term field tests of charge and discharge with solar cell Wind Sensor –Calibration and enclosure finalized Microcontroller –Calibration of functional software implemented Miscellaneous Sensors –Calibration and testing finalized Communication –Prepare link to  C, home base for testing –Finalize modem tests Enclosure/UI –Begin preliminary enclosure –Finalize ghost and tests with simulated input

23. Milestone II: 6 April 2004 Power –Finalize tests, design –Begin final installation Wind Sensor –Finalized, calibrated, and installation begun Microcontroller –Testing of software completed –Installation begun Miscellaneous Sensors –Enclosure specifications finalized Communication –Tests and enclosure specifications finalized Enclosure/UI –Begin final enclosure construction –Test with field-generated input

24. Questions ?