Detailed Design Review and Test Plan Project 7: Drifters

1. Detailed Design Review and Test PlanProject 7: Drifters Lance Ellerbe - BS EE Jamal Maduro - BS CpE Peter Rivera - BS ME Anthony Sabido - BS ME

2. Drifter Design Team

3. Project Overview • Develop a self-contained network of tracked surface drifters for near coastal application. • Housing • Electronics • Power System • GPS receiver • Radio transceiver • Microcontroller • Any of these drifters within range of the base station will then be able to send all the information from all other drifters, thus providing a self-contained drifter network.

4. Electrical Components • Microcontroller: • TI (Texas Instruments) MSP430G2553 microcontroller • Radio Transceiver • XBee-Pro XSC RF module’s • GPS module: • Maestro A2100 • Battery • Lithium ion • Temperature Sensor • Maxim DS18B20

5. Microcontroller, Radio Transceiver, and GPS Engineer: Jamal Maduro

6. QUICK REVIEW

7. Microcontroller

8. XBee Modes of Operation

9. XBee Data Verification Chain

10. GPS Diagram

11. Temperature Sensor Overview • Compared to the thermistor, the DS18B20 has memory and thus the temperature can be held until a more convenient time when the data can be logged. • Digital temperature sensor that uses serial communication through the DQ pin. • 1 temperature reading per GPS fix • Converts Temperature to 12-Bit Digital Word in 750ms (Max)

12. UPDATED SYSTEM

13. General Layout

14. System Flow Chart

15. Completed Tests 1. UART Test (Completed) A loop back circuit was made by connecting the microcontroller’s transmission pin to the receiving pin and then the following test programs located in the appendix were ran: • “UART_loop_9600baud.asm” – a continuous stream of data at a constant baud rate • “UART_echo_9600baud.asm” – real-time data input response at a constant baud rate

16. Completed Tests 2. SPI Test (Completed) A loop back circuit was made by connecting the microcontroller’s SOMI to the SIMO pin of another identical microcontroller (or loop back within one microcontroller), connecting and synchronizing, and their corresponding clock pins to one another. The output was viewed on a terminal emulator. • “SPI_UART.asm” – data passed in through UART transferred to SPI and outputted out of UART

17. Completed Tests 3. Timer Test – System wakeup simulation (Completed) The watchdog timer is configured to alternate two LEDs every 10 seconds and output a character via UART and SPI. Various time intervals were tested including the actual time that the tracking system will be asleep and active. • “Low_Power_Timer_Comm.asm” – data passed in through UART transferred to SPI and outputted out of UART transitioning out of low power mode.

18. Completed Tests 4. Sleep Mode Test (Completed) The microcontroller was connected to a digital multi-meter and the voltage level of all of its operation modes were recorded to ensure that the desired reduction in power consumption was achieved.

19. Completed Tests 5. XBee UART Communication (Completed) A circuit was made by connecting the microcontroller’s transmission pin to the receiving (Din) pin of the XBee and the output (Dout) from the XBee was connected to a RS-232 level shifter via a DB9 connection to a laptop computer and was observed on a terminal while running the test program located in the appendix: • “UART_cmd_57600baud.asm” – send binary commands to the XBee radio module

20. Completed Tests 6. XBee Firmware Test (Complete) Connect the XBee module to the RS-232 level shifter via a DB9 connection to a laptop computer and verify that the default settings are correctly initialized such that the default interface is binary command mode as opposed to AT command mode. Configure the desired settings if the default is incorrect and retest to ensure that firmware has been correctly updated and will not be reset upon loss of power.

21. Pending Tests 1. GPS SPI Communication (Pending...) A circuit will be made by connecting the microcontrollers SOMI pin to the SIMO pin of the GPS module, connecting and synchronizing their corresponding clock pins, and observing the data collected by the microcontroller in its RAM and/or registers.

22. Pending Tests 2. Temperature Sensor GPIO Communication (Pending...) A circuit will be made by connecting a GPIO on the microcontroller to the DQ pin of the digital temperature, different heat sources will be applied to the sensor and the output will be compared against a thermometer to ensure that the sensor is functioning correctly. The GPIO will be switched from input and output as needed.

23. Pending Tests 3. GPS Firmware Test (Pending...) Connect the GPS module to the RS-232 level shifter via a DB9 connection to a laptop computer and verify that the default settings are correctly initialized such that the only output is the NMEA RMC string. Configure the desired settings if the default is incorrect and retest to ensure that firmware has been correctly updated and will not be reset upon loss of power.

24. Pending Tests 4. Data Logging File System Test (Pending...) Connect the data logger (with the desired memory card inside) to the RS-232 level shifter via a DB9 connection to a laptop computer and verify that the file system is correctly configured. Test all immediately relevant operations such as reading, writing, and erasing data.

25. Pending Tests 5. Temperature Sensor Serial CommTest (Pending...) The temperature sensor will be tested in conjunction with the microcontroller. The timing limits of communication will be tested using the timer in the microcontroller to ensure that the suggested timing protocol in the datasheet will support correct functionality.

26. Antennas and Power Systems Engineer: Lance Ellerbe

27. Antennas

28. Radio Transceiver Antenna • The antenna has a operational frequency between 868MHz-928MHz. • This frequency range will allow the for the drifter to operate by relaying its position to nearby drifters via radio transmission on the 915MHz ISM (Industry, Scientific, Medical) band. • The antenna has a gain of 3.1 dB, doubling the signal strength (an output-to-input power ratio of 2:1) which translates into a gain of 3 dB which is the half power point.

29. Radio Transceiver Antenna Interfacing Radio Transceiver antenna • The radio transceiver antenna will be the implemented into the drifter system through the Xbee transceiver using a U.FL connector adaptor. This connector cable interfaces U.FL RF connectors to RP-SMA antennas.

30. GPS Antenna • SL1204 GeoHelix. • Active Antenna • Gain of +18 dB • Beam width of 135o .   • Operational voltage: 1.8-3.6V • Draws 3.4 mA max

31. GPS Antenna Interfacing GPS antenna • The Maestro A2100 also supports active antennas directly, by offering an antenna voltage feed pin (VANT – pin 15) • GPS module provides a maximum current draw of 50mA. • This active antenna should have a gain ≥ 15dB but the total gain should not exceed 30dB. • 50 Ω PCB strip line is required

32. Power Systems

33. Power Systems Overview • Low Power Consumption • Each must be able to operate on 3.3V maximum. • The drifter network will be designed to use the least amount of power when transmitting data. • The power supply will be selected in order to supply the adequate amount of amp-hours in order to provide enough current for each electrical component to be operational throughout its 15 day deployment.

34. Power Systems Current Component Selection : • Xbee • Operation Voltage: 3.0 -3.6VDC • Current Draw: • Transmitting current: 256mA • Receiving Current: 50 mA • Maestro A2100-A/B • Operation Voltage: 3.0V - 3.3VDC • Current Draw: • Peak Acquisition Current 45mA • Antennacurrent: 3.4 mA • Microcontroller • Operation Voltage: 1.8V - 3.6V • Active mode: 230uA • Standby Mode: 0.5uA •  Temperature Sensor • Current Draw: 1.5mA

35. Power Systems Voltage Regulator MAX882/MAX883/MAX884 line regulator • The regulator input supply voltage can range from 2.7V to 11.5V • Low Dropout Voltage: 220mV • Fixed Output voltages: 3.3V and 5V

36. Power Systems PCB protection • Lithium Ion batteries must connect to a protection circuit module to protect Li-Ion Battery from overcharge, over discharge  and to prevent accidental battery explosion due to its extra high energy density. Battery

37. Power Systems Current Component Selection PROGRESS: • Worst Case Scenario: 1 sec for each transmission/reception • 401.23 mA for 2.77 hours of ACTIVE operation • sleep mode considered negligible (uA range). • 401.23 mA × 2.77 hours = 1111.407 mAh • Battery needed would be something with 3.3 V and a capacity greater than 1111.407 mAh to adequately provide enough current to stay operational for a 15 day deployment.

38. Power Systems Battery • Ultrafire 18650 Protected Rechargeable Lithium Ion Battery • Nominal Voltage: 3.7V • Capacity: 3000mAh • The PCB protection that is needed for Lithium Ion batteries already integrated in the battery.

39. Power Systems Battery Configuration Parallel configuration would be ideal to increase the amount of Amp-Hours to supply the adequate amount of current to Microcontroller, GPS module, Radio Transceiver and Temperature Sensor for a 15 day period.

40. Power Systems • Power Systems Diagram Delivers 3.3V to the power supply pin of each component in the system

41. Power Systems Component Testing • The testing of this task will include a number of power consumption tests. First, each electrical component will be attached separately to a multimeter or oscilloscope to validate that the component is operating within its electrical specifications. • Second, based on the results in the previous step the results can be then used to tweak network parameters such as transmission time or microprocessor algorithms in an attempt to lower power consumption and increase theoretical operation time.

42. Power Systems Voltage Regulator Test The testing of this component in the power systems will test the different operation of the MAX884 linear regulator. • Using a multimeter we will input different values of input voltages(2.7V to 11.5V) and measure the current and voltage on the output pin. The results from this test will show how the effects of different voltages and currents on the input pin will change the output current on the output pin on the voltage regulator. • Test the different capabilities of the voltage regulator such as Shutdown Mode or Standby Mode. Based on this test we will see which Mode will be best to achieve the least amount of power consumption, but also allows the regulator to activate when needed.

43. Power Systems Battery test The testing of the battery includes testing the battery under a load similar to the drifter system to see how long the battery can last. • In this test we will connect the battery to a simulated load that draws approximately 400mA of current and test the battery over a certain amount of time. We would record the batteries beginning voltage and current, then record the voltage and current after the battery has been drained for a certain amount of time. This test would ensure that our drifter system will adequately be powered throughout a 15 day deployment.

44. Hull Design Engineers: Anthony Sabido and Peter Rivera

45. PROPOSED DESIGN Overview

46. 1 2 3 Major Features: Symmetric Semi-Circular Profile Fiberglass Hull Off-the-Shelf Deck Plate Low Cost Easy Fabrication Top Bowl Screw-in Deck Plate

47. Fiberglass • Low Density: • Cloth: 2.6 g/cm3 • Resin: 1.3 g/cm3 • Low Cost • 205-B Slow hardener (0.86qt.): $37.20 • 105-B Epoxy Resin (1 gal): $78.29

48. Sealing the Hull • 6” diameter deck-plate • Screw-in design • Made of Durable ABS plastic • O-ring for water tight seal • Low cost - $7.89

49. Proposed design Updated Hull

50. Mass Calculations