1. Development of Sensor Board for 802.11 DPAC

2. BLOCK DIAGRAM Antenna DPAC WIFI MODULE UCSD Network RS 232 PC Output
Input
NEED 2 ANTENNAS
Humidity Temp
Sensor
SHT75
GPS
Lassen IQ
GSP Receiver
CO/NO2
Sensor
MiCS-4514
Solar
Radiation
Sensor
Li-200SA
Solar Panel
Current
Monitor
Battery
Voltage
Monitor

3. HARDWARE DESCRIPTION
The sensor board contains the hardware and firmware components required to implement a full Wi-Fi –compatible IEEE b network interface.
It concludes 4 main sections:
* The inputs
* DPAC
* The Outputs
* Power Supply

4. The Inputs The inputs are divided into two groups.
The group of the sensors include SHT75, MiCS 4514, GPS, Li200SA.
The group of power monitors include Solar panel current monitor, battery voltage monitor.

5. The Sensors These are the weather sensors
The sensor output signals includes two groups:
* Analog output (CO/NO2, Solar Radiation Sensor)
* Digital output (GPS, Humidity Temp SHT75 sensor)
These sensors connect with the board
via the connectors

6. SHT75 Sensor

9. Lassen iQ GSP receiver Module Mounting:
It uses a single 8-pin (2x4) male header connector (Samtec-ASP ) for both power and data I/O.
It is mounted on our sensor board by surface-Mount Mating Connector (Samtec- CLP ).
There are four mounting solder tabs on the bottom of the enclosure for securing it on the PCB.
Needs antenna

10. Cont.
RF Connector:
- The RF connector mounted on the Lassen iQ GPS receiver is a Hirose
Connector( H.FL-R-SMT (10) 50 Ohm).
GPS Antennas:
- The antenna receives the GPS satellite signals and passes them to the receiver. The GPS signals are spread spectrum signals in the 1575 MHz range and do not penetrate conductive or opaque surfaces.

11. Cont:
The Ultra-Compact Embedded GPS Antenna with an HFLconnector, is ideal for portable and mobile applications.

12. Cont. Power Requirements: -The Lassen iQ GPS module requires
+3.3 VDC ±0.3 VDC at 33 mA, typical excluding the antenna.
Battery Back-up:
-The Lassen iQ GPS receiver provides an input for battery back-up (BBU) from 2.5V to 3.6V power to keep the module's RAM memory alive and to power the real-time clock when the receiver's prime power is turned off.
- RAM memory is used to store the GPS almanac, ephemeris, and last position.

13. Cont.
Digital IO/Power Connector Pinout:

14. CO/NO2 Sensor (MiCS-4514)

15. Power and Measure Circuit in MiCS 4514

16. Sensor Characteristics

17. Li-Cor #LI-200SA Pyranometer
Measures total solar radiation
Measures direct and reflected solar radiation
mounts to tower with custom NRG side mounting boom and hose clamps
Sensor range from 0 to 3000W/m2

18. Output signal:
- small current signal proportional to total solar radiation (90 μA per 1000 Watts/m2)
- range from 0 μA to 270 μA (typical)
Measurement:
- Converts small current signal output into
differential ended voltage output by using Rload =100 Ohm
- Uses chip INA 122UA to convert into single ended Voltage to connet to DPAC
- With Rf=2.4KOhm,
- Chip Gain = 5+200k/2.4K=88.33.
- Voutmax= 270*10^-6*100*88.33 = 2.385V
SR Power =( Vout*10^6)/(9*88.33)

19. Solar Panel Current Monitor
Uses monitor current circuit via the voltage across an external sense resistor.
Chooses chip LTC6102 with analog Voltage output to connect with DPAC,
V offset= 10MicroV
R sense = 0.001Ohm, Rin=3 Ohm,
Rout = 2.49 K Ohm
I sense = Vout* Rout / (R sense*Rin)

20. Battery Voltage Monitor
Max DPAC analog input Voltage is 2.5V
Max Battery Voltage = 12V*1.2=14.4V.
Need to build Voltage divider for this input:
R1=18KOhm
R2=2KOhm
V-Bat
V Bat = 10*V in
V in
GND
DPAC

21. DPAC Airborne Module
Highly integrated b wireless module with radio, base-band & application processor
Built-in web server enables drop-in LAN and internet connectivity
Configurable serial, digital and analog I/O ports

22. DPAC Specifications Technology : . IEEE 802.11b DSSS, Wi-Fi compliant
Frequency:
– GHz (US/Can/Japan/Europe)
Modulation:
. DBPSK (1 Mbps), DQPSK (2 Mbps), and CCK (5.5 and 11 Mbps)
Clock Frequencies:
. 4.8 MHz – CPU reference clock
KHz – real-time clock
Channels
.USA/Canada: 11 channels (1 – 11)
Data Rate:
. 11, 5.5, 2, 1 Mbps (raw wireless rate)
MAC :
. CSMA/CA with ACK, RTS, CTS
RF Power:
. +15 dBm (typical) Approx.32 mW
Sensitivity:
. -82 dBm for 11 Mbps
.-86 dBm for 5.5 Mbps
.-88 dBm for 2 Mbps
.-90 dBm for 1 Mbps

23. Security WEP standard encryption, 64 or 128 bits
Antenna:
. Two U.FL coaxial connectors, 50Ω, supports receive diversity
Supply : 3.3 VDC
Current Consumption:
420 mA – transmit mode (typical)
350 mA – receive mode (typical)
250 mA – doze mode (typical – see Note 1 and Note 5 below)
235 mA – snooze mode (typical – see Note 1 and Note 5 below)
50 mA – sleep mode (typical – see Note 5 below)
Power Up Inrush Current 1900 mA (max)
Operating Temperature Industrial: -40°C − +85°C (see Note 2 below)
Application Processor 16-bit, MHz
Serial Interface
Memory:
Flash: 64 Kbytes onboard, 512 Kbytes expansion (see Note 4 below)
SRAM: 20 Kbytes onboard, 128 Kbytes expansion
Digital I/O Up to 8 digital I/O ports and status
Analog Inputs Up to 8 channels, 10-bit resolution, single ended, 0 – 2.5 V
Connector 36 pin (pn: HRS DF12-36DS-0.5 V) 4-mm height
802.11g also available

24. Pin Signal Assignments

25. The outputs There are two outputs for this board. It includes :
- External antenna:
DPAC Module has two U.Fl style connectors for connection to anntena.
These two connectors provide 50 Ohm impedance RF signals at 2.4GHz)
- RS 232 Connector:
DPAC Module has up to 512 KB Flash memory and 128 KB Static Random Acess Memory to support its function and features.

26. POWER SUPPLY R-Sense SP Current Monitor LTC6102 Solar Panel
+12V_SP
+12V_SP
Solar Panel
R-Sense
Unisolar Us-5 5W
12V Thin film Module
+5v DC to DC
Switch Converter
LM2673S-5.0
+12V
Charge Controller
+5V
Discharged
Battery
+12V_Batt
+12V
Charged
12V, 5 Ah -Battery
+3.3v DC to DC
Linear Converter
LP3962ES-3.3
Batt Voltage Monitor
Voltage Divider
+3.3V

27. Power Sources
The sensor board is powered from the 12V charge controller.
The 12V charge controller can derive power from either Unisolar Us-5 5W, 12V Thin film Module solar panel or 12V, 5 Ah -battery.
The charge controller will protect our batteries from being overcharged by our solar panels and it will block any reverse current as well.

28. Power Supplies
The sensor board is supplied power from +12V charge controller.
It derives its 5V and 3.3V supplies using onboard regulators
The 5 V power supply is based on an LM2673S-5.0 switching regulator.
The 3.3 V power supply is derived from the 5 V supply using a Series LDO (LP3962ES-3.3) regulator.
These two power supplies are used for DPAC and the sensor power.

29. Power Schematic
Power Schematic

30. DPAC SCHEMATIC
DPAC SCHEMATIC

31. SHT75 SCHEMATIC
SHT75 SCHEMATIC

32. Monitor Schematic
Monitor Schematic

33. GPS and LI200SA SCHEMATIC
GPS and LI200SA SCHEMATIC

34. RS232 and CO/NO2 Schematic
RS232 and CO/NO2 Schematic

35. PCB Layout
PCB Layout

36. Additional Board
The sensor board will be installed inside the box to protect it from the weather condition.
Outside board is designed and installed outside the box to mount some components that they can not be inside such as CO/NO2 sensor.
It includes MiCS 4514(CO/NO2) sensor, SMA, RS232 connector.

37. Outside Board Schematic

38. Outside board PCB