Development of Sensor Board for 802.11 DPAC

Report
Development of
Sensor Board for
802.11 DPAC
BLOCK DIAGRAM

UCSD Network
RS 232
PC
Antenna
Output
DPAC WIFI
MODULE
Input
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
HARDWARE DESCRIPTION
 The sensor board contains the hardware
and firmware components required to
implement a full Wi-Fi –compatible IEEE
802.11b network interface.
 It concludes 4 main sections:
* The inputs
* DPAC
* The Outputs
* Power Supply
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.
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
SHT75 Sensor
Lassen iQ GSP receiver Module
Mounting:
 It uses a single 8-pin
(2x4) male header
connector (Samtec-ASP
69533-01) for both power
and data I/O.
 It is mounted on our
sensor board by surfaceMount Mating Connector
(Samtec- CLP-104-02).
 There are four mounting
solder tabs on the bottom
of the enclosure for
securing it on the PCB.
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.
Cont:
 The Ultra-Compact
Embedded GPS
Antenna with an
HFLconnector, is
ideal for portable and
mobile applications.
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.
Cont.
 Digital IO/Power Connector Pinout:
CO/NO2 Sensor (MiCS-4514)
Power and Measure Circuit in MiCS 4514
Sensor Characteristics
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
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)
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)
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:
V-Bat
R1=18KOhm
R2=2KOhm
V Bat = 10*V in
V in
GND
DPAC
DPAC Airborne Module
 Highly integrated 802.11b
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
DPAC Specifications
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Technology :
. IEEE 802.11b DSSS, Wi-Fi compliant
Frequency:
. 2.400 – 2.4835 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
. 32.768 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
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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, 120 MIPS @ 120 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
Pin Signal Assignments
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.
POWER SUPPLY
SP Current Monitor
LTC6102
+12V_SP
+12V_SP
R-Sense
Solar Panel
Unisolar Us-5 5W
12V Thin film Module
+12V
Charge Controller
Discharged
+5v DC to DC
Switch Converter
LM2673S-5.0
+5V
+12V_Batt
Battery
+12V
Charged
12V, 5 Ah -Battery
Batt Voltage Monitor
Voltage Divider
+3.3v DC to DC
Linear Converter
LP3962ES-3.3
+3.3V
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.
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.
 Power Schematic
Power Schematic
 DPAC SCHEMATIC
DPAC SCHEMATIC
 SHT75 SCHEMATIC
SHT75 SCHEMATIC
Monitor Schematic
 Monitor Schematic
GPS and LI200SA SCHEMATIC
 GPS and LI200SA SCHEMATIC
RS232 and CO/NO2 Schematic
 RS232 and CO/NO2 Schematic
PCB Layout
 PCB Layout
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.
Outside Board Schematic
 Outside Board Schematic
Outside board PCB

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