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Runway Lighting – Team Golden Icarus
TI Design Contest
Final Report
ECE682
Team Members:
Matt Anker
Jeff Endicott
Clint Heiney
Foreword: In Greek mythology, Icarus had to escape danger by flying with wings made of wax and feathers
engineered by his Father. Although pre-warned to stay far away from the sun, young naive Icarus could not avoid
temptation which resulted in the failing of his wings and his demise. The Goal of TEAM GOLDEN ICARUS is to
harness the power of the sun and allow for the Safe landing of aircraft.
Executive Summary 1. Introduction
The project’s wireless system will provide a low cost effective lighting solution to
nocturnal take-off and landing of aircraft. This system will be portable and easily
implemented to new or existing areas, therefore covering a vast market.
2. Background
Design influences came from personal desires and hope to develop an easy implementation
of a complete system. At present time, there are very few other systems on the market
similar to the one that is designed in this report. The major benefit will provide an
inexpensive alternative to current runway lighting solutions
3.
Requirement Analysis and Specifications
The requirements for this system are based on current “wired” runway lighting of active
airfields. It should be able to be implemented quickly and with little effort to any plausible
area. Design specifications can be found in section 3, and Operational specifications our
shown below.
•
Pilot Controlled activation
•
Runtime of 5 minutes per cycle, with warning flash at 4.5 minutes
•
1 hour cumulative runtime operation
•
Dual intensity setting
•
3 mile visibility
4.
Project Design
To design and build at least two demonstrator samples for an innovative wireless runway
lighting system. The lights will exist as a system of 24 units for a 2,000ft runway, scalable
to 5,000ft runways or large helicopter landing zones. The constraints and requirements will
be evaluated to complete the design and construction. Once a solution has been solidified a
working model will be built. Then the units will field tested and analyzed to further study
any needed modifications.
i
5.
Statement of Work
Four Texas Instruments integrated circuits were chosen to be implemented into the circuit
design. The lighting unit circuit was completed with fabricated printed circuit boards.
Microcontroller code was developed to control the main lighting units through an MSP430
coupled with a CC2500 RFIC for radio control. Three proof-of-concept demonstrator units
using TI EZ430-RF2500 evaluation boards, two TPS6205x DC/DC converters, and a
TPS2052B power distribution switch have been constructed and are awaiting refinements in
the coding.
Additionally, a light-controlled unit using two Texas Instruments TPS6205x DC/DC
converters, a TLV3492 nano-power comparator, and a TPS2090D power distribution
switch was built and tested.
6.
Resources
The team consists of three well qualified individuals. The work will sectioned off toward
individual strengths. These team members all have skill to complete the given tasks, but a
collective force will be used in many areas of the design. Equipment for the project will be
obtained through TI and other resources will be utilized at The Ohio State University.
7.
Schedule and Costs
The design was broken into specific steps toward project completion. Development
hardware and software will be provided by TI so costs will only involve the construction of
the individual lighting units, which should approximately be $50/unit. Initial circuit
component costs are tabulated.
8.
Design Review Strategy
The design review will consist of in lab testing and review as well as field testing and
review. In the in lab testing each component was tested separately for functionality, and
then combined for a system level test. Tested components were then assembled on printed
circuit boards for field testing. Pending completion of field testing of a small batch of units,
the design will be scaled for small-scale production and tested on an airfield.
ii
Table of Contents List of Tables and Figures ............................................................................................................. iv
1. Introduction............................................................................................................................. 1
1-1. Purpose............................................................................................................................ 1
1-2. Problem Statement .......................................................................................................... 1
1-3. Scope............................................................................................................................... 1
2. Background ............................................................................................................................. 1
3. Requirement Analysis and Specifications .............................................................................. 2
4. Project Design......................................................................................................................... 2
4-1. System Design Overview................................................................................................ 2
4-2. Control unit ..................................................................................................................... 4
4-3. Lighting Unit................................................................................................................... 5
TI- TPS6205x.......................................................................................................................... 5
TI- TPS2052B......................................................................................................................... 6
TI- MSP430F2274 .................................................................................................................. 6
TI- CC2500 ............................................................................................................................. 6
4-4. Power Analysis, Lighting units....................................................................................... 7
4-5. Circuit operation and Coding.......................................................................................... 8
4-6. Physical Design............................................................................................................... 9
5. Statement of Work ................................................................................................................ 13
6. Resources .............................................................................................................................. 15
6-1. Personnel....................................................................................................................... 15
6-2. Facilities and Equipment............................................................................................... 15
7. Schedule and Costs ............................................................................................................... 16
7-1. Schedule History........................................................................................................... 16
7-2. Cost ............................................................................................................................... 17
8. Design Review Discussion ................................................................................................... 19
Appendix A:................................................................................................................................ A-1
Code ........................................................................................................................................ A-5
Master control unit.............................................................................................................. A-5
Lighting unit........................................................................................................................ A-6
Appendix B:................................................................................................................................ B-1
Light Level Controlled Runway Lighting Unit ...................................................................... B-1
System Design .................................................................................................................... B-1
TI- TPS6205x.................................................................................................................. B-1
TI- TPS2090D................................................................................................................. B-1
TI- TLV3492................................................................................................................... B-1
Power Analysis ................................................................................................................... B-2
Cost Analysis ...................................................................................................................... B-2
Performance Analysis ......................................................................................................... B-3
iii
List of Tables and Figures Figures
Figure 4.1.1: Control unit System Diagram……………………………………………………………………….3
Figure 4.1.2: Light Unit System Diagram………………………………………………………………………….4
Figure 4.2.1: Control Unit Schematic……………………………………………………………………………....5
Figure 4.3.1: Light Unit Schematic………………………………………………………………………………….7
Figure 4.6.1: Housing design of lighting units……………………………………………………………………10
Figure 4.6.2: Lighting Unit PCB Layout [RED-top layer, BLUE-bottom layer, GREEN-via]………..…...11
Figure 4.6.3: Completed Lighting Unit PCB…………………………………………………………………….12
Figure 4.6.4: Completed Lighting Unit, Side View………………………………………………………………12
Figure 4.6.5: Completed Lighting Unit with Solar Disc……………………………….………….…….………13
Figure A-1: Detailed Control unit schematic…………………………………………………………..………….A-1
Figure A-2: Detailed Lighting unit schematic………………………………………………………….………….A-2
Figure A-3: Flow chart for lighting unit code…………………………………………………………….……….A-3
Figure A-4: Detailed Physical dimensions and layout of housing………………………………….…………..A-4
Figure B-1: Light-Controlled Runway Light--System Schematic……………………………………………… .B-2
Figure B-2: Light-Controlled Lighting Unit Prototype…………………………………………………………..B-4
Figure B-3: Light-Controlled System Schematic (Full Size)……………………………………………………..B-5
Tables
Table 7.1.1: Labor Schedule………………………………………………………………….…………………….17
Table 7.2.1: Main circuit component costs…………………………………………….…………………………18
Table B-1: Light-Controlled Lighting Unit Bill of Materials
B-3
iv
1. Introduction
1-1. Purpose
At the end of the project period the team will have a complete design and
documentation along with a working prototype of a wireless runway lighting system.
1-2. Problem Statement
Most private general aviation airports do not have runway lighting. Therefore night
operations are nonexistent. The project’s wireless system will provide a low cost
effective lighting solution to nocturnal take-off and landing of aircrafts. This system
will be portable and easily implemented to new or existing areas, therefore covering a
vast market.
1-3. Scope
The project will develop working units to be integrated into a wireless runway lighting
system. Final circuit analysis and troubleshooting should result in these units. Upon
completion of the TI contest, units will be able to be streamlined and assembled with
the given board design, and complete systems can then be marketed.
2. Background
At present time, there are very few other systems on the market similar to the one that is
designed in this report. One known existing system, Model A704-5 by Flight Light Inc1, is
much more robust and expensive. The lighting system in this report is designed to be much
cheaper and used for smaller applications. The Model A704-5 has many more features to
make it applicable for military applications as well as larger scale air landing strips. The
one being proposed is meant for smaller applications where basic lighting is needed.
Design influences came from personal desires and hope to develop an easy
implementation of a complete system. The major benefit will provide an inexpensive
alternative to current runway lighting solutions. Further more the units will be capable of
remote location due to the wireless and use of alternative energy source.
1
Model A704-5 by Flight Light Inc.: http://www.flightlight.com/airportlighting/6.5.1/6.5.1.html
1
3. Requirement Analysis and Specifications
The wireless lighting system has to meet selected parameters to be practical. It should
function in the same way as current “wired” systems used in the active airfields today. A
list of operational and design specifications are shown below.
Operational
•
Pilot Controlled activation
•
Runtime of 5 minutes per cycle, with warning flash at 4.5 minutes
•
1 hour cumulative runtime operation
•
Dual intensity setting
•
3 mile visibility
Design
•
•
•
•
•
•
•
Alternative power source
Low Cost materials
Minimal maintenance
System must be portable
Wireless unit control
Weather-resistant
Operational temperature -20 to 50 degree Celsius
4. Project Design
The following sections will explain the complete project design. Starting with an
overview and then detailed sections of the function and workings of individual
components.
4-1. System Design Overview
The runway lighting system hardware is comprised of two different components; the
lighting units and a master control unit. In a typical installation, the lighting units will
be distributed at intervals of 200 feet along the edges of an airport runway. The number
of lighting units will vary with the length of the airfield to be lit and/or the desired
coverage. The system will require a single control unit typically located inside or
mounted externally on a structure such as a hangar where AC power is available.
Antennas will be mounted externally from the control unit to ensure optimal radio
operation.
The purpose of the master control unit is to receive signals in the form of noise
pulses from the radio transmitter of the aircraft controlling the runway lighting system
and translate those into commands usable by the 2.4 GHz command network. The
Hamtronics R122 air band receiver will receive the command signal from the aircraft
2
and pass that to a MSP430 microcontroller for interpretation. The MSP430 will then
instruct the CC2500 2.4GHz radio frequency transceiver to transmit a digital signal
indicating a desired level of illumination. The block diagram for the conceptual MCU
design is shown in Figure 4.1.1 below.
Figure 4.1.1: Control unit System Diagram
The purpose of the lighting unit is primarily to illuminate the outline of a runway in
order to aid a pilot in aligning the aircraft for takeoff or landing. The lighting units will
accomplish this by gathering sunlight through a photovoltaic array during the day and
storing that energy for use at night. Energy is to be stored in a single Lithium-Ion cell
with a nominal voltage of 3.7V, and requiring a charge voltage of 4.2V. The lighting
unit is to receive a 2.4 GHz digital command signal through a CC2500 RF transceiver
which is then passed to the MSP430 microcontroller. The MSP430 is then to activate a
MOSFET switch IC which will power the LED array. The MSP430 will then command
the CC2500 to retransmit the command signal to nearby lighting units as a daisy chain
network. The microcontroller must then start a timer to shut down the LED array after a
fixed amount of time expires. Finally, the microcontroller must strobe the LED array as
a pre-shutdown warning just prior to runtime expiration. The conceptual block diagram
of the lighting unit is shown in Figure 4.1.2 below.
3
Figure 4.1.2: Light Unit System Diagram
4-2. Control unit
The control unit is comprised of two primary components, a MSP430F2274
microcontroller coupled with a CC2500. Ancillary components include a UA78M33C
3.3V linear voltage regulator and two opto-isolators. The control unit is to interface with
a Hamtronics R122 air band receiver via a four pin header on the control unit printed
circuit board. The R122 uses current sinking bipolar transistor outputs and it is powered
by a 12V power supply. Therefore a pair of opto-isolators will be used to interface the
R122 to the MSP430 microcontroller’s 3.3V logic levels. A logic low input on the
MSP430 will cause the control unit to execute its program code and transmit control
signals. The MSP430 writes to the CC2500 RF transceiver, whose RF output is matched
to an externally mounted 50 Ohm antenna through a lumped element balun. The CC2500
will transmit blindly for a preprogrammed duration of 5 seconds on the 2.4 GHz
unlicensed band and is expected to have a range of 400 feet with a standard omnidirectional antenna. The control unit schematic is shown in Figure 4.2.1 below and is
reprinted in Appendix.
4
+12VDC Supply
ANTENNA 2.4GHz 50 Ohm
R122 E4
HAMTRONICS R122
VHF AIR BAND RECEIVER R122 E5
1
2
1
2
3
4
SMA
R122 E6
GROUND
+12V
IN
C9
33 uF
Vcc
OUT
COM
C8
10 uF
UA78M33C
R6
47 K
MSP430F2274IDA
2
3
R7
150
8
9
5
1
R8
150
ISO1
4
4
ISO2
2
16
5
1
1
2
3
4
2
10
J1
PROGRAMMING
HEADER
6
5
4
3
2
1
R4
47 K
17
18
19
20
21
25
7
1
26
4
15
DVCC
P2.5/ROSC
P2.0/ACLK/A0/OA0I0
P2.1/TAINCLK/SMCLK/A1/OA0O
P2.2/TA0/A2/OA0I1
AVCC
P4.0/TB0
P4.1/TB1
P4.2/TB2
P4.3/TB0/A12
P4.4/TB1A13
P3.4/UCA0TXD/UCA0SIMO
RST*/NMI/SBWTDIO
TEST/SBWTCK
P3.5/UCA0RXD/UCA0SOMI
DVSS
AVSS
XIN/P2.6
XOUT/P2.7
P3.0/UCB0STE/UCA0CLK/A5
P3.1/UCB0SIMO/UCB0SDA
P3.2/UCB01SOMI/UCB0SCL
P3.3/UCB0CLK/UCA0STE
P1.7/TA2/TDO/TDI
P1.6/TA1/TDI/TCLK
P1.5/TA0/TMS
P1.4/SMCLK/TCK
P1.3/TA2
P1.2/TA1
P1.1/TA0
P1.0/TACLK/ADC10CLK
P2.4/TA2/A4/VREF+/VeREF+/OA1I0
P2.3/TA1/A3/VREF-/VeREF-/OA1I1/OA1O
P3.7/A7
P3.6/A6
P4.7/TBCLK
P4.6/TBOUTHA15
P4.5/TB2A14
CC2500
6
5
11
12
13
14
38
37
36
35
34
33
32
31
30
29
28
27
24
23
22
3
6
7
20
2
1
GDO2
GDO0(ATEST)
CSn
SI
SO(GDO1)
SCLK
DVDD
AVDD
AVDD
AVDD
AVDD
DGUARD
RF_N
RF_P
R_BIAS
5
C7
10 nF
4
9
11
14
15
18
220 pF
C18
C17
C10
C16 100 pF
13
12
L1
1.2 nH C12
1.0 pF
L3
C11 100 pF
L2
R3
56 K
DCOUPL
C13
1.0 pF
1
C14
1.8 pF
26.0 MHz
C5
27 pF
8
10
XOSC_Q1
XOSC_Q2
GND
GND
J3
SMA
1.2 nH
1.2 nH
17
16
19
C6
27 pF
CONN PCB 6-R
Figure 4.2.1: Control Unit Schematic
4-3. Lighting Unit
The lighting unit is required to capture solar energy, store that energy for later use,
receive a RF signal to activate its lighting array, and transmit a signal to other lighting
units to activate their lighting arrays and retransmit the control signal. With all these
requirements, the lighting units are significantly more complex than the master control
unit. The lighting unit gathers solar energy using a series pair of PowerFilm MP3-37
thin film photovoltaic cells, each rated at 3V nominal at a maximum current of 50mA.
The photovoltaic cells are connected in series and their 6 Volts are applied to the
input of a TPS62050DGS adjustable output synchronous step-down converter.
TI- TPS6205x
The TPS62050 is a high-efficiency inductive buck converter using PWM control
and integrated N- and P-channel power MOSFET switches all in one small package.
The adjustable TPS62050 requires an external feedback loop using a voltage divider
circuit, an external power inductor, and two ripple-rejection capacitors.
The converter is set to 4.5V and is connected to the lithium-ion cell through an
external Schottky diode having a voltage drop of 0.3V. This results in a regulated
charge voltage of 4.2V to the Tenergy T18650 lithium-ion cell having a nominal
voltage of 3.7V and capacity of 2200mAh.
The lithium-ion cell supplies a TPS62056DGS fixed output synchronous stepdown converter set at 3.3V. The TPS62056 has identical specifications to the
TPS62050, and requires only an external feedback loop, a power inductor, and two
5
C15
1.5 pF
2
R5
47 K
ripple-rejection capacitors. The filtering capacitor on the output side of the 3.3V
regulator requires a value of 100μF to ensure ripple-free power to the logic circuitry.
The lighting array uses twelve white light emitting diodes mounted in two groups
of 4 and 8 LEDs to enable various lighting levels. The LED array is controlled by a
TPS2052B current limited power distribution switch drawing unregulated power
directly from the Li-Ion cell.
TI- TPS2052B
The TPS2052B is a dual channel switch using a pair of 70 mΩ N-channel
MOSFET power switches whose gates are driven by an internal charge pump resulting
in complete isolation between the control side and the power side of the IC. The
TPS2052B is current limited to 500mA and has an undervoltage lockout at 2.7V which
will prevent damage to the Li-Ion cell from excessive discharge.
TI- MSP430F2274
A MSP430F2274 microcontroller is used to control the lighting unit. The
MSP430 is a low power device with a 16-bit RISC CPU, 32KB of non-volatile flash
memory, and 1KB of RAM. The microcontroller is powered from the Vcc bus off of
the TPS62056 3.3V power converter. The MSP430 is interfaced with the TPS2052B
power distribution switch and the CC2500 RF transceiver.
TI- CC2500
The CC2500 is a 2.4 GHz radio frequency transceiver integrated with a
configurable baseband modem. The CC2500 is a low-power device that can polled at
low duty cycles to save power due to its fast startup time. The CC2500 uses a 26 MHz
crystal oscillator for a frequency reference. A simple microstrip folded dipole antenna
with 7.4 dB of gain is used with the CC2500 transceiver.
The complete light unit schematic is shown in Figure 4.3.1 below and in
Appendix A.
6
7
FB
LBI
PG
SY NC
LBO
GND
PGND
MP3-37
3V / 50mA
L1
10 uH
U4
TPS62056DGS
D1
9
1
1PS76SB10
5
R1
768 K
C2
7.0 pF
8
6
C3
22 uF
2
SW
EN
FB
L2
10 uH
Vcc
9
5
U5
TPS2052BDR
T18650 Li-Ion
3.7V
4
VIN
C11
10 uF
R2
93.1 K
7
LBI
PG
SY NC
LBO
GND
PGND
3
6
C1
10 uF
SW
EN
3
MP3-37
3V / 50mA
VIN
10
8
10
U3
TPS62050DGS
1
4
C4
100 uF
LED1
LED2
2
2
3
4
1
IN
OC1
EN1 OUT1
EN2 OUT2
GND OC2
8
7
6
5
SLX-LX5093UWC/C
Vcc
U1
U2
MSP430F2274IDA
2
3
8
9
10
16
R4
47.5 K
H1
PROGRAMMING
HEADER
6
5
4
3
2
1
17
18
19
20
21
25
7
1
26
4
15
DVCC
P2.5/ROSC
P2.0/ACLK/A0/OA0I0
P2.1/TAINCLK/SMCLK/A1/OA0O
P2.2/TA0/A2/OA0I1
AVCC
P4.0/TB0
P4.1/TB1
P4.2/TB2
P4.3/TB0/A12
P4.4/TB1A13
P3.4/UCA0TXD/UCA0SIMO
RST*/NMI/SBWTDIO
TEST/SBWTCK
P3.5/UCA0RXD/UCA0SOMI
DVSS
AVSS
XIN/P2.6
XOUT/P2.7
P3.0/UCB0STE/UCA0CLK/A5
P3.1/UCB0SIMO/UCB0SDA
P3.2/UCB01SOMI/UCB0SCL
P3.3/UCB0CLK/UCA0STE
P1.7/TA2/TDO/TDI
P1.6/TA1/TDI/TCLK
P1.5/TA0/TMS
P1.4/SMCLK/TCK
P1.3/TA2
P1.2/TA1
P1.1/TA0
P1.0/TACLK/ADC10CLK
P2.4/TA2/A4/VREF+/VeREF+/OA1I0
P2.3/TA1/A3/VREF-/VeREF-/OA1I1/OA1O
P3.7/A7
P3.6/A6
P4.7/TBCLK
P4.6/TBOUTHA15
P4.5/TB2A14
CC2500
6
5
11
12
13
14
38
37
36
35
34
33
32
31
30
29
28
27
24
23
22
3
6
7
20
2
1
GDO2
GDO0(ATEST)
CSn
SI
SO(GDO1)
SCLK
DVDD
AVDD
AVDD
AVDD
AVDD
DGUARD
RF_N
RF_P
R_BIAS
5
C7
10 nF
LED2
LED1
C5
27 pF
X1
26.0 MHz
8
10
4
9
11
14
15
18
C9
C10
13
12
17
R3
56 K
DCOUPL
XOSC_Q1
XOSC_Q2
C8 220 pF
GND
GND
16
19
C6
27 pF
Figure 4.3.1: Light Unit Schematic
4-4. Power Analysis, Lighting units
The lighting units must be built to operate independently of external power sources, and
will be deployed on an airfield with varying solar exposure and weather conditions.
With this requirement in mind, the lighting unit must be able to collect more energy
than would be needed for operation according to the requirements analysis such that
energy could be stored for future use. Solar energy is captured with the PowerFilm
Solar MP3-37 thin film photovoltaic cells wired in a series configuration that will
provide 6V and 50mA with direct solar exposure. Assuming 12 hours of daylight with
4 hours of direct exposure and 8 hours of indirect exposure, the amount of energy
captured can be calculated as follows:
E total = ∑ E DIRECT + E INDIRECT = 4(50mA) + 8(25mA) = 400mAh
Using a TPS62050 inductive buck-converter and assuming an efficiency of 92% as
predicted by the converter’s datasheet, the amount of energy delivered to the battery is
approximately 368mAh.
A potential concern with using a Lithium-Ion cell is to protect the cell from both
over- and under-charging. The manufacturer’s datasheet on the Tenergy T18650 3.7V
2,200mAh lithium-ion cell instruct that charging should be done under a constant
voltage of 4.2V and current limited. The TPS62050 delivers 4.2V to the battery after
subtracting the forward voltage of the Schottky diode used for reverse current flow
protection. Under testing with a bench power supply, the current delivered to the cell
would decrease to micro-amp levels as the cell voltage reached 4.2V. With
photovoltaic cells supplying the power converter, the maximum current that could be
delivered to the cells is only 50mA. Overcharging is therefore not considered an issue.
Undercharge protection is contained within the TPS62056 power converter supplying
7
power to the logic circuitry. When the battery voltage drops below 2.7V, this exceeds
the dropout voltage of the logic power converter and load is removed from the cell.
The LED array requires 120mA of current with all the lights on as measured. If
the runway lights were required to be lit for a total of one hour, then only 120mAh of
the Li-Ion battery’s 2,200mAh capacity is to be used for lighting.
The control circuitry including the MSP430 microcontroller and the CC2500
radio transceiver will be operated such that the CC2500 polls once every second then
shuts down if no packet is received. The CC2500 requires 8.1μA in this configuration,
and the MSP430 requires 270μA in active mode. Assuming that the pair use an average
of 280μA when in standby (defined as polling the radio every second waiting for a
command signal), the energy required is only approximately 7mAh per day. The
energy requirements of the control circuitry are insignificant compared to the amount of
energy captured. The lighting unit can therefore remain in standby for weeks without
significant sunlight before the battery is depleted.
4-5.Circuit operation and Coding
As mentioned earlier control of each lighting unit will be accomplished by integrating a
Texas Instruments MSP430 microcontroller and a Texas Instruments-Chipcon CC2500
RF transceiver into each unit. The lighting units will be pilot activated using a
Hamtronics R122 Aircraft Band Receiver2 interfaced with another MSP430 and
CC2500 in a master control cabinet. The R122 will receive the aircraft’s signal as a
series of microphone clicks over a given period of time and activate one of three outputs
to set intensity levels. These outputs will be connected to input ports on the MSP430
microcontroller which will then interpret the selected lighting intensity and send that
code to the RF transceiver which will repeat the transmission for a set period of time
expected to be 1 to 3 seconds. The nearest lighting units will receive the transmission
from the master controller and will then pull their microcontrollers out of low power
mode by means of an interrupt. The microcontroller will read the intensity code,
activate the appropriate LED array, and start its internal clock for 5 minute activation
(with shutdown warning flashes to begin at 4 minutes 30 seconds elapsed time). The
microcontroller then sends a command to the RF transceiver chip to transmit the
activation code for 1 second. At this point, the microcontroller will be set to ignore
further signals from the RF transceiver for a period of 30 seconds as the control signals
propagate down the length of the runway. As the maximum range of an individual
transmission will only need to be 250 ft, RF power levels and consequently power
consumption will be kept at a minimum. The short range of transmission will also
allow the requisite RF antenna(s) to be fabricated using inexpensive microstrip
techniques built onto the main printed circuit board rather than requiring an external
whip antenna. The actual code of this operation is attached in Appendix A along with a
flow chart in Figure A-3.
2
Hamtronics R122 Airband Receiver: http://www.hamtronics.com/r122.htm
8
4-6. Physical Design
The lighting unit is intended to be housed inside inexpensive materials such as PVC
pipe, and as such is a circular design of 3.25” diameter. The LED lighting array is to be
mounted on a set of four riser boards pointed outward at a slight upward angle.
The housing for these units is designed using existing off-the-shelf materials that
will be both inexpensive and simple to fabricate. Durability is also an important
consideration because the housings will be left in the elements for their entire design
lifespan; therefore, the materials chosen must operate under a wide temperature range.
The housing will be fabricated out of polyvinyl chloride (PVC) and the lamp lens will
be fabricated from cast acrylic. The PVC housing consists of three components, a
ground stake made of 3/4” (nominal) schedule-40 water pipe, a body consisting of a 3”
(nominal) drain pipe cap, and a solar disc made of 1/16” PVC sheet stock. The ground
stake and body are to be bonded with PVC cement, as are the body and solar disc. The
lamp lens assembly is to be fabricated from 3” ID cast acrylic tubing with a wall
thickness of 1/8” bonded with IPS Weld-On #4 acrylic cement to a top cap of 1/8” cast
acrylic sheet stock. The lens assembly is then bonded to the solar disc/body tube
assembly, and upward facing joints will be caulked with silicone adhesive. After the
solar cells are bonded to the solar disc and electrical connections established, the cells
will be laminated with sheet of 0.060” cast acrylic to protect them from weather effects.
Finally, the lens and solar cells are to be masked off, and the entire assembly painted
with industrial grade fluorescent marking enamel, standard orange hazard color. The
design utilizes inexpensive existing materials which can be easily hand assembled on a
small scale, but could also be scaled-up to mass production using purpose-built molds.
9
Figure 4.6.1: Housing design of lighting units.
The printed circuit board was designed in EAGLE 4.13 as a two layer all-surfacemount PCB. All traces were hand routed with 10 mil widths for data traces and 24-32
mil widths for power traces. All vias used a 20 mil diameter. The entire bottom layer,
except for several interconnect traces, is ground plane. IC pads used include a DA38
TSSOP SMT package used for the MSP430F2274IDA, a QLP20 quad leadless package
used for the CC2500, MSOP10 SMT package used for the TPS6205x power converters,
and the SOIC8 used with the TPS2052 power switch. With the exception of the
MSOP10, the packages were available in the EAGLE libraries. The RF transceiver uses
a folded dipole antenna fabricated from microstrip traces according to Texas
Instruments design note DN004 on the CC25xx family of RF transceivers. The bottom
ground plane is absent below the microstrip antenna. Silkscreen component labeling
was added to the top layer of the board for ease of assembly. The single lighting unit
PCB was then copied and tiled in the EAGLE editor to fill a 12x12” PCB blank for
most economical production. The PCB layout is shown in Figure 4.6.2 below.
10
Figure 4.6.2: Lighting Unit PCB Layout [RED-top layer, BLUE-bottom layer, GREEN-via]
The PCBs were fabricated using the Quick-turn Q2 service from Sunstone
Circuits. This process creates a .062” 1-oz copper FR4 printed circuit board in a
photolithography process. The board may be up to two layers, has tinned pads, plated
through-holes/vias, soldermask layer on both sides, and silkscreen on the top layer. The
individual lighting units are then separated from the 12x12” production board with a
scroll saw.
Assembly of the prototype lighting units is performed by hand using a hot air
process for all surface mount ICs and discrete components smaller than 0603 packages.
Solder paste was applied to the pads on the PCB for the device to be mounted, and then
the larger packages were held in place with Kapton tape or smaller components with
fine tweezers. Hot air was applied from a Xytronic HAP-60 hot air pencil to reflow the
solder paste, and then bond the components once reflow was complete and the air
11
temperature ramped up. Visual and electrical inspection of all solder joints is
performed after the component is in place. Components such as power supply
capacitors and inductors were soldered in place with a temperature regulated pencil tip
iron from a Xytonic 988-D rework station. A completed lighting unit PCB is shown in
Figures 4.6.3 and 4.6.4 below. The semi-completed lighting unit is shown with the
solar disc attached for charging tests in Figure 4.6.5.
Figure 4.6.3: Completed Lighting Unit PCB
Figure 4.6.4: Completed Lighting Unit, Side View
12
Figure 4.6.5: Completed Lighting Unit with Solar Disc
5. Statement of Work Initial power supply testing was conducted using a pair of Texas Instruments
TPS62050EVM power converter evaluation modules, neither of which was functional
upon arrival. All extraneous passive components were removed from the EVM boards
such that the design matched the published TI reference circuit. Both power converter
ICs were replaced using a hot air rework process, with one of the converters changed to a
TPS62056 fixed voltage power converter. The TPS62050 was set to output a voltage of
4.2V, and a series pair of MP3-37 photovoltaic cells connected to the input terminals.
With direct sunlight, the charging system was capable of delivering 4.2V at 50mA as
rated. Connecting the output of the power converter EVM to the Li-Ion battery, the
charging system was capable of delivering 50mA to the battery when the cell voltage was
3.6V. When the solar lighting levels dropped to twilight levels, a reverse flow of just less
than 5mA was observed. In order to prevent power losses from reverse flow and to
protect the power converter and photovoltaic cells from damage, a Schottky diode with a
forward voltage of 0.35V was installed on the output of the power converter. Increasing
the output voltage of the converter to 4.5V rendered the same performance as before.
With the power converter circuitry installed on the prototype circuit boards, the
battery charging converter performed just as did the evaluation module. The 3.3V logic
circuitry regulator, the TPS62056 showed a measured output voltage of 1.56V and the
output waveform showed a significant amount of ripple with the average level at 1.56 as
measured. A 10μF capacitor was applied across the power input rail and output levels
13
were then 3.3V as rated. A significant amount of power supply noise and ripple could be
observed on an oscilloscope, and this noise was overwhelming the signal from the crystal
oscillator on the CC2500 transceiver. The anti-ripple capacitor size was increased from
the 22μF value suggested in the TI reference design to a 100μF electrolytic. This
removed all remaining ripple and a clean clock waveform could be observed from the
crystal oscillator.
Once the power supply noise had been remedied and a clean clock signal
appearing on the oscillator terminals, it was expected that the CC2500 would then be able
to transmit and receive using the TI distributed temperature sensor sample code. When
the CC2500 is transmitting, a slight spike can be observed on the otherwise DC
waveform seen on the antenna terminals. The CC2500 is not functioning because of
either of the following: incorrectly sized power supply decoupling capacitors or thermal
damage to the IC during installation. The device datasheet mentions IPC/JEDEC J-STD020D soldering standard, which must be purchased. Excerpts of the standard mention a
maximum reflow temperature of 235°C which is lower than the minimum available
temperature on the hot air pencil. Attempting to solder the devices using minimum
temperature settings on the hot air pencil failed to melt the solder paste as the circuit
traces were acting as a heat sink. In order to successfully solder the CC2500 RF IC to the
fabricated circuit boards a reflow oven will be necessary. Otherwise the fabrication will
have to be contracted out to a prototyping facility with the proper equipment.
The MSP430 is fully functional as the microcontroller can be programmed by a
computer, and its outputs can be controlled from the debug interface. Activating the
lighting arrays through ports P3.3 and P3.4 on the MSP430, the logic high output levels
do turn on the LED array through the TPS2052 NMOS power switch.
In order to complete testing of the proof of concept units, three circuit boards
were assembled with power converters and the TPS2052 power control IC installed. An
EZ430-RF2500 evaluation module was then wired to the completed power supplies. The
boards were installed in a completed housing. With this configuration, the lights can be
controlled through the debug interface of the MSP430, and the microcontroller/RF
combination runs the TI distributed temperature sensor code and communicates with an
access point. However, completion of a purpose specific code based on peer-to-peer
signaling has been significantly delayed by the lack of documentation on coding using
the SIMPLICI-TI networking protocol, particularly in a p2p configuration. Further
testing of the radio controlled system will be completed if better code documentation
becomes available.
An analog version of the runway lighting unit that senses light levels and battery
voltages to control light activation requiring only minor modifications to the lighting unit
PCBs was constructed and is fully described in Appendix B.
14
6. Resources 6-1. Personnel
This project involves three Electrical Engineering students; Matthew Anker, Clint
Heiney, and Jeffery Endicott. Each has 4 years in the Ohio State University Engineering
program. They are all preparing to graduate with degrees in electrical engineering.
Matthew Anker has an extensive background in general aviation as an instrument
rated private pilot flying Cherokee's off of a private grass airfield. Electrical engineering
experience includes coursework in electromagnetics, microwave circuits, and
analog/mixed signal circuitry. Matt has run an audio electronics modification firm,
SACDmods.com, for 6 years and has experience and equipment for fabrication of the
design.
Clint Heiney’s background is imbedded in power system analysis and electric
machines. Other skills that will benefit this project are experience with lab work on
microprocessor and digital logic. Project history includes a Microwave circuit where he
gained extensive knowledge on the benefits of utilizing Matlab for design purposes.
Jeff Endicott has taken the Resolve class series, ECE 561, and ECE 662. The
resolve series studies good programming practices. ECE 561 is a class in the use and
design of basic computer chips. ECE 662 studies the design and operation of
microprocessors. Also taken an internship with JDSU where he studied VoIP and IMS.
6-2. Facilities and Equipment
The University will provide meeting area as well as resources to buy most of the parts
to make a prototype of the system. Labs with ample computers and internet access will
be utilized in any/some testing. The following items will be needed to construct and test
the working prototypes. Further details on testing equipment and facilities are listed
here.
1. Matt Anker’s SACDmods mobile shop:
• Test Equipment:
a) Tektronix 7904 500MHz analog oscilloscope
b) Fluke 73-III auto-ranging digital multimeter
c) BK Precision 875B LCR meter
• Fabrication Equipment:
a) Xytronic 988D digital soldering station
HAP-60 hot air pencil
b) Delta SM600 scroll saw
• Programmer:
15
a) TI EZ430-RF2500 Development Tool modified with .100” plug
b) Dell Inspiron 1000 with Windows XP Pro
2. Caldwell Laboratory, Room 239
• Used primarily as a meeting room, and design discussion with the
professor and assistant.
7. Schedule and Costs 7-1. Schedule History
The division of labor over the 9 week design is shown in Table 7.1.1 on the following
page.
16
7-2. Cost
Preliminary costs of the main circuit components are shown below in Table 7.2.1.
Housing and final costs will be calculated upon completion.
17
Table 7.2.1: Main circuit component costs.
Part Ref.
Mfg. Part #
Description
DK P/N
Unit Price
U1
MSP430F2274IDAR
IC MCU 16BIT 32K FLASH 38-TSSOP
296-21439-1-ND
$5.3600
U2
CC2500RTKR
IC RF TXRX SNGL-CHIP LP 20-QFN
296-19586-1-ND
$2.7000
U3
TPS62050DGSR
IC STEP-DOWN CONV HI-EFF 10-MSOP
296-14392-1-ND
$3.3300
U4
TPS62056DGSR
IC STEP-DOWN CONV HI-EFF 10-MSOP
296-14212-5-ND
$3.3300
U5
TPS2052BDR
IC POWER DIST SWITCH DUAL 8-SOIC
296-17451-1-ND
$1.1000
L1
SLF7032T-100M1R4-2-PF
INDUCTOR SHIELD PWR 10UH 7032
445-1998-1-ND
$0.9650
L2
SLF7032T-100M1R4-2-PF
INDUCTOR SHIELD PWR 10UH 7032
445-1998-1-ND
$0.9650
X1
NX3225SA-26.000000MHZ
CRYSTAL 26.000000 MHZ SMD 8PF
644-1054-1-ND
$0.6130
H1
22-28-4060
CONN HEADER 6POS .100 VERT TIN
WM6406-ND
$0.4040
C1
ECE-V1CS100SR
CAP 10UF 16V VS ELECT SMD
PCE3061CT-ND
$0.1960
C2
ECJ-0EC1H070D
CAP 7.0PF 50V CERAMIC 0402 SMD
PCC070CQCT-ND
$0.0141
C3
ECE-V0JS220WR
CAP 22UF 6.3V ELECT VS SMD
PCE3308CT-ND
$0.1820
C4
ECE-V0JA101SP
CAP 100UF 6.3V ELECT VS SMD
PCE3058CT-ND
$0.2400
C5
ECJ-0EC1H270J
CAP 27PF 50V CERAMIC 0402 SMD
PCC270CQCT-ND
$0.0141
C6
ECJ-0EC1H270J
CAP 27PF 50V CERAMIC 0402 SMD
PCC270CQCT-ND
$0.0141
C7
ECJ-0EB1C103K
CAP 10000PF 16V CERAMIC 0402 SMD
PCC103BQCT-ND
$0.0141
C8
ECJ-0EC1H221J
CAP 220PF 50V CERAMIC 0402 SMD
PCC221CQCT-ND
$0.0141
C9
ECJ-0EC1H221J
CAP 220PF 50V CERAMIC 0402 SMD
PCC221CQCT-ND
$0.0141
C10
ECJ-0EC1H221J
CAP 220PF 50V CERAMIC 0402 SMD
PCC221CQCT-ND
$0.0141
C11
ECE-V1CS100SR
CAP 10UF 16V VS ELECT SMD
PCE3061CT-ND
$0.1960
D1
1PS76SB10 T/R
DIODE SCHOTTKY 30V 200MA SOD323
568-3406-1-ND
$0.0875
D2-13
SLX-LX5093UWC/C
LED 5MM WHITE WATER CLEAR LENS
67-1691-ND
$0.6628
R1
ERJ-3EKF7153V
RES 768K OHM 1/10W 1% 0603 SMD
P768KHCT-ND
$0.0279
R2
ERJ-3EKF9532V
RES 93.1K OHM 1/10W 1% 0603 SMD
P93.1KHCT-ND
$0.0279
R3
ERJ-2RKF5622X
RES 56.2K OHM 1/16W 1% 0402 SMD
P56.2KLCT-ND
$0.0304
R4
ERJ-2RKF4752X
RES 47.5K OHM 1/16W 1% 0402 SMD
P47.5KLCT-ND
$0.0304
S1
MP3-37
PowerFilm MP3-37 3 Volt 50 mA Thin Flexible Solar Module
$5.9500
S2
MP3-37
PowerFilm MP3-37 3 Volt 50 mA Thin Flexible Solar Module
$5.9500
B1
18650
Tenergy Li-Ion 18650 3.7V 2200mAh Battery
$4.8900
Printed Circuit Board
$3.0000
Housing
$7.0000
TOTAL
$47.3365
18
8. Design Review Discussion The design of the runway lighting units has been subject to delays since the very
beginning of the project and related design competition. Parts were difficult to obtain, often
did not work on arrival, and manufacturer technical/engineering support was not readily
available. Development of this design began in Autumn quarter of 2007 with conceptual
design completed at that time, and components tentatively chosen. Design and testing began
Winter quarter of 2008. During this time the evaluation modules for the charging system
were tested, the power distribution switch was tested, and the LED lighting array’s power
consumption measured. Some evaluation of the EZ430-RF2500 EVM was completed using
an evaluation board that a team member personally purchased. A circuit board based on the
reference designs for the various TI components was laid out in EAGLE printed circuit board
CAD and fabricated. Sample components were soldered to the PCBs using a hot air rework
process previously described. Charging, power distribution, and microcontroller systems on
the PCBs functioned properly, but the RF integrated circuits had unpredictable failures.
Problems with the RF system can be attributed to soldering problems because none of the
equipment available to the team is capable of properly heating the CC2500 RFIC. In order to
test these designs an IR reflow oven will have to be purchased or the assembly contracted out
to a prototype facility.
Using the EZ430-RF2500 evaluation modules in place of the MSP430/CC2500 pair on
the circuit boards, RF link can be demonstrated using TI sample code, and as before the
lights can be controlled by accessing the registers of the microcontroller through the debug
interface. However, the lack of documentation on peer to peer networking using the
SIMPLICI-TI networking protocol has further delayed the coding. The code included in this
report is only partially functional, and operates the microcontroller and RF circuitry in fully
active mode such that the system uses too much power to be useful. The pilot-controlled
version will be completed at some time in the future.
Finally an all-analog version of the runway lighting system was constructed due to the
problems with the development of the pilot-controlled version. As described in Appendix B,
the light controlled version uses many of the same parts as the more complex pilot-controlled
version, but uses a comparator to determine the appropriate solar light level for activation.
This version has been tested for 2 weeks during the Spring and is capable of collecting
enough solar energy to operate for an entire night. As this system is built from simple and
proven technology, commercial development may follow a series of full scale field tests to
commence Fall of 2008.
19
Appendix A: Figure A-1: Detailed Control unit schematic
A-1
Figure A-2: Detailed Lighting unit schematic
A-2
Figure A-3: Flow chart for lighting unit..
A-3
Figure A-4: Detailed Physical dimensions and layout of housing.
A-4
Code
Master control unit
#include "bsp.h"
#include "mrfi.h"
#include "nwk_types.h"
#include "nwk_api.h"
#include "bsp_leds.h"
#include "bsp_buttons.h"
#include "vlo_rand.h"
#include "nwk.h"
void linkTo(void);
void MCU_Init(void);
void main (void)
{
WDTCTL = WDTPW + WDTHOLD;
// Stop WDT
{
// delay loop to ensure proper startup before SimpliciTI increases DCO
// This is typically tailored to the power supply used, and in this case
// is overkill for safety due to wide distribution.
volatile int i;
for(i = 0; i < 0xFFFF; i++){}
}
// SimpliciTI will change port pin settings as well
P1DIR = 0xFF;
P1OUT = 0x00;
P2DIR = 0x00;
// P2 will be an input from the hamtronics
P3DIR = 0xC0;
P3OUT = 0x00;
P4DIR = 0xFF;
P4OUT = 0x00;
P1OUT = 0x00;
BSP_Init();
SMPL_Init(0);
linkTo();
}
void linkTo()
{
BSP_TOGGLE_LED1(); //red
BSP_TOGGLE_LED2(); //green
NWK_DELAY(0xFFFF);
NWK_DELAY(0xFFFF);
NWK_DELAY(0xFFFF);
NWK_DELAY(0xFFFF);
NWK_DELAY(0xFFFF);
if (BSP_LED1_IS_ON())
{
A-5
BSP_TOGGLE_LED1();
}
if (BSP_LED2_IS_ON())
{
BSP_TOGGLE_LED2();
}
uint8_t msg[1];
int high = 1, low = 2;
while (1)
{
if (P2OUT == 0x01 || P2OUT == 0x11)
{
if(P2OUT == 0x01)
{
msg[0] = high;
}
else
{
msg[0] = low;
}
//wait "a while"
NWK_DELAY(0xFFFF);
NWK_DELAY(0xFFFF);
// send. doesnt need to be link to anyone they just have to listen
int i = 20; //try for 20 secs
while (SMPL_SUCCESS != SMPL_Send(SMPL_LINKID_USER_UUD, msg, sizeof(msg)&& i >0))
{
int j = 12000;
// Delay 1 sec
do (j--);
while (j > 0);
} //keep trying
}
}
}
/*-----------------------------------------------------------------------------* ADC10 interrupt service routine
------------------------------------------------------------------------------*/
#pragma vector=ADC10_VECTOR
__interrupt void ADC10_ISR(void)
{
__bic_SR_register_on_exit(CPUOFF);
// Clear CPUOFF bit from 0(SR)
}
Lighting unit
#include "bsp.h"
#include "mrfi.h"
#include "nwk_types.h"
#include "nwk_api.h"
#include "bsp_leds.h"
A-6
#include "bsp_buttons.h"
#include "vlo_rand.h"
#include "nwk.h"
void linkTo(void);
void MCU_Init(void);
void main (void)
{
WDTCTL = WDTPW + WDTHOLD;
// Stop WDT
{
// delay loop to ensure proper startup before SimpliciTI increases DCO
// This is typically tailored to the power supply used, and in this case
// is overkill for safety due to wide distribution.
volatile int i;
for(i = 0; i < 0xFFFF; i++){}
}
// SimpliciTI will change port pin settings as well
P1DIR = 0xFF;
P1OUT = 0x00;
P2DIR = 0x3F;
// set P2.3,4 to output direction to control lights
P2OUT = 0x00;
P3DIR = 0xC0;
P3OUT = 0x00;
P4DIR = 0xFF;
P4OUT = 0x00;
P1OUT = 0x00;
//initiate chip
BSP_Init();
TACCR0 = 12000;
// ~ 1 sec
//initiate the SympliciTI network
SMPL_Init(0);
linkTo(); //start main program
}
void linkTo()
{
uint8_t msg[1], len; //define the recieving class
//signal the start main fuction
BSP_TOGGLE_LED1(); //red
BSP_TOGGLE_LED2(); //green
NWK_DELAY(0xFFFF); //delay the lights so they can be seen easley
NWK_DELAY(0xFFFF);
//turn off the LEDs
if (BSP_LED1_IS_ON())
{
BSP_TOGGLE_LED1();
}
if (BSP_LED2_IS_ON())
{
BSP_TOGGLE_LED2();
A-7
}
int ONLOW = 1, ONHIGH = 2; // set the light conditions
while(1) //main loop
{
BSP_TOGGLE_LED2(); //green -signal in main loop waiting for a recieved transmission
NWK_DELAY(0xFFFF);
NWK_DELAY(0xFFFF); //delay the lights so they can be seen easley
NWK_DELAY(0xFFFF);
if (BSP_LED2_IS_ON())
{
BSP_TOGGLE_LED2();
}
NWK_DELAY(0xFFFF);
NWK_DELAY(0xFFFF);//delay the lights so they can be seen easley
NWK_DELAY(0xFFFF);
//this will accept a message from any device they do not have to be link
if (SMPL_SUCCESS == SMPL_Receive(SMPL_LINKID_USER_UUD, msg, &len)) //did we recieve a message?
{
if (len && (msg[0] == ONHIGH || msg[0] == ONLOW)) //is it valide
{
if(msg[0] == ONHIGH)//need lights on high?
{
P2OUT |= 0x18; //turn lights on high
}
else //else they go on low
{
P2OUT |= 0x08; //turn lights on low
}
int i = 30, sent = 0; //for at least 30 sec try to send to next device for 30 secs
while(i > 0 && sent == 0)
{
BSP_TOGGLE_LED2(); //green- try to send the received message
int j = 12000;
// Delay 1 sec
do{
j--;
//this will try to send a message to any device without being link
//the recieving device only has to be listening
if(SMPL_SUCCESS == SMPL_Send(SMPL_LINKID_USER_UUD, msg, sizeof(msg))) //was the sending a success?
{
//if yes then stop trying
//wait "a while"
NWK_DELAY(0xFFFF);
NWK_DELAY(0xFFFF);//delay the lights so they can be seen easley
NWK_DELAY(0xFFFF);
BSP_TOGGLE_LED1(); //red -recieved message sent
NWK_DELAY(0xFFFF);
NWK_DELAY(0xFFFF);//delay the lights so they can be seen easley
NWK_DELAY(0xFFFF);
if (BSP_LED1_IS_ON())
{
BSP_TOGGLE_LED1();
}
sent = 1;
}
A-8
}while (j != 0 && sent == 0);
i--;
}
i = 270; // Delay 4min 30 secs
//keep lights in for another 4 min 30 sec
do{
i--;
int j = 12000;
do (j--);
while (j != 0);
}while (i != 0);
// Delay 1 sec
//after 4 min 30 sec start too flash lights
if(msg[1] == ONHIGH)//if lights on high flash high
{
// toggle turn-on high
for(i = 30;i > 0; i--) // Delay 30 sec
{
P2OUT ^= 0x18;
int j = 12000;
do (j--);
while (j != 0);
// Delay 1 sec
}
P2OUT &= ~0x18;
// Clear P2.0 LED off - lighst off
}
else//else flash lighst low
{
// toggle turn-on low
for(i = 30;i > 0; i--) // Delay 30 sec
{
P2OUT ^= 0x08;
int j = 12000;
do (j--);
while (j != 0);
}
P2OUT &= ~0x08;
// Delay 1 sec
// Clear P2.0 LED off- lights off
}
}
}
//if no message recieved or a message was just handled then sleep for 1 sec
SMPL_Ioctl( IOCTL_OBJ_RADIO, IOCTL_ACT_RADIO_SLEEP, "" );
__bis_SR_register(LPM3_bits+GIE);
// LPM3 with interrupts enabled
SMPL_Ioctl( IOCTL_OBJ_RADIO, IOCTL_ACT_RADIO_AWAKE, "" );
}
}
/*-----------------------------------------------------------------------------* ADC10 interrupt service routine
------------------------------------------------------------------------------*/
#pragma vector=ADC10_VECTOR
__interrupt void ADC10_ISR(void)
{
__bic_SR_register_on_exit(CPUOFF);
// Clear CPUOFF bit from 0(SR)
}
A-9
/*-----------------------------------------------------------------------------* Timer A0 interrupt service routine
------------------------------------------------------------------------------*/
#pragma vector=TIMERA0_VECTOR
__interrupt void Timer_A (void)
{
__bic_SR_register_on_exit(LPM3_bits);
// Clear LPM3 bit from 0(SR)
}
A-10
Appendix B: Light Level Controlled Runway Lighting Unit
System Design
A “pure hardware” design was desired due to delays in the coding for the radio controlled
lighting system, resulting in the light controlled variant of the previously described system. This
design can be built using modified printed circuit boards designed for the radio controlled
system, and also required four integrated circuits.
Components Used
TI- TPS6205x
The TPS6205x is a 95% efficient synchronous step-down converter. The device pulses
current through an external inductor based on an internal frequency reference that is
typically 850kHz. The compact MSOP-10 package is capable of handling 800mA output
current, and is available in fixed-voltage and adjustable-voltage versions.
TI- TPS2090D
The TPS2090D is a dual channel switch using a pair of 70 mΩ N-channel MOSFET
power switches whose gates are driven by an internal charge pump resulting in complete
isolation between the control side and the power side of the IC. The TPS2090D is
current limited to 500mA and has an undervoltage lockout at 2.7V which would
theoretically prevent damage to the Li-Ion cell from excessive discharge.
TI- TLV3492
The TLV3492 is a dual channel, push-pull output, comparator. The device operates on
supply voltages as low as 1.8V using CMOS technology, and has an extremely low
supply current of 0.8μV, and is referred to as a nanopower device.
Solar energy is collected by four PowerFilm MP3-37 thin film photovoltaic cells
configured as 6V pairs. This configuration yields 6V at 100mA into the TPS62050 DC/DC buck
converter under full direct sunlight. The DC/DC converter is set to 4.5V and charges a Tenergy
18650 Li-Ion cell through a Schottky diode for isolation.
The battery provides power to a TLV3492 dual channel low power comparator which
compares the voltage output from the solar cells to a 0.3V reference set by a Schottky diode. If
the solar cell voltage drops below 0.3V, then output one goes high. Using the photovoltaic cell
as a light reference allows the standard resistive photocell to be omitted. The other channel
compares the battery voltage to a 2.7V Zener diode voltage reference, and output two goes low
when required to protect the lithium cell.
The TLV3492 comparator drives a TPS2090D dual channel power distribution switch.
Channel one of the chip closes when the comparator detects that the ambient light is low enough
B-1
to turn on the LED array. The output of channel one is looped back to the power input of
channel two, which is closed when the comparator determines that the lithium cell has sufficient
voltage.
The TPS2090D drives the input of a TPS62056 fixed voltage DC/DC buck converter.
The TPS62056 is set to output 3.3VDC nominal at 95% efficiency, and in this application is
delivering 3.1V to the LED array comprised of eight white LEDs. The power converter
maintains the LED array at a constant light level for most of the runtime and by reducing voltage
drain reduces the current draw.
Figure B-1: Light Controlled Runway Light--System Schematic
Power Analysis
Unlike the radio controlled version of the lighting system, the light controlled version
must capture significantly more solar energy. Four of the MP3-37 photovoltaic cells are used on
this design rather than the two cells in the radio controlled version. This configuration yields
6VDC at 100mA in direct sunlight. The more robust four cell design is able to capture still
significant energy under obscured sunlight. Power outputs of 50mA can be observed on days
when the cloud ceiling can be described as broken, and 25mA under an overcast layer. Usable
charging current has been observed under a thick, low altitude overcast. Assuming 100mA for
four hours and partial sunlight providing 40mA for eight hours, the power stored in the battery is
as follows: Etotal = ∑ E DIRECT + E INDIRECT = 4(100mA) + 8(40mA) = 720mAh
The power consumption of the control circuitry is 0.24mA in the off-state. Power
consumption with the LED array activated is 95mA. Based on the 720mAh delivered to the
battery during the charge cycle, the effective runtime of the lighting unit is just under eight
hours. As cell voltage decreases so does the current draw from the LED array, and visible light
can still be observed after a 10 hour runtime.
Cost Analysis
The light controlled version of the runway lighting unit uses the same housing as the
radio controlled design which is described in Section 4.6. For test and evaluation purposes the
same printed circuit board can be used, although this design requires less board area for
implementation.
B-2
Table B-1: Light-Controlled Lighting Unit Bill of Materials
Part Ref.
Mfg. Part #
Description
DK P/N
Unit Price
U1
TPS62050DGSR
IC STEP-DOWN CONV HI-EFF 10-MSOP
296-14392-1-ND
$2.4600
U2
TLV3492AID
IC COMPARATOR P-P NANOPWR 8-SOIC
296-14054-5-ND
$0.8700
U3
TPS2090D
IC POWER DIST SWITCH DUAL 8-SOIC
296-3437-5-ND
$0.9100
U4
TPS62056DGSR
IC STEP-DOWN CONV HI-EFF 10-MSOP
296-14212-5-ND
$2.4600
L1
SLF7032T-100M1R4-2-PF
INDUCTOR SHIELD PWR 10UH 7032
445-1998-1-ND
$0.9650
L2
SLF7032T-100M1R4-2-PF
INDUCTOR SHIELD PWR 10UH 7032
445-1998-1-ND
$0.9650
C1
ECE-V1CS100SR
CAP 10UF 16V VS ELECT SMD
PCE3061CT-ND
$0.1960
C2
ECJ-0EC1H070D
CAP 7.0PF 50V CERAMIC 0402 SMD
PCC070CQCT-ND
$0.0141
C3
ECE-V0JS220WR
CAP 22UF 6.3V ELECT VS SMD
PCE3308CT-ND
$0.1820
C4
ECE-V1CS100SR
CAP 10UF 16V VS ELECT SMD
PCE3061CT-ND
$0.1960
C5
ECE-V0JS220WR
CAP 22UF 6.3V ELECT VS SMD
PCE3308CT-ND
$0.1820
D1
1PS76SB10 T/R
DIODE SCHOTTKY 30V 200MA SOD323
568-3406-1-ND
$0.0875
D2
MAZ30270HL
DIODE ZENER 2.7V 200MW MINI 3P
MAZ30270HLCT-ND
$0.2050
D3-11
SLX-LX5093UWC/C
LED 5MM WHITE WATER CLEAR LENS
67-1691-ND
$0.6628
R1
ERJ-3EKF7153V
RES 768K OHM 1/10W 1% 0603 SMD
P768KHCT-ND
$0.0279
R2
ERJ-3EKF9532V
RES 93.1K OHM 1/10W 1% 0603 SMD
P93.1KHCT-ND
$0.0279
R3
ERJ-3EKF2802V
RES 28.0K OHM 1/10W 1% 0603 SMD
P28.0KHCT-ND
$0.0279
R4
ERJ-3EKF2802V
RES 28.0K OHM 1/10W 1% 0603 SMD
P28.0KHCT-ND
$0.0279
S1
MP3-37
PowerFilm MP3-37 3 Volt 50 mA Thin Flexible Solar Module
$5.9500
S2
MP3-37
PowerFilm MP3-37 3 Volt 50 mA Thin Flexible Solar Module
$5.9500
S3
MP3-37
PowerFilm MP3-37 3 Volt 50 mA Thin Flexible Solar Module
$5.9500
S4
MP3-37
PowerFilm MP3-37 3 Volt 50 mA Thin Flexible Solar Module
$5.9500
B1
18650
Tenergy Li-Ion 18650 3.7V 2200mAh Battery
$4.8900
Printed Circuit Board
$3.0000
Housing
$7.0000
Total Cost
$49.1568
Performance Analysis
The light controlled version of the runway lighting system has a demonstrated runtime of
10 hours when operated in the summer months when the daylight period is 14 hours and the
night 10 hours. This means that the runway lighting system is proven acceptable for use in the
tested region of 40° North Latitude during the Spring/Summer months. This system would be
effective for VFR (visual flight rules) use when supplemental runway lighting would be a safety
benefit to the pilot. Given that most recreational night flights are conducted at twilight or no
more than several hours afterward, this would be extremely effective for lighting a grass runway.
B-3
Figure B-2: Light-Controlled Lighting Unit Prototype
B-4
Figure B-3: Light-Controlled System Schematic (Full Size)
B-5
5
R2
93.1 K
R1
768 K
C2
7.0 pF
4
D1
C3
22 uF
1PS76SB10
T18650 Li-Ion
3.7V
D2
1PS76SB10
R3
27K
4
2
3
1
V-
MIN A
PIN A
OUT A
V+
3
MIN B
PIN B
OUT B
U2
TLV3492AID
6
5
7
8
R4 27K
D3
2.7V
1
5
4
2
GND
EN2_
EN1_
IN1
OUT2
IN2
OUT1
OC*
U3
TPS2090D
6
3
7
8
2
C4
10 uF
7
6
8
1
2
4
5
9
L2
10 uH
C5
22 uF
RWL-2 Light Controlled Runway Lighting Unit
PGND
GND
Title
LBO
PG
FB
SYNC
LBI
EN
SW
U4
TPS62056DGS
VIN
Date:
Size
B
Monday, May 19, 2008
Document Number
<Doc>
1
Sheet
1
of
1
Rev
A
A
10 uH
D
A
2
4
L1
1
B
LBO
PGND
GND
PG
SYNC
LBI
FB
9
5
2
B
7
6
EN
SW
3
C
C1
10 uF
8
3
C
MP3-37
3V / 50mA
U1
TPS62050DGS
VIN
10
1
4
3
D
5
10