Download EE 413 Communication Electronics

EE 413
Communication Electronics
Capstone Design Project
(Motion Detector Alarm Dialer)
Instructor
Dr. Pao Lo Liu
Group Members
Chee Fai NG (3032-0373)
Jia Quan Cheok (3032-6421)
EE Department
University at Buffalo
Project Title: Automatic Dial Alarm
System
Objectives: To design and build application circuits
using microcontroller.
 To understand how a dial alarm system
work.
 To build a motion detector and understand
how it work.
 To learn and understand PIC language
which use to program the microcontroller.
How The Dial Alarm Circuit Work
 This dial alarm system consists of motion
detector as an input.
 A trigger pulse will send by the motion
detector once it sense any movement
occurs within the coverage area.
 This trigger pulse will turn on a BC 557
transistor and deliver power to
microcontroller.
 Microcontroller will then start to execute
the program.
How The Dial Alarm Circuit Work
(Cont.)
 The LED in the opto-coupler will be turns on and
causes the line to be “picked up” by using a high
gain Darlington transistor.
 The microcontroller then dials two pre set phone
numbers to alert the listener by sent down a
“Hee Haw” signal.
 A microphone with high gain amplifier also
connected to the phone line to detect
conversation or movement in the target area.
 The two numbers are then called again before
the alarm closes down.
Dial Alarm Circuit
Dial Alarm Circuit
Dial Alarm Circuit (Cont.)
 Turn on circuit
 Tone detector
 DTMF wave shaping circuit
 High gain audio amplifier
 Opto-coupler
 Microcontroller
Turn On Circuit
 Need 6v power supply.
 Turn on the circuit by motion detector
 Microcontroller, diode and 100k resistor
are the component use to keep the “turn
on” circuit on.
 To ensure the alarm only carries out one
alarm operation and resets and ready for
another trigger pulse, the trigger device
must be AC coupled to the circuit.
 The “turn on” circuit work by charging the
top electrolytic
 Energy from the electrolytic flows into the
base of the BC557 transistor and allows
current to flow between collector and
emitter leads and activates the rest of the
project.
Tone Detector
 Use to detect any tone about 500Hz on the






phone line like DTMF.
Alarm will be turn off when tone is detected.
The circuit amplifies the signal on the
phone line and turns on a transistor.
Biasing components keep the transistor off.
When there is a signal, the transistor turns
on and collector goes low and cause the
4.7uF electrolytic discharged via diode.
At the same time, the 4.7uF electrolytic is
getting charged via 100k resistor.
The electrolytic will be fully discharged and
will be detected by the microcontroller as
low if the frequency of the signal is high
enough.
DTMF wave-shaping circuit
 Dual Tone Multiple Frequency (DTMF) –




waveform must be in sine wave.
To convert a square wave into sine wave
produce by the microcontroller.
Waveform is form by charging and
discharging capacitor by using a
resistor.
Two tones are produced separately by
the microcontroller and then combined
after wave shaping in order to reduce
the interference between the two
waveforms.
The 10mH choke is used to smooth out
the shape of the waveform and
increased the dialing accuracy.
High Gain Audio Amplifier
 Build by two transistors which used to pick






up sounds in the target area during the
alarm activation.
It is directly coupled to the phone line via a
bridge.
Any change in impedance of any
components connected to the phone line
will cause signal sent down the line.
A 20mV signal from the microphone will
produce 1000mV signal on the collector of
the first transistor and passed to the output
transistor.
Amplitude of the waveform across the
output transistor is about 2-3V.
The pre-amplifier section is powered by
the 5V supply where as the output
transistor is driven from the phone line.
Audio amplifier is off when the DTMF tone
is sent down the line.
Opto-coupler
 It is used to picks up the phone line.
 The LED in the opto-coupler will be turned
on when the motion sensor is activated.
 The LED turns on a phototransistor inside
the opto-coupler and reduces the resistance
between collector and emitter leads of the
phototransistor and this pulls the base of a
Darlington transistor towards the positive
rail.
Microcontroller
 It is an 8-pin chip with 5
input/output lines and one outputonly line.
 The output lines change from
low-to-high-to-low very fast.
 The program set inside the
microcontroller determines what
happens on each lines and parts
around it are use to adapt or
modify or amplify a signal to suit
the microcontroller or phone line.
Flow Chart
Start
DTMF 1st Number
Detect Audio
Hee Haw
Hee Haw
Detect Audio
Turn Off
DTMF 2nd Number
Detect Audio
Hee Haw
Detect Audio
Hee Haw
Turn Off
End
Repeat
second
time
Multi Chip Programmer
What used to trigger the Dial Alarm
System?
 Temperature/Voltage Level module
 Monitor temperature or voltage level presets
 Pressure map
 Listen-in Module
 Listen in to the area being protected
 Motion Module
 Detect moving persons and trigger the Dial Alarm.
PIR Movement Detector
 Pyro-electric infra-red movement detector centers
around a Pyro-electric(‘body heat’) infra-red sensor & a
KC778B controller chip.
 KC778B  provides amplification, filtering, clock,
comparators a daylight detector and a voltage regulator.
 PIR sensor  three lead high impedance sensor.
 Requires a Fresnel beam focusing lens.
 Fresnel lens  break up observation area into optical zones so a
heat source moving from one optical zone to another generate heat
waves on PIR detector’s surface.
 Lower gain circuit & excellent lens system
PIR Detector Schematic
Circuit Description
 There are three main sensitivity controls
built into circuit:-
 Movement Sensitivity:
 Heart of this part  PIR sensor
 Connected to pin 2, 7, & 8 of the
KC778B.
 Pin 7  pyro drain reference, Pin 8 
pyro source input.
 Control/adjust the sensitivity/”range” for
the PIR sensors.
 The sensitivity controlled at pin 2, which
is a PIR sensitivity input pin.
 Using a trimpot (potentiometer),
P1(referred in the previous circuit)
 When P1 adjusted where equals the
sensor drain potential (pin 7) (~0.5V),
sensitivity max. When connected to
ground,(~0.125V), sensitivity min.
 Daylight Sensitivity:
 Adjust the sensor to be active for just the night
and inactive during the daytime.
 This sensitivity controlled by another trimpot
P2 and a LDR (light dependent resistor) which
is connected to pin 12 on the microchip. (pin12
 silicon photo diode input pin)
 P2 used to control how sensitivity the LDR to
be against light.
 LDR has very high resistance (million of ohms)
when no light, and significantly low resistance
when illuminated (hundred of ohms).
 The Toggle terminal been configured to give
user an exit delay about 30s so have time to
leave the room after turning it on.
 Optional feature
 Could be disable by connect pin 12 to Vcc.
 Pulse on-time Adjust:
 This part adjust the output pulse
from between 1.5 seconds upwards
when movement detected.
 The amount of time delay controlled
by another trimpot P3 connected at
pin 18 &19 of the KC778B chip (off
timer OSC pins).
 Minimum time delay can be build by
connect directly the pins 18 & 19
with no external capacitors and
resistors.
 A terminal block then connected
from the output pin from the chip
where output signal from here is
connected to the input of the Dial
Alarm circuit.
KC 778B Controller Chip
Sensitivity Adj
Offset
Filter
Pyro
(S)
Gain
Select
DC Cap
Pyro
(D)
Anti Alias
Fref
R
C
Daylight Sense
Daylight Adjust
PIR Front End
Amplifiers &
Noise
cancellation
circuit
Oscillator &
Synchronizatio
n Citcuitry
Daylight
Detector
Amplifier and
Comparator
Switched
capacitor
Bandpass
Filter
Threshold
comparators
& Timing
circuitry
Voltage
Regulator
LED
OUTPUT
V Reg
KC 778B Controller Chip (Cont’d)
 The heart of the whole circuit as the motion detection IC.
 Optimum with the electrical signals from the PIR sensors
which have very low frequency (0.1 to 10 Hz) and
bandwidth.
 Operating voltage is 4 – 15V.
 With the 78L05 voltage regulator we connected in pin
1(Vcc), the input voltage should be around 9 – 12V.
PIR Movement Detector (building and
testing)
 When building up the system, we used ~2.5” by 3.5” PC




Board.
Be aware of the right polarity of capacitors, transistor,
LEDs and the PIR sensors.
Components especially the controller chip and PIR
sensor could damaged easily it placed incorrectly.
The PIR sensor, LDR and Fresnel lens are mounted on
the copper side of PCB (opposite side of all components)
So, the system be easily placed (e.g. in a box) with the
lens poking out with the electronics on top of the PCB for
easy access.
All components except PIR sensor,
LDR and Fresnel lens on top of PCB
PIR sensor, LDR and Fresnel lens
mounted back of PCB
 After building the whole circuit, we tested it in the





electronics lab.
We applied a 9V transistor battery to Vcc pin of
the chip.
Connect a voltmeter to the Output pin.
When power applied, waited about 30 seconds
and wave hand in front of PIR sensor.
The LED indicator light, and the Voltmeter from
the output jump from zero volts to 9 volts in the
screen.
When no movement detected, the LED light off
and the voltmeter value back to zero.
Graphs Obtained from Testing
 needed warm up
 30 seconds exit delay by
10
9V
On
9
18s
8
7
Output Voltage, V(V)
the configured toggle
terminal block (pin15 on
chip) – detector not
operate.
 Movement detected –
LED light ~20s where the
output voltage ~ 9V.
 No movement – LED light
off where output voltage
~ 0V.
Output Voltage Vs Time
6
Output Volatge (V)
5
4
3
2
22s
1
0.57
V up
Warm
Off
0
0
20
40
60
80
Time, t(s)
100
120
140
 Finally the PIR movement detector ready
to be cascade to the Dial Alarm circuit!
 Became a Motion Detector Alarm Dialer!
Question???