Transcript Remote Fire Alarm

Remote Fire Alarm
Nick Rymer
Brian Robinson
Adam Lehotay
Josh Bertovich
Introduction
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Problem
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Location with Multiple Buildings
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Unmanned Buildings
Buildings hundreds of feet apart
Introduction
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Existing Systems
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Stand Alone Alarms
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Someone Must Hear Alarm
Hardwired
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Complex and Expensive
Inflexible
Solution
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Wireless System
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Easy Installation
Can Monitor Many Buildings
1 unit can Monitor Entire System
Principle of Operation
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1 Central Unit
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Displays Information About Entire System
Up to 8 Remote Fire Alarms
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Transmit Status to Central Unit
Central Unit
Remote Unit
Remote System
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Remote Alarm Status
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Normal Operation
Fire
Low Battery
Communication Loss
Adding Devices
Removing Devices
Performance Specification
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User-friendly installation, setup, and operation
Performance Specification
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Central and Remote Units will be powered by
120 VAC
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Battery backup in the Remote Units
Maximum of eight remote units controlled by
one central unit
The status of all remote units will be known
by the central unit in less than one second
Remote Units will detect smoke with
ionization chambers
Performance Specification
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Maximum communication distance
between central unit and remote unit
will be 500 feet with obstructions
System Design
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Block Diagram of
Remote Unit
Standard
Electrical
Outlet
120
VAC
AC-DC
adapter
Remote Alarm Unit
6Volt
Battery
6V
DC
5 Volt
Power
Regulator
Internal
Switch
+5V
Speaker
RF Output
RF Input
+5V
Test
Switch
Ionization
Chamber
Central
Unit
5 Volts
Regulated
Ion chamber
status
Siren Signal,
To sound
alarm
Signal to Central
Unit
Transceiver
Decoded Signal
from Central unit
IC Smoke
Detector
chip
Ion chamber
status
PIC
Control Unit
User
Switch
Remote Unit PIC Operation
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Infinite loop which checks the status of I/O
pins on the PIC
Devices being checked on I/O pins
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Transceiver
IC Smoke Detector Chip (Ionization chamber and
battery level monitoring)
Learn Button
Abnormal events on a device cause a subfunction to be called
Fire Alert Function
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Invoked when a local fire is detected
The local alarm is sounded and the Central
Unit is notified of event
Remote Fire Function
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Executed when there is a fire at another
location
Transceiver receives signal from Central Unit
to sound alarm
Low Battery Alert Function
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Executed when
battery power
drops near
minimum
operational
levels
Receives alert
from IC Smoke
Detector Chip
and transceiver
sends alert to
central unit
Learn Function
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Executed when the user presses the learn button on
the local unit
Transceiver sends signal to Central Unit
Central Unit sends signal containing the network
address that the unit will respond to when polled
Central Unit Block Diagram
Standard
Electrical
Outlet
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Central Unit
120
VAC
AC-DC
adapter
5 Volt
Power
Regulator
6V DC
8 User
Switches
Remove
Button
Learn
Button
Remote
Unit
RF Output
RF Input
5 Volts
Regulated
Encoder
LCD
Encoded
Input
Signal to Remote
Unit
Transceiver
+5V
User Input
Decoded Signal
from Remote unit
Display
Information
PIC
Control Unit
Analog
Output
Speaker
8 LED
Lights
Shows connectivity
of central unit’s
components
AC-DC Adaptor
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Converts AC output from a standard 60
Hz 120 VAC electrical outlet into 6 Volts
DC
The output of this block is the input to
the 5 volt regulator block
Power Regulator
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Regulates the voltage so chips will function
normally as well as be protected from over
voltage
Regulator holds the voltage at 5 volts ±5%
Remote unit’s regulator will do the same as
the central unit’s regulator except that it will
regulate power for fewer devices
Internal Switch
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Internal switch has inputs from the
battery and AC-DC adapter
Switch connects either the battery or the
AC-DC adapter to the regulator
Battery will only be connected to the
regulator when the AC-DC adapter is no
longer providing a 6 VDC input to the
switch
Transceiver
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FM modulation at 900 MHz
8-bit data packets represent either a
remote unit address, central unit
address, or a certain function to be
executed
RS-232 protocol used to transferred
data between transceiver and
microcontroller
Transceiver
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RF data received by transceiver
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Data-out buffer
Request-to-send
Data from microcontroller
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Data-in buffer
Clear-to-send
Modes of Operation
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Sleep mode
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Transmit mode
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Transceiver takes the data from the data-in buffer
and broadcasts it to the other transceiver
Receive mode
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Low power consumption
Transceiver receives data from the other
transceivers and stores it in the data-out buffer
Transition mode
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Transition time between modes
Modes of Operation
Utilizing Modes of Operation
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Modes of operation should be used
efficiently to save power
Transceivers in sleep mode 99% of the
time
Central unit transceiver polls the next
remote transceiver every second
Central Unit PIC Operation
Purpose:
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Manages communication with remote devices
Maintains identification for each remote device
Processes and responds to user input
Controls the display
Central Unit PIC I/O
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Infinite loop which checks the status of I/O pins on the PIC
Devices sending information to input pins
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Transceiver
Learn/Remove Buttons
Alarm Specific Buttons
Devices receiving information from output pins
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Transceiver
LCD display
Alarm LEDs and speaker
Fire Alert Process
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Performed when fire detection is received from
transceiver
Sends signal to trigger all remote devices
Displays fire detection message and alarm of
concern on the display
Low Battery Process
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Performed when low battery is received from
transceiver
Displays low battery message and alarm of concern
on the display
New Device Process
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Performed when user presses the learn button
Halts normal operation
Selects and transmits identification for new device
Waits for new device to confirm its identity
Normal operation is restored
Remove Device Process
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Performed when user pushes the remove button and
selects an alarm
Requires user confirmation and then the selected
alarm identification is cleared
Comm. Loss Process
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Performed when a remote device does not respond
to a status prompt
Displays communication loss message and alarm of
concern on the display
Performance Analysis
Central Unit Power Consumption
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Typical Power used by Central Unit
Power = ITyp * 5V, 165mA * 5V
.825 Watts
Maximum Power used by Central Unit
 Power = ITyp* 5V, 720mA * 5V
3.6 Watts
Maximum Power Supplied AC-DC adapter
 Power = IMAX * 6V, 1A * 6V
6 Watts
Maximum Power Supplied by Regulator
Power = IMAX * 5V, 1A * 5V
5 Watts
Excess Capacity
 AC-DC adapter Supplies 2.4 Watts of Extra Power
 Regulator loses 1 Watt of Power in Heat
 Regulator Provides 1.4 Watts of extra Power to Central Unit
Performance Analysis
Remote Unit Power Consumption
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Typical Power used by Remote Unit
Power = ITyp * 5V, 15mA * 5V
.075 Watts
Maximum Power used by Remote Unit
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Power = ITyp* 5V, 590mA * 5V
2.95 Watts
Maximum Power Supplied by rectifier
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Power = IMAX * 6V, 1A * 6V
6 Watts
Maximum Power Supplied by Regulator
Power = IMAX * 5V, 1A * 5V
5 Watts
Excess Capacity
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Ac-Dc adapter Supplies 3.05 Watts of Extra Power
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Regulator loses 1 Watt of Power in Heat
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Regulator Provides 2.05 Watts of extra Power to Remote Unit
Battery Life Calculations
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Standard 4 AA Battery Life = 6V @ 1300 Milliamp Hours
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Central Unit Battery Life @ Typical Current
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I = 1300 / 15 = 86.67 Hours
Performance Analysis
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Transceiver Performance
Transmit power output of 140 mW
 Receiver sensitivity of -114 dBm
 Transmission range can reach up to 1500 feet
 The serial data throughput is approximately 1100 bps
Excess capacity
 1000 feet extended range beyond required range
 only a fraction of the data throughput will be needed
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Performance Analysis
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PIC Performance (Central and Remote Units)
256k of program memory
 PIC will be set to run at 2MHz
Excess capacity
 Small amounts of memory will be required relative to the available
256k
 At 2MHz will be processing data at a much faster rate than would
be required to meet time constraints of the system
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