火灾自动报警系统(英文)

2021年1月25日发(作者：elegance)
Automatic fire alarm system based on MCU

Abstract:
The paper introduced an automatic warehouse fire a1arm system based
on MCU. The system was mainly made up of ATmega16, temperature sensors, smoke
sensors, and EX-1 auto dialed alarm module. In the system, temperature signals were
transformed to serial data, and smoke signals were transformed to voltage signals. All
the
data
were
processed
by
MCU.
When
the
surveillance
system
checked
fire
in
warehouse,
alarm
signal
was
turn
on,
meanwhile
the
messages
were
transmitted
to
managers through EX-1. Application of the system was convenient to deal with fire
in- time, efficiently by warehouse manager.
Keywords:
fire
alarm
transducer;smoke
sensor
system;ATmega16;temperature
transducer;smoke sensor
I. INTRODUCTION

Automatic fire alarm control system has experienced a process from the simple
to
the
complex
and
intelligence
system
increasingly
in
China.
The
characteristic
is
automatic
fire
detection
and
alarm
technology
has
a
great
progress
along
with
computing
and
detection
technology
development.
At
present,
automatic
fire
alarm
control
system
was
used
in
bulk
storage
plant,
shopping
malls,
high-level
office
buildings, hotels and other places. They were used in a number of collections focused
on one area of intelligent alarm control method with higher levels of bus-type alarm
control system, and in some residential areas and commercial buildings were installed
by a single automatic fire alarm detection device. These alarm detection devices fail
to
report
sometimes,
or
misinformation.
Its
reliability
is
not
high
because
of
using
single
sensor.
Therefore,
it
is
needed
to
develop
a
simple
structure,
low
cost,
high
reliability, fast responding, automatic fire detection system.

II. GENERAL PROJECT OF THE SYSTEM


The hardware block diagram shown in Figure 1, hardware by temperature sensors,
smoke sensors, signal processing module, MCU modules and automatic alarm module.
Non electrical quantity that is through the sensing element sensors

(smoke sensors
and temperature sensors) will be on-site temperature, smoke and other non- electrical
signal
into
an
electrical
signal,
as
well
as
signals
for
signal
processing
to
convert
analog
quantity
to
digital
quantity.
Finally,
the
sampled
data
were
processed
and
compared with the limits by MCU system. This system can produce local and remote
auto-alarm signals.
































Temperature







Ionization


































Transducer









smoke detector


















































































signal





















































processing


PD0



SCM


auto alarm

module
PD1















































T ephoneel

Inter f ace























…


Figure 1. Automatic fire alarm system structure
Ⅲ
. THE HARDWARE COMPONENTS
A. Atmega16
The system used by the U.S. Atmel’s microcontroller
ATmega16 microcontroller.
ATmega16
is
based
on
the
AVR
RISC
architecture
to
enhance
low-power
8-bit
CMOS
microcontroller.
Because
of
its
advanced
instruction
set
and
a
single
clock
cycle instruction execution time, ATmega16 data throughput of up to 1 MIPS / MHz.
Thereby
mitigate
the
system
in
the
power
and
the
contradiction
between
the
processing
rate.
ATmega16
has
the
following
characteristics:
16K
bytes
in- system
programmable
Flash
(with
the
ability
to
read
and
write
at
the
same
time,
that
is,
RWW), 512 bytes EEPROM, 1K bytes SRAM, 32 general-purpose I / O port lines, 32
general-purpose working registers, for the JTAG boundary scan interface, support the
on- chip debugging and programming, 3 has a more flexible mode of timer / counter
(T
/
C),
chip
internal
/
external
interrupts,
programmable
serial
USART,
there
are
initial
conditions
detector
universal
serial
interface,
8-channel
10-bit
with
optional
differential input stage programmable gain (TQFP package) of the ADC, with on-chip
oscillator of programmable watchdog timer, an SPI serial port, as well as six can be
selected by software power-saving mode.
The
chip
is
based
on
Atmel
high-density
nonvolatile
memory
technology
production
on-chip
ISP
Flash
allows
the
program
memory
through
the
ISP
serial
interface or a general-purpose programmer for programming; you can also run on the
AVR
core
among
the
bootstrap
to
program.
Boot
program
can
use
any
interface
to
download
the
application
to
the
Flash
memory
area
(Application
Flash
Memory).
Application
of
Flash
storage
area
is
updated
when
the
boot
Flash
area
(Boot
Flash
Memory) program continues to run, RWW operation achieved. ATmega16 to become
a powerful microcontroller by 8-bit RISC CPU and the system programmable flash in
a
single
chip,
for
many
embedded
control
applications
provides
a
flexible
and
cost-effective solution. ATmega16 has a set of programming and system development
tools, including: C language compiler, macro assembler, program debugger / software
emulator, emulators and evaluation boards.
B. Temperature Sensor



Temperature sensor manufactured by DALLAS Semiconductor DS18B20-type
single intelligence temperature sensor, its performance features include:
1)This sensor have single-bus- specific technology, either through the serial port
cable
also
through
other
I
/
O
port
lines
and
computer
interfaces,without
going
through
other
conversion
circuits
Direct
output
measured
temperature
value
(9-bit
binary number, with sign bit).
2)
Temperature
range
is
-55
℃

~
+125
℃
,
measurement
resolution
of
0.
0625
℃
.
3) Containing 64 as amended through the laser-read-only memory ROM.
4) Fit a variety of SCM or system machine.
5) Users can set separate ways each temperature upper and lower limit.
6) Includes parasitic power.


DS18B20 and the main chip connection diagram shown in Figure 2: DS18B20
number one pin grounded, then on the 3
rd
pin high and the 2
nd
pin then a 5. 1K of the
pull-up
resistor,
at
the
same
time
received
a
single
output
signal
of
the
PD0
pin.
Pull-up is to pull the uncertainty signal through a resistor embedded in the high places,
resistance
at
the
same
time
current
－
limited .
Program
from
the
DQ
pin
in
high
impedance
state
to
ensure
that
the
beginning,
so
that
you
can
pull
on
the
pull- up
resistor to the high DQ. At the same time the main chip also can be an external site
alarm buzzer.
















Figure 2. ds18b20 and the main chip connection diagram.

C. Smoke Monitoring Module




Smoke sensors choose HIS-07 ion
smoke detectors
when the flow through the
inside
and
outside
the
ionization
chamber
ionization
electron
flow
is
unbalanced,
collector
charges
current
until
the
ionization
balance.
In
a
smoke-free
or
non-combustion, the collector being subject to the impact ionization current statistical
fluctuation, the potential to maintain a balance. Ionization current have impact when
the
smoke
into
the
ionization
chamber,
easily
into
the
ionization
chamber
smoke
outside than inside the ionization chamber of the affected, ionization current decline
in and collector to re-charge until the new equilibrium potential, this potential change
can be used to trigger the alarm circuit. Technical parameters such as Table 1.



TABLE -07 ION SMOKE SENSOR THCHNICAL DATA

















Table Head












Table Column head













Equilibrium potential collector





Smoke
signals
are
processed
on
the
chip
of
choice
is
the
Motorola
company’s
MC14468, MC14468 for DIP 16-pin package, contain oscillator, timer, latch, alarm
control logic circuit, high input impedance comparator etc. When not detected smoke,
MC14468 internal oscillator that oscillation cycle 1.67s. Each 1.67s cycle the internal
power supply is
provided to the work of the entire chip. It’s all kept detect any
smoke
in
addition
to
LED
flashes,
battery
voltage
alarm
and
smoke
alarm.
The
oscillator
oscillation period becomes 40ms when the MC14448 Once detection smoke, this time
piezoelectric
buzzer
driving
circuit
to
start
oscillation,
start
to
be
able
to
output
to
maintain the high 160 ms after the cessation of ued during the detection
of smoke cessation of changes, at this time if not detected smoke beeper will not be
issued a warning sound.
In figure 3, the MC14468 1 pin joint PD1 pin of SCM when the ion chamber of
the ion current as the scene of smoke detection and change, voltage change generation
a
weak
side-spread
seized
15,
by
the
MC14468
internal
logic
processing
circuit
processing,
the
smoke
is
detected
by
1
pin-out
high
microcontroller
for
processing.
13-pin then slide rheostat is set to facilitate detection sensitivity when the led flashes
and the buzzer sounded a piercing sound of an audio alarm when the department has a
fire alarm signal-based.
In figure 3, the MC14468 1 pin joint PD1 pin of SCM when the ion chamber of
the ion current as the scene of smoke detection and change, voltage change generation

Collector potential with the smoke


Reduced light rate of 1% / ft


Reduced light rate of 4% / ft
Capacitor
0.6V
2.2V
5.5
±
0.3V
6PF