INTRODUCTION
The purpose of this project is to alert the
Bank manager in case unauthorized entry in to Bank strong room premises. This
system monitors the strong room of Bank and send text message to Bank manager
mobile number when an intrusion occurs. The motion sensor sense the strong room
condition and send signal to microcontroller. If an intrusion occurs in to the
strong room the alarm gives indication to the security staff and automatically
send text message to Bank manager.
GSM is also known as Global System for Mobile Communications,
or simply Global System for Mobile. A technology started development in 1985 by
a French company formerly known as Groupe Spécial Mobile. It's main competetor
is CDMA, currently in use by Bell Mobility, Telus Mobility and Mobility Canada
carriers.
The purpose of
this project is control any electrical device from your Cell Phone using SMS
and send SMS When a Human Intrusion occurs. With this circuit you can get the
sms alert. The main operation of the system is to detect the infrared signals
from the Human Beings will be detected by the PIR sensor then the GSM modem can
detect the signals and send the sms alert to the bank manager or
other authorized
peoples. The sensor will respond to a moving body only; it will not detect a
stationary infrared source, however it is very sensitive to changes in air
density close to the front of sensor and might produce false responses if not
covered by a lens or IR transparent window. The detection range without a lens
is about three feet but can be extended to up to 90 feet or more by placing an
infrared Fresnel lens in front of the sensor. A Glolab FL65 infrared Fresnel
lens with a focal length of 0.65 inch is recommended for longest range. The
lens can be mounted in an enclosure with its grooves facing inside, using
silicone rubber adhesive around the mounting flange.
When motion is detected the sensor will output a very small voltage
transition at pin 2. This voltage must be amplified many times in order to do
useful work. Two sections of a LP324 or equivalent quad operational amplifier
are used to provide the necessary amplification. Sensor pin 2 feeds into the
first stage amplifier IC1A at non-inverting input pin 3. This is a very high
impedance input and does not load the sensor. A high pass filter and feedback
network, R4, C4 connects from IC1A output pin 1 to inverting input pin 2 and a
high pass filter and bias network, C3, R3 connects from pin 2 to ground. These
networks set the amplifier gain and operating point and also form a bandpass
filter that amplifies only signals above DC and below about 10Hz. The
pyroelectric sensor is a thermal device and its response time falls within this
band of frequencies. Filtering out signals outside its response time eliminates
noise sources from frequencies that are not used anyway and makes the amplifier
more stable.
The output of the first amplifier stage, IC1A
is taken from pin 1. It then feeds through R5 and C5 into the inverting input
of the second amplifier stage at pin 13 of IC1B. C5 blocks the flow of DC and,
together with R5, forms a high pass filter to reduce gain at very low
frequencies. A feedback network R10, R11, C6 connects from IC1B output pin 14
to inverting input pin 13. R10 is a potentiometer that controls the amount of
feedback and therefore the gain of this stage. R11 limits the amount of
feedback. The non-inverting input to IC1B at pin 12 is biased to ½ of the
supply voltage or 2.5 volts by resistor divider network R6, R7, R8, R9. This
bias sets the operating point of the amplifier so that its output pin 14 is at
2.5 volts when no motion is being detected.
The output of IC1B pin 14 feeds into a window comparator made of IC1C
and IC1D. When an operational amplifier is used as a comparator It is run at
full open loop gain so that its output switches to a full up or down level when
one input is just a few millivolts higher or lower than the other. The purpose
of this comparator is to provide a small voltage window or dead zone centered
around 2.5 volts that will not respond to small voltage transitions caused by
noise or minor fluctuations from the sensor. The inverting input of IC1C at pin
9 is biased by the voltage at the junction of R6, R7 so it is about 175
millivolts above the 2.5 volt output level at pin 14 of IC1B, and inverting input
pin 10 of IC1C is connected to IC1B pin 14. IC1C will not turn on until pin 10
goes more positive than pin 9. The non-inverting input at pin 5 of IC1D is
biased by the voltage at the junction of R8, R9 to about 175 millivolts below
the 2.5 volt output level at pin 14 of IC1B, and inverting input pin 6 of IC1D
is connected to IC1B pin 14. IC1D will not turn on until pin 6 goes more
negative than pin 5.
BLOCK DIAGRAM
`
BLOCK DIGRAM EXPLANATION
The power supply unit
converts the 230 volts supply voltage to 9 volts and 12 volts. The 9 volt
supply is fed to bridge rectifier and it converts the 9v supply into 5v supply
for proper working of the system and it is fed to LM7805 which is a voltage
regulator which maintains a fixed output voltage.
The GSM modem
serves as the transmitter and receiver. There is a GSM Sim card inserted on the
module .It accepts the SMS and transfer the data to the microcontroller. The
GSM module also sends the status SMS from the system to the user.
The PIR sensor or the Passive
Infrared sensor is the part of the security system of the system .This sensor
detects the presence of human and alerts the user .The sensor is connected to
the microcontroller and the activation and deactivation of the sensor is
according to the SMS from the user.
The microcontroller is the
primary part of the system. It is programmed to analyze the incoming SMS and to
execute according to the information. The micro controller first checks the SMS
and analyze whether the SMS is from the default number, if only the SMS will be
executed. The output ports of the microcontroller are connected to the display
and to the relay driver circuit which controls the devices. The microcontroller
replies the status of the devices to the GSM module which sends it to the user.
The
display is an LCD display which displays the status of the devices which is
controlled by the system .The LCD is connected to one of the output ports of
the microcontroller .If the sensor
section is more effective and
this can take IR signals from the
human and send a high response to
the microcontroller .This signal
will enable gsm modem and send
sms to predefined mobile numbers at the same time the controller provide
an alarm signal to the buzzer
Microcontroller
T
Motion Sensor
A Passive Infrared sensor
(PIR sensor) is an electronic device that measures infrared (IR) light
radiating from objects in its field of view. PIR sensors are often used in the
construction of PIR-based motion detectors. Apparent motion is detected when an
infrared source with one temperature, such as a human, passes in front of an
infrared source with another temperature, such as a wall. A few mechanisms have
been used to focus the distant infrared energy onto the sensor surface. The
window may have multiple Fresnel lenses molded into it. This filtering window
may be used to limit the wavelengths to 8-14 micrometers which is closest to
the infrared radiation emitted by humans (9.4 micrometers being the strongest).
Keys
The keys are used to operate the module.
LCD
This is a basic 16
character by 2 line display. Black text on Green background. Utilizes the
extremely common HD44780 parallel interface chip set. It will need minimum 6
general I/O pins to interface to this LCD screen. Includes LED back light. This
will work in 4 bit and 8 bit mode.
Power
supply
TIn
mains-supplied electronic systems the AC input voltage must be converted into a
DC voltage with the right value and degree of stabilization. The ac from the
transformer secondary is rectified by a bridge rectifier and filtered by the
capacitor. A Linear voltage regulators produce regulated output voltage.
GSM Modem
A GSM modem is a
specialized type of modem which accepts a SIM card, and operates over a
subscription to a mobile operator, just like a mobile phone. When a GSM modem
is connected to a microcontroller, this allows the microcontroller to use the
GSM modem to communicate over the mobile network. While these GSM modems are
most frequently used to sending and receiving
SMS.
Alarm
Which is used to indicate when an
intrusion occurs by buzzer or Hooter.
PIR Sensor
Pyroelectric devices, such as the PIR sensor, have
elements made of a crystalline material that generates an electric charge when
exposed to infrared radiation. The changes in the amount of infrared striking
the element change the voltages generated, which are measured by an on-board
amplifier. The device contains a special filter called a Fresnel lens, which
focuses the infrared signals onto the element. As the ambient infrared signals
change rapidly, the on-board amplifier trips the output to indicate motion.
CIRCUIT DIAGRAM
·
MAIN CIRCUIT BOARD
·
BUZZER
·
LCD DISPLAY
CIRCUIT
DESCRIPTION
Main board
section
Power supply
In main
supply in electronics circuit systems the AC input voltage must be converted
into a DC voltage with the right value and degree of stabilization. The AC from
the transformer secondary is rectified by a bridge rectifier and filtered by
the capacitor.
Fig:-Circuit
diagram of a voltage regulated power supply
The +5volt power supply is based on
the 7805voltege regulator IC. This IC contains all the circuitry needed to
accept any input voltage from 8 to 18 volts and produce a steady +5 volt
output, accurate to with in 5 %( 0.25volts). It also contains current limiting
circuitry and thermal overload protection. The 10µf and 0.01µf capacitors serve
to help keep the power supply output
voltage constants when load condition change. The electrolytic capacitor
smoothes out any long-term or low frequency variations. However, at high
frequencies this capacitor is not very efficient. Therefore, the 0.01µf is
included to bypass high –frequency changes.
Micro controller
The PICmicro
MCU family is based on a RISC architecture, RISC stands for Reduced Instruction
set computer. High performance is accomplished as a result of the Harvard
architecture, which has separate data and address busses and two separate
memory spaces. Single cycle instructions allow high speed code execution, and
single word instructions reduce the moment of program memory space required.
One of the features in the PICmicro architecture that makes it so powerful is
the use of register files. The register file concept means that all RAM
locations, peripherals and I/O ports are organized as a simple bank of
register.
Oscillator
circuit
The
function of an oscillator circuit is to provide an accurate and stable periodic
clock signal to a microcontroller. The frequency of this clock signal can range
from a few kilohertz to tens of megahertz and determines how quickly the
microcontroller executes its instructions. Most micro controllers include a
clock driver circuit which is designed to drive a quartz crystal into oscillation.
The clock driver circuitry built into the PICmicro family is very flexible and
allows for different potions. The clock circuitry consists of two capacitors
and a quartz crystal. The values of capacitor are determined by both the clock
speed and by the selection of a quartz crystal or ceramic resonator as the
clock source. Quartz crystals are typically mounted in a sealed metal case with
two wire leads protruding from the bottom. Sometimes crystals may have a third
ground lead soldered or welded to the top of the metal can. Grounding the pin
on the metal can helps to both stabilize the crystal, lessening the impact of
mechanical shock, as well as reduce RF emission.
Rest circuit
The only
component required to run a PICnicro is a pull-up resistor connected to the
MCLR/Vpp pin. A resistor and a push button switch make up an actual rest
circuit. When switch is pressed, it completes a low impedance connection from
the MCLR/Vpp pin to ground, forcing the pic micro into rest mode until MCLR is
brought high. During this time the oscillator will run and the I/O pins will be
held in the reset condition.
GSM MODEM CIRCUIT
GSM
differs from first generation wireless systems in that it uses digital
technology and time division multiple access transmission methods. Voice is
digitally encoded via a unique encoder, which emulates the characteristics of
human speech. This method of transmission permits a very efficient data
rate/information content ratio.
The
GSM module is the transmitter and the receiver of the system. The antenna in
the module receives the SMS from the sender and transfer the information to the
microcontroller the microcontroller reply with AT command to initiate the
module and the reply is send to the predefined number. Thus the information is
passed from the module to the Authorized person.
The
Subscriber Identity Module or the SIM should be inserted into the GSM module.
The module is a modem which acts as a mobile phone. It is connected to the port
B of the microcontroller and works on a 12 volt supply. The modem has several
input and output pins which is used to transmit and receive the data. It
modulates the data to be sent and demodulates the received data and transfers
it to the micro controller.
The MAX232 IC is used
before connecting the modem to the microcontroller. The MAX232 IC is an integrated circuit
that converts signals from an RS-232 serial port to signals
suitable for use in TTL
compatible digital logic circuits. The MAX232 is a dual driver/receiver and
typically converts the RX, TX, CTS and RTS signals.
LCD DISPLAY
A liquid crystal display is a thin, flat
display device made up of any number of color or monochrome pixels arrayed in
front of a light source or reflector. It is prized by engineers because it uses
very small amounts of electric power and is therefore suitable for use in
battery powered electronic devices. Each pixel of an LCD consists of a layer of
perpendicular molecules aligned between two transparent electrodes and two
polarizing filters, the axes of polarity of which are perpendicular to each
other with no liquid crystal between the polarizing crystals The surfaces of
the electrodes that are in contact with the liquid crystal material are treated
so as to align the liquid crystal molecules in a particular direction this
treatment typically consists of a thin polymer layer that is unidirectional
rubbed using a cloth. Before applying the electric field, the orientation of
the liquid crystal molecules is determined by the alignment at the surfaces.
The LCD display displays the status of the devices connected to the
system. The display is connected to the port B of the microcontroller. The
display gives the information about whether the devices are on or off. The
display is updated with the current information from the microcontroller as the
SMS changes the status of the device.
BUZZER CIRCUIT
It most
commonly consists of a number of switches or sensors connected to a control
unit that determines if and which button was pushed or a preset time has
lapsed, and usually illuminates a light on the appropriate button or control
panel, and sounds a warning in the form of a continuous or intermittent buzzing
or beeping sound.
The buzzer is
associated with the security system. The PIR sensor senses the presence of
human and sends a signal to the buzzer and the micro controller. The buzzer
circuit is closed and it stars buzzing. At this moment itself the GSM module
sends an SMS to the user about the presence of human. The buzzer is only shut
off by the predefined user.
WORKING OF THE CIRCUIT
The main element of this project is
PIC 16F873A. PIC is a family of Harvard architecture microcontrollers
made by Microchip Technology, derived from the
PIC1640[1]
originally developed by General Instrument's Microelectronics Division.
The name PIC initially referred to "Peripheral Interface Controller”. The PIC controls the entire
system .Mainly the system has two sections, the security unit and the
automation unit. The microcontroller is programmed to execute the SMS from the
predefined number and to take action according to the content in the message.
SMS other users are also received by the GSM module but the message from the
predefined number is only executed.
The antenna in the GSM modem receives
the SMS.The modem us connected to the port A of the microcontroller .The micro
controller checks the mobile number and the format of the message. If the
message is from the right number and is in the right format, the content in the
message is executed. If the message is to switch on a device, the relay
associated with the device is triggered by the microcontroller.
The PIR sensor
of the system are connected to the port B and port C respectively. The PIR
sensor detects the presence of human and will send an SMS to the user as ‘Human
Detected’ as in the program. The PIR sensor can be activated or deactivated by
sending an SMS. The sensor is connected to the buzzer which alerts the user
about the human intrusion.
The power for
the working is supplied from the power supply unit of the system. The output
from the transformer is supplied to the bridge rectifier and then to the
voltage regulator to give regulated power supply to the system. The GSM module
works on the 12volt supply and the PIC on 5 volts.
COMPONENTS DESCRIPTION
MICROCONTROLLER DESCRIPTION
The name PIC initially referred to "Programmable Interface Controller”. PIC is a family of Harvard architecture microcontrollers made
by Microchip Technology, derived from the PIC1640 originally developed by General Instrument's Microelectronics Division. PICs are popular with both
industrial developers and hobbyists alike due to their low cost, wide
availability, large user base, extensive collection of application notes,
availability of low cost or free development tools, and serial programming (and
re-programming with flash memory) capability. Devices called "programmers" are traditionally used to get program code into the
target PIC. Most PICs that Microchip currently sell feature ICSP (In Circuit Serial Programming) and/or LVP (Low Voltage Programming) capabilities, allowing the PIC
to be programmed while it is sitting in the target circuit. ICSP programming is performed using two pins, clock and
data, while a high voltage (12V) is present on the Vpp/MCLR pin. Low voltage
programming dispenses with the high voltage, but reserves exclusive use of an
I/O pin and can therefore be disabled to recover the pin for other uses (once
disabled it can only be re-enabled using high voltage programming).
PIC16F873A/876A
devices are available only in 28-pin packages, while PIC16F874A/877A devices
are available in 40-pin and 44-pin packages. All devices in the PIC16F87XA
family share common architecture with the following differences: • The
PIC16F873A and PIC16F874A have one-half of the total on-chip memory of the
PIC16F876A and PIC16F877A • The 28-pin devices have three I/O ports, while the
40/44-pin devices have five • The 28-pin devices have fourteen interrupts,
while the 40/44-pin devices have fifteen • The 28-pin devices have five A/D
input channels, while the 40/44-pin devices have eight • The Parallel Slave
Port is implemented only on the 40/44-pin devices.
Fig:-PIC 16F873A Fig:-Pin details
Why
we use the PIC 16F873A
1.
Code Efficiency
The PIC is an 8 bit
Microcontroller based on the Harvard architecture – which means there are
separate internal busses for memory and data. The throughput rate is therefore
increased due to simultaneous access to both data and program memory.
Conventional Microcontrollers tend to have one internal bus handling both data
and program. This slows operation down by at least a factor of 2 when compared
to the PICMCU.
2. Instruction
Set
There are 35 instructions you
have to learn in order to write software for midrange families. Each
instruction, with the exception of CALL, GOTO or bit testing instructions
(BTFSS, INCFSZ), executes in one cycle.
3. Speed
The PIC has an internal
divide by 4 connected between the oscillator and the internal clock bus. This
makes instruction time easy to calculate,especially if you use a 4 MHz crystal.
Each instruction cycle then works out at 1uS. The PIC is a very fast micro to
work with e.g. a 20MHz crystal steps through a program at 5 million
instructions per second
4. Static
operation
The PIC is a fully static
Microcontroller; in other words, if you stop the clock, all the register
contends are maintained. In practice you would not actually do this, you would
place the PIC into a Sleep mode – this stops the clock and sets up various
flags within the PIC to allow you to know what state it was in before the
Sleep. In Sleep, the PIC takes only its standby current which can be less the
1uA.
5. Drive
capability
The PIC has a high output
drive capability and can directly drive LEDs and triacs etc. Any I/O pin can
sink/source 25mA
6. Options
A range of speed,
temperature, package, I/O lines, timer functions,serial communication, A/D and
memory sizes is available from the PIC family to suit virtually all your
requirements.
7. Versatility
The PIC is a versatile micro and in volume is a low cost solution to
replace even a few logic gates; especially where space is at a premium.
8.
Security
The PICmicro MCU has a code
protection facility which is one of the best in the industry. Once the
protection bit has been programmed, the contents of the program memory cannot
be read out in a way that the program code can be reconstructed.
Special
Microcontroller Features:
Ø 100,000
erase/write cycle Enhanced Flash program memory typical
Ø 1,000,000
erase/write cycle Data EEPROM memory typical
Ø Data
EEPROM Retention > 40 years
Ø Self-reprogrammable
under software control
Ø In-Circuit
Serial Programming™ (ICSP™) via two pins
Ø Watchdog
Timer (WDT) with its own on-chip RC oscillator for reliable operation
Ø Programmable
code protection
Ø Power
saving Sleep mode
Ø Selectable
oscillator options
Ø In-Circuit
Debug (ICD) via two pins
CMOS Technology:
Ø
Low-power, high-speed Flash/EEPROM technology
Ø
Fully static design
Ø
Wide operating voltage range (2.0V to 5.5V)
Ø
Commercial and Industrial temperature ranges
Ø
Low-power consumption
Ports
There are five
parallel ports in the PIC 16F877A, labeled A–E. All pins can be used as bit- or
byte oriented digital input or output. It can be seen that many of the port
pins have two or more functions, depending on the initialization of the
relevant control registers. The TRIS (data direction) register bits in bank 1
is used set the port as input or output. However, there is an IMPORTANT
exception. Ports A and E are set to ANALOG INPUT by default, because the
analogue control register ADCON1 in bank 1. If analog input is required only on
selected pins, ADCON1 can be initialized with bit codes that give a mixture of
analogue and digital I/O on Ports A and E.
PORTA and the TRISA Register
PORTA is a
6-bit wide, bidirectional port. The corresponding data direction register is
TRISA. Setting a TRISA bit (= 1) will make the corresponding PORTA pin an input
(i.e., put the corresponding output driver in a High-Impedance mode). Clearing
a TRISA bit (= 0) will make the corresponding PORTA pin an output (i.e., put the
contents of the output latch on the selected pin).Reading the PORTA register
reads the status of the pins, whereas writing to it will write to the port
latch. All write operations are read-modify-write operations .Therefore, a
write to a port implies that the port pins are read, the value is modified and
then written to the port data latch. Pin RA4 is multiplexed with the Timer0
module clock input to become the RA4/T0CKI pin. The RA4/T0CKIpin is a Schmitt
Trigger input and an open-drain output. All other PORTA pins have TTL input
levels and full CMOS output drivers.
PORTB and the TRISB Register
PORTB is an
8-bit wide, bidirectional port. The corresponding data direction register is
TRISB. Setting a TRISB bit (= 1) will make the corresponding PORTB pin an input
(i.e., put the corresponding output driver in a High-Impedance mode). Clearing
a TRISB bit (= 0) will make the corresponding PORTB pin an output (i.e., put the
contents of the output latch on the selected pin). Three pins of PORTB are
multiplexed with the In-Circuit Debugger and Low-Voltage Programming function:
RB3/PGM, RB6/PGC and RB7/PGD. The alternate functions of these pins are
described in Section 14.0 “Special Features of the CPU”. Each of
the PORTB pins has a weak internal pull-up. A single control bit can
turn on all the pull-ups. This is performed by clearing bit RBPU
(OPTION_REG<7>). The weak pull-up is automatically turned off when
the port pin is configured as an output. The pull-ups are disabled on a
power-on-reset.
PORTC and the TRISC Register
PORTC is an
8-bit wide, bidirectional port. The corresponding data direction register is
TRISC. Setting a TRISC bit (= 1) will make the corresponding PORTC pin an input
(i.e., put the corresponding output driver in a High-Impedance mode). Clearing
a TRISC bit (= 0) will make the corresponding PORTC pin an output (i.e., put
the contents of the output latch on the selected pin). PORTC is multiplexed
with several peripheral functions (Table 4-5). PORTC pins have Schmitt Trigger
input buffers. When the I2C module is enabled, the PORTC<4:3> pins can be
configured with normal I2C levels, or with SMBus levels, by using the CKE bit
(SSPSTAT<6>). When enabling peripheral functions, care should be taken in
defining TRIS bits for each PORTC pin. Some peripherals override the TRIS bit
to make a pin an output, while other peripherals override the TRIS bit to make
a pin an input. Since the TRIS bit override is in effect while the peripheral
is enabled, read-modify write instructions (BSF, BCF, and XORWF) with TRISC as
the destination, should be avoided. The user should refer to the corresponding
peripheral section for the correct TRIS bit settings.
PORTD and TRISD Registers
PORTD is an
8-bit port with Schmitt Trigger input buffers. Each pin is individually
configurable as an input or output. PORTD can be configured as an 8-bit wide microprocessor
port (Parallel Slave Port
PORTE and TRISE Register
PORTE has
three pins (RE0/RD/AN5, RE1/WR/AN6 and RE2/CS/AN7) which are individually
configurable as inputs or outputs. These pins have Schmitt Trigger input
buffers. The PORTE pins become the I/O control inputs for the microprocessor
port when bit PSPMODE (TRISE<4>) is set. In this mode, the user must make
certain that the TRISE<2:0> bits are set and that the pins are configured
as digital inputs. Also, ensure that ADCON1 is configured for digital I/O. In
this mode, the input buffers are TTL. Register 4-1 shows the TRISE register
which also controls the Parallel
Slave Port
TIMER0 MODULE
The Timer0 module timer/counter
has the following features:
Ø
8-bit
timer/counter
Ø
Readable and writable
Ø
8-bit software programmable prescaler
Ø
Internal or external clock select
Ø
Interrupt on overflow from FFh to 00h
Ø
Edge select for external clock
Timer mode is
selected by clearing bit T0CS (OPTION_REG<5>). In Timer mode, the Timer0 module
will increment every instruction cycle (without prescaler). If the TMR0
register is written, the increment is inhibited for the following two
instruction cycles. The user can work around this by writing an adjusted value
to the TMR0 register. Counter mode is selected by setting bit T0CS (OPTION_REG<5>).
In Counter mode, Timer0 will increment either on every rising or falling edge
of pin RA4/T0CKI. The incrementing edge is determined by the Timer0 Source Edge
Select bit, T0SE (OPTION_REG<4>). Clearing bit T0SE selects the rising edge.
Timer0 Interrupt
The TMR0
interrupt is generated when the TMR0 register overflows from FFh to 00h. This
overflow sets bit TMR0IF (INTCON<2>). The interrupt can be masked by
clearing bit TMR0IE (INTCON<5>). Bit TMR0IF must be cleared in software
by the Timer0 module Interrupt Service Routine before re-enabling this
interrupt. The TMR0 interrupt cannot awaken the processor from Sleep since the
timer is shut-off during Sleep.
TIMER1 MODULE
The Timer1
module is a 16-bit timer/counter consisting of two 8-bit registers (TMR1H and
TMR1L) which are readable and writable. The TMR1 register pair (TMR1H:TMR1L)
increments from 0000h to FFFFh and rolls over to 0000h. The TMR1 interrupt, if
enabled, is generated on overflow which is latched in interrupt flag bit,
TMR1IF (PIR1<0>). This interrupt can be enabled/disabled by
setting/clearing TMR1 interrupt enable bit, TMR1IE (PIE1<0>).
Timer1 can operate in one of
two modes:
Ø
As a Timer
Ø
As a Counter
The operating mode is
determined by the clock select bit, TMR1CS (T1CON<1>). In Timer mode,
Timer1 increments every instruction cycle. In Counter mode, it increments on
every rising edge of the external clock input. Timer1 can be enabled/disabled
by setting/clearing control bit, TMR1ON (T1CON<0>). Timer1 also has an
internal “Reset input”. This Reset can be generated by either of the two CCP
modules.
TIMER2 MODULE
Timer2 is an
8-bit timer with a prescaler and a postscaler. It can be used as the PWM time
base for the PWM mode of the CCP module(s). The TMR2 register is readable and
writable and is cleared on any device Reset. The input clock (FOSC/4) has a
presale option of 1:1, 1:4 or 1:16, selected by control bits T2CKPS1:T2CKPS0
(T2CON<1:0>). The Timer2 module has an 8-bit period register, PR2. Timer2
increments from 00h until it match PR2 and then resets to 00h on the next
increment cycle. PR2 is a readable and writable register. The PR2 register is initialized
to FFh upon Reset. The match output of TMR2 goes through a 4-bit postscaler
(which gives a 1:1 to 1:16 scaling inclusive) to generate a TMR2 interrupt
(latched in flag bit, TMR2IF (PIR1<1>)). Timer2 can be shut-off by
clearing control bit, TMR2ON (T2CON<2>), to minimize power consumption.
PIC instruction set
MASTER
SYNCHRONOUS SERIAL PORT (MSSP) MODULE
Overview
The Master
Synchronous Serial Port (MSSP) module is a serial interface, useful for
communicating with other peripheral or microcontroller devices. These
peripheral devices may be serial EEPROMs, shift registers, display drivers, A/D
converters, etc. The MSSP module can operate in one of two modes:
Ø
Serial Peripheral Interface (SPI)
Ø
Inter-Integrated Circuit (I2C)
- Full Master mode
- Slave mode (with general
address call)
The I2C interface supports the
following modes in hardware:
Ø
Master mode
Ø
Multi-Master mode
Ø
Slave mode
SPI Mode
The SPI mode allows 8 bits of data to be synchronously transmitted and
received simultaneously. All four modes of SPI are supported. To accomplish communication,
typically three pins are used:
Ø
Serial Data Out (SDO) – RC5/SDO
Ø
Serial Data In (SDI) – RC4/SDI/SDA
Ø
Serial Clock (SCK) – RC3/SCK/SCL
Additionally, a fourth pin
may be used when in a Slave mode of operation:
Ø
Slave Select (SS) – RA5/AN4
When initializing the SPI,
several options need to be specified. This is done by programming the
appropriate control bits (SSPCON<5:0> and SSPSTAT<7:6>).
These control bits allow the
following to be specified:
Ø
Master mode (SCK is the clock output)
Ø
Slave mode (SCK is the clock input)
Ø
Clock Polarity (Idle state of SCK)
Ø
Data Input Sample Phase (middle or end of data output
time)
Ø
Clock Edge (output data on rising/falling edge
of SCK)
Ø
Clock Rate (Master mode only)
Ø
Slave Select mode (Slave mode only)
I2C Mode
The MSSP
module in I2C mode fully implements all master and slave functions (including
general call support) and provides interrupts on Start and Stop bits in hardware
to determine a free bus (multi-master function). The MSSP module implements the
standard mode specifications, as well as 7-bit and 10-bit addressing.
MSSP BLOCK DIAGRAM
(I2C
MODE)
Two pins are used for data transfer:
Ø
Serial clock (SCL) – RC3/SCK/SCL
Ø
Serial data (SDA) – RC4/SDI/SDA
The user must configure these
pins as inputs or outputs through the TRISC<4:3> bits.
The MSSP module has six registers for I2C operation.
These are:
Ø
MSSP Control Register (SSPCON)
Ø
MSSP Control Register 2 (SSPCON2)
Ø
MSSP Status Register (SSPSTAT)
Ø
Serial Receive/Transmit Buffer Register (SSPBUF)
Ø
MSSP Shift Register (SSPSR) – Not directly accessible
Ø
MSSP Address Register (SSPADD)
SLAVE MODE
In Slave mode, the SCL and SDA pins must be configured as inputs
(TRISC<4:3> set). The MSSP module will override the input state with the
output data when required (slave-transmitter). The I2C Slave mode hardware will
always generate an interrupt on an address match. Through the mode select bits,
the user can also choose to interrupt on Start and Stop bits when an address is
matched, or the data transfer after an address match is received, the hardware
automatically will generate the Acknowledge (ACK) pulse and load the SSPBUF
register with the received value currently in the SSPSR register. Any
combination of the following conditions will cause the MSSP module not to give
this ACK pulse:
Ø
The buffer full bit, BF (SSPSTAT<0>), was
set before the transfer was received.
Ø
The overflow bit, SSPOV (SSPCON<6>), was
set before the transfer was received.
UNIVERSALSYNCHRONOUSASYNCHRONOUS
RECEIVERTRANSMITTER (USART)
The Universal
Synchronous Asynchronous Receiver Transmitter (USART) module is one of the two
serial I/O modules. (USART is also known as a Serial Communications Interface
or SCI.) The USART can be configured as a full-duplex asynchronous system that can
communicate with peripheral devices, such as CRT terminals and personal
computers, or it can be configured as a half-duplex synchronous system that can
communicate with peripheral devices, such as A/D or D/A integrated circuits,
serial EEPROMs, etc.
The USART can be configured in the following modes:
Ø
Asynchronous (full-duplex)
Ø
Synchronous – Master (half-duplex)
Ø Synchronous
– Slave (half-duplex)
TXSTA: TRANSMIT STATUS AND CONTROL REGISTER
(ADDRESS 98h)
Bit 7 CSRC: Clock Source
Select bit
Asynchronous mode: Don’t
care.
Synchronous mode:
1 = Master mode (clock
generated internally from BRG)
0 = Slave mode (clock from
external source)
Bit 6 TX9: 9-bit
Transmit Enable bit
1 = Selects 9-bit transmission
0 = Selects 8-bit transmission
Bit 5 TXEN: Transmit
Enable bit
1 = Transmit enabled
0 = Transmit disabled
Note: SREN/CREN
overrides TXEN in Sync mode.
Bit 4 SYNC: USART Mode
Select bit
1 = Synchronous mode
0 = Asynchronous mode
Bit 3 Unimplemented: Read
as ‘0’
Bit 2 BRGH: High Baud
Rate Select bit
Asynchronous mode:
1 = High speed
0 = Low speed
Synchronous mode:
Unused in this mode.
Bit 1 TRMT: Transmit
Shift Register Status bit
1 = TSR empty
0 = TSR full
Bit 0 TX9D: 9th bit of
Transmit Data, can be Parity bit
ANALOG-TO-DIGITAL
CONVERTER (A/D) MODULE
The Analog-to-Digital (A/D) Converter module has five inputs for the
28-pin devices and eight for the 40/44-pin devices. The conversion of an analog
input signal results in a corresponding 10-bit digital number. The A/D module has
high and low-voltage reference input that is software selectable to some
combination of VDD, VSS, RA2 or RA3. The A/D converter has a unique feature of
being able to operate while the device is in Sleep mode. To operate in Sleep,
the A/D clock must be derived from the A/D’s internal RC oscillator.
The A/D module
has four registers. These registers are:
Ø
A/D Result High Register (ADRESH)
Ø
A/D
Result Low Register (ADRESL)
Ø
A/D Control Register 0 (ADCON0)
Ø A/D
Control Register 1 (ADCON1)
Block diagram
MEMORY ORGANIZATION
There are three memory blocks in each
of thePIC16F87XA devices. The program memory and data memory have separate
buses so that concurrent access can occur and is detailed in this section. The
PIC16F876A/877A devices have 8K words x 14 bits of Flash program memory, while
PIC16F873A/874A devices have 4K words x 14 bits. Accessing a location above the
physically implemented address will cause a wrap around .The Reset vector is at
0000h and the interrupt vector is at 0004h.
PIC16F876A/877APROGRAM MEMORY MAP AND STACK
Data Memory
Organization
The data memory is partitioned into
four banks which contain the General Purpose Registers and the Special Function
Registers. Each bank extends up to 7Fh (128 bytes). The lower locations of each
bank are reserved for the Special Function Registers. Above the Special
Function Registers are General Purpose Registers, implemented as static RAM.
All implemented banks contain Special Function Registers. Some frequently used
Special Function Registers from one bank may be mirrored in another bank for
code reduction and quicker access.
Chip Configuration
Word
This sets up aspects of the chip
operation which cannot be sub-sequently changed without reprogramming. A
special area of program memory outside the normal range (address 2007h) stores
a chip configuration word; the clock type, and other MCU options are set by
loading the configuration bits with a suitable binary code
1. Code protection
Normally, the program machine code
can be read back to the programming host computer, be disassembled and the
original source program recovered. This can be prevented if commercial or
security considerations require it.
2. In-Circuit Debugging
In-circuit debugging (ICD) allows the
program to be downloaded after the chip has been fitted in the application circuit,
and allows it to be tested with the real hardware. With ICD, the chip can be
programmed, and reprogrammed during debugging, while avoiding possible
electrical and mechanical damage caused by removal from the circuit.
3. Low voltage programming
Normally, when the chip is
programmed, a high voltage (12–14 V) is applied to the MCLR pin. To avoid the
need to supply this voltage during in-circuit programming (e.g. during remote
reprogramming), a low-voltage programming mode is available; however, option means that RB3 is not then available
for general I/O functions during normal operation.
4 .Power-up timer
When
the supply power is applied to the programmed MCU, the start of program
execution should be delayed until the power supply and clock are stable,
other-wise the program may not run correctly. The power-up timer may therefore
be enabled as a matter of routine. It avoids the need to reset the MCU manually
at start up, or connect an external reset circuit, as is necessary with some
microprocessors. An internal oscillator provides a delay between the power
coming on and an internal MCU reset of about 72 ms. this is followed by an
oscillator start up delay of 1024 cycles of the clock before program execution
starts. At a clock frequency of 4 MHz, this works out to 256 μs.
5. Brown-out reset
Brown out refers to a short dip in
the power-supply voltage, caused by mains supply fluctuation, or some other
supply fault, which might interrupt the program execution. If the Brown- Out
Detect Enable bit (BODEN) is set, a PSU glitch will cause the device to be held
in reset until the supply recovers, and then wait for the power-up timer to
time out, before restarting.
6. Watchdog timer
The watchdog timer is designed to
automatically reset the MCU if the programmable functions, by stopping or
getting stuck in loop. This could be caused by an undetected bug in the
program, an unplanned sequence of inputs or supply fault. A separate internal
oscillator and counter automatically generate a reset, unless this is disabled
in the configuration word. If the watchdog timer is enabled, it should be
regularly reset by an instruction in the program loop (CLRWDT) to prevent the
reset. If the program hangs, and the watchdog timer reset instruction not
executed, the MCU will restart.
7. RC oscillator
The MCU clock drives the program
along, providing the timing signals for program execution. The RC
(resistor–capacitor) clock is cheap and cheerful, requiring only these two
external components, operating with the internal clock driver circuit, to
generate the clock. The time constant (product of R & C) determines the
clock period. A variable resistor cans be used to give a manually adjustable
frequency, although it is not very stable or accurate.
8. Crystal oscillator
If greater precision is required,
especially if the program uses the hardware timers to make accurate
measurements or generate precise output signals, a crystal (XTAL) oscillator is
needed .Normally, it is connected across the clock pins with a pair of small
capacitors (15 pF) to stabilize the frequency. A convenient value is 4 MHz;
this gives an instruction cycle time of 1μs. This is also the maximum frequency
allowed for the XT configuration setting. The PIC 16FXXXA series MCU generally
run at a maximum clock rate of 20 MHz, using a high-speed (HS) crystal which
requires the selection of the HS configuration option.
PIR
Sensor
The
PIR (Passive Infra-Red) Sensor is a pyro electric device that detects motion by
measuring changes in the infrared levels emitted by surrounding objects. This
motion can be detected by checking for a high signal on a single I/O pin.
THEORY
OF OPERATION
Pyro
electric devices, such as the PIR sensor, have elements made of a crystalline
material that generates an electric charge when exposed to infrared radiation.
The changes in the amount of infrared striking the element change the voltages
generated, which are measured by an on-board amplifier. The device contains a
special filter called a Fresnel lens, which focuses the infrared signals onto
the element. As the ambient infrared signals change rapidly, the on-board
amplifier trips the output to indicate motion
Features
·
Single bit output
·
Small size makes it easy to conceal
·
Compatible with all Parallax microcontrollers
Application
·
Alarm
Systems
·
Halloween
Props
·
Robotics
Pin Definitions and Ratings
Pin Name
Function
- GND
Connects to
Ground or Vss
+
V+ Connects
to +5 VDC or Vdd
OUT Output
Connects to an I/O
pin set to INPUT mode
GSM/GPRS
Modem TTL (5V)
GSM/GPRS
Modem-TTL (5V) from rhydo LABZ is built with Tri-band GSM/GPRS engine, works on
frequencies EGSM 900 MHz, DCS 1800 MHz and PCS 1900 MHz. It is very compact in
size and easy to use as plug in module. The Modem is coming with 5V TTL
interface, which allows you to connect directly to 5V microcontroller/Arduino.
The baud rate is configurable from 9600- 115200 through AT command. The
GSM/GPRS TTL Modem is having internal TCP/IP stack to enable you to connect
with internet via GPRS. It is suitable for SMS as well as DATA transfer
application in M2M interface.
FEATURES
·
High Quality Product (Not hobby grade)
·
Plug and Play Module
·
Tri-Band GSM/GPRS 900/ 1800/ 1900 MHz
·
5V TTL interface for direct connection with
MCU/Arduino
·
Configurable baud rate
·
SMA connector with GSM Antenna.
·
Built in SIM Card holder.
·
Built in Network Status LED
·
Inbuilt Powerful TCP/IP protocol stack for internet
data transfer over GPRS.
·
Standard 2.54mm Connector Pitch
·
Switch ON/OFF Pin at connector
·
Status LED Pin at connector
·
Hardware Flow controlling pins available at
connector
SPECIFICATIONS
·
Tri-Band GSM/GPRS 900/ 1800/ 1900 MHz
·
GPRS multi-slot class 10
·
Compliant to GSM phase 2/2+
·
Class 4 (2W@ 900 MHz)
·
Class 1 (1W@ 1800/1900MHz)
·
Built in Powerful TCP/IP
·
Data Specifications
·
GPRS Class 10 - max 85.6 kbps (downlink)
·
Coding scheme 1, 2, 3, 4
·
CSD up to 14.4 kbps
·
PPP Stack
·
Non transparent mode
·
Normal operation temperature: -20 °C to +55 °C
·
LCD display
Internal block
diagram of LCD display
INTERFACE PIN CONNECTIONS
SEVEN DARLINGTON ARRAYS
The ULN2001A, ULN2002A, ULN2003 and
ULN2004Aare high voltage, high current darling ton arrays each containing seven
open collector darling ton pairs with common emitters. Each channel rated at
500mAand can withstand peak currents of 600mA.Suppressiondiodesare included for
inductive load driving and the inputs are pinned opposite the outputs to
simplify board layout. The four versions interface to all common logic
families.
These versatile devices are useful for driving a wide range
of loads including solenoids, relays DC motors; LED displays filament lamps,
thermal print heads and high power buffers. The ULN2001A/2002A/2003Aand
2004Aare supplied in 16 pin plastic DIP packages with a copper lead frame to
reduce thermal resistance.
CRYSTAL OSCILLATOR
A crystal oscillator is an
electronic circuit that uses the mechanical resonance of a vibrating crystal of
piezoelectric material to create an electrical signal with a very precise
frequency. This frequency is commonly used to keep track of time (as in quartz
wristwatches), to provide a stable clock signal for digital integrated
circuits, and to stabilize frequencies for radio transmitters and receivers.
The most common type of piezoelectric resonator used is the quartz crystal, so
oscillator circuits designed around them were called "crystal
oscillators".
Fig: - CRYSTAL OSCILLATOR
OPERATION
A crystal is a solid in which the
constituent atoms, molecules, or ions are packed in a regularly ordered,
repeating pattern extending in all three spatial dimensions.Almost any object
made of an elastic material could be used like a crystal, with appropriate
transducers, since all objects have natural resonant frequencies of vibration.
For example, steel is very elastic and has a high speed of sound. It was often
used in mechanical filters before quartz.
COMMONLY
USED CRYSTAL FREQUENCIES
to low cost since
they are used for television color receivers. Using frequency dividers,
frequency multipliers and phase locked loop circuits, it is practical to derive
a wide range of frequencies from one reference frequency.
BUZZER
It most commonly consists of a number
of switches or sensors connected to a control unit that determines if and which
button was pushed or a preset time has lapsed, and usually illuminates a light
on the appropriate button or control panel, and sounds a warning in the form of
a continuous or intermittent buzzing or beeping sound.
POWER SUPPLY
For the proper operation of a circuit a power supply has a
main role. The power supply converts AC main supply to regulated DC voltage. A
regulated DC power supply refers to the circuit whose output is constant DC
voltage which will not change its value when there is a change in the AC main
voltage and the load. The detailed block diagram and circuit of the 9v DC
regulated power supply.
The DC
regulated power supply consists of the following parts
Ø Step down transformer (9v)
Ø Rectifier circuit
Ø Regulator circuit
STEP DOWN TRANSFORMER
A transformer is a device that transfers electrical energy from
one circuit to another through inductively coupled conductors—the transformer's coils. A varying current in the first
or primary winding creates a varying magnetic flux in the
transformer's core, and thus a varying magnetic field through
the secondary winding. This varying magnetic field induces a varying electromotive force (EMF) or "voltage"
in the secondary winding.
The step
down transformer is used to reduce or step down the main AC voltage to a low
value AC supply. The transformer primary winding is connected to mains 230v, 50
Hz AC supply. The voltage across the secondary of this transformer is a 12v AC
voltage. The output from the The transformer is based on two principles:
firstly, that an electric current can produce a magnetic field
(electromagnetism) and secondly that a changing magnetic field within a coil of
wire induces a voltage across the ends of the coil (electromagnetic induction).
Changing the current in the primary coil changes the magnetic flux that is
developed. The changing magnetic flux induces a voltage in the secondary coil.
Current passing through
the primary coil creates a magnetic field. The primary and secondary coils are
wrapped around a core of very high magnetic permeability, such as iron, so that
most of the magnetic flux passes through both primary and secondary coils
Fig:-Step down transformer
RECTIFIER CIRCUIT
The rectifier circuit consists of a
full wave bridge rectifier circuit. The rectifier consists of a four diodes D1,
D2, D3andD4. IN this circuit, during the positive half cycle of the secondary
will forward bias the diodes D2and D4 and load to ground.
At this time the diodes D1and D3 is
in reverse biased and current does not flow through it. During the negative
half cycle of the secondary will forward bias the diodes D1and D2 and load to
ground. At this time the diodes D2and D4 is in reverse biased and current does
not flow through it.
REGULATOR CIRCUITS
The DC output from the filter circuit
changes according to change in the load values or according in the input AC
main supply. To keep this DC output constant irrespective of change in the
input AC main voltage and load, a circuit known as regulator circuit is used.
In this circuit, a voltage regulator IC 7805 is used to get a +5v regulated DC
output voltage.
The7805 is a three pin IC
used for voltage regulation at 5v. The first pin of the IC is its input
terminal to which unregulated DC voltage is applied. The second pin is its
ground terminal and unregulated +5v DC voltage is
obtained across the third terminal with respect to the ground. The regulator is
the last stage in the power supply.
COMPONENTS LIST
Sl no
|
components
|
specifications
|
quantity
|
1
|
Microcontroller
|
16F877A
|
1
|
2
|
Bridge
rectifier
|
MICW10M
|
1
|
3
|
Regulator
IC
|
LM7805
|
1
|
4
|
Transformer
|
0-230V/0-15
500Ma
|
1
|
5
|
4MHz
|
1
|
|
6
|
Electrolytic
capacitor
|
1000µf50v
|
1
|
10µf16v,4.7µf63v
|
1
|
||
7
|
Disk
capacitor
|
.1µf
|
1
|
22pf
|
2
|
||
8
|
Resistor
|
220E
|
2
|
10K
|
4
|
||
100E
|
3
|
||
2.2K,3.9K,56E,1.5K
|
1
|
||
9
|
LED
|
5mm
|
4
|
10
|
IR sensor
|
TSOP1738
|
2
|
11
|
Motor
|
L293DD
|
2
|
12
|
Buzzer
|
1
|
|
13
|
LCD Display
|
1
|
SOFTWARE DISCRIPTION
MPLAB IDE
MPLAB Integrated Development
Environment (IDE), integrated tool set for the development of embedded
applications employing Microchip's PIC® and dsPIC® microcontrollers. MPLAB IDE
runs as a32-bit application on MS Windows®, is easy to use and includes a host
of free software components for fast application development and super- charged
debugging. MPLAB IDE also serves as a single, unified graphical user interface
for additional Microchip and third party software graphical user interface for
additional Microchip and third party
software and hardware development tools. A development system
for embedded controllers is a system of program running on desktop pc to help
write, read, debug and program code the intelligence of embedded system
applications into a microcontroller. MPLAB IDE runs on a pc and contains
all the components needed to debug and depoly embedded system applications.
MPLAB IDE
programmer‟s editor helps write correct code
with language tools of choice. The editor is aware of the assembler and
compiler programming constructs and automatically colors-keys‟‟ the source code to help ensure it is syntactically correct.
The project manager enables you to organize the various files used in your
applications: source files, processor description header files and library
files. When the code built, you can control how rigorously code will be
optimized for size or speed by compiler and where individual variables and
program data will be programmed into the device.
The MPLAB Editor
is an integrated part of the MPLAB IDE Integrated Development Environment. The
editor is always available when MPLAB IDE is running. The MPLAB IDE and MPLAB
Editor are designed to provide developers with an easy and quick method to
develop and debug firmware for Microchip Technology’s PIC micro microcontroller
(MCU) and ds PIC digital signal controller (DSC) product families
DESCRIPTION OF AN “EMBEDDED SYSTEM
An embedded system is typically a
design making use of the power of a small microcontroller, like the Microchip
PICmicro® MCU or dsPIC® Digital Signal Controller (DSCs). These
microcontrollers combine a microprocessor unit (like the CPU in a desktop PC)
with some additional circuits called “peripherals”, plus some additional
circuits on the same chip to make a small control module requiring few other
external devices. This single device can then be embedded into other electronic
and mechanical devices for low-cost digital control.
Fig:-PIC programmer
PROGRAM
MICROCONTROLLER PROGRAM
#include<16f73.h>
#include<string.h>
#fuses
HS,NOWDT,PUT,NOBROWNOUT//,NOLVP
#use
delay(clock=4M)
#define
PIR_Sensor PIN_C5
#define buzzer PIN_C4
#define
buzzer_on output_high(buzzer)
#define
buzzer_off output_low(buzzer)
int8 const
phno1[]="+919633896565";
//#rom 0x2100={00}
#define
device_stat_addr 0
int8
device_status,sms_no,buffer_string[25],PIR_flag,SMS_Flag;
#include"LCD_4bit.c"
#include"sim_300.c"
int8 check_sms()
{
output_toggle(PIN_A5);
sms_no++;
if(sms_no >5)
sms_no=1;
delay_ms(100);
if(get_sms(sms_no))
{
strcpy(buffer_string,phno1);
if(!strcmp(ph_number,buffer_string))
{
return 1;
}
}
return 0;
}
void test_signal()
{
int8 strength;
lcd_send_cmd(lcd_clear);
while(TRUE)
{
output_toggle(PIN_A5);
//sync();
delay_ms(2000);
strength=read_strength();
if(strength>31)
strength=0;
lcd_goto(1,1);
lcd_send_byte(CUST_CHAR_1);
if(strength==0)
lcd_send_byte(' ');
else if(strength<6)
lcd_send_byte(CUST_CHAR_2);
else if(strength<15)
lcd_send_byte(CUST_CHAR_3);
else if(strength<18)
lcd_send_byte(CUST_CHAR_4);
else if(strength<24)
lcd_send_byte(CUST_CHAR_5);
else
lcd_send_byte(CUST_CHAR_6);
lcd_goto(2,1);
printf(lcd_send_byte,"%03u",strength);
//
// for(strength=0;strength<5;strength++)
//
printf(lcd_send_byte,"%2X,",ph_number[strength]);
}
}
void init_ports()
{
int8 count_down,count;
delay_ms(100);
buzzer_off;
setup_adc_ports(NO_ANALOGS);
output_a(0);
lcd_init();
lcd_init_custom_chars();
welcome_note();
lcd_goto(1,1);
count_down=60;
sync();
lcd_send_byte("Initializing...
");
for(count=0;count<30;count++)
{
lcd_goto(2,1);
printf(lcd_send_byte,"Wait
%02u Sec",count_down);
count_down--;
delay_ms(1000);
}
lcd_send_cmd(lcd_clear);
sync();
device_status=0;
// test_signal();
}
void
display_status()
{
//lcd_send_cmd(lcd_clear);
lcd_goto(1,1);
if(device_status==1)
lcd_send_byte("S/M
Activated ");
else
lcd_send_byte("S/M
Deactivated ");
}
void process_sms()
{
SMS_flag=0;
delay_ms(10);
strcpy(buffer_string,"ACT");
if(!strcmp(sms_buffer,buffer_string))
{
device_status=1;
strcpy(sms_buffer,"PIR:ON");
SMS_flag=1;
}
else
{
strcpy(buffer_string,"DACT");
if(!strcmp(sms_buffer,buffer_string))
{
device_status=0;
strcpy(sms_buffer,"PIR:OFF");
SMS_flag=1;
buzzer_off;
PIR_flag=0;
lcd_send_cmd(lcd_clear);
}
}
if(sms_flag)
display_status();
}
void test_buzzer()
{
buzzer_on;
delay_ms(500);
buzzer_off;
}
void main()
{
int8 check_count=0;
delay_ms(100);
test_buzzer();
init_ports();
display_status();
delay_ms(2000);
output_low(PIN_A5);
sms_no=5;
PIR_flag=0;
device_status=0;
while(TRUE)
{
if(check_count>4)
{
check_count=0;
if(check_sms())
{
process_sms();
if(SMS_flag==1)
{
delay_ms(2000);
strcpy(ph_number,phno1);
//send_sms();
delay_ms(1000);
}
}
}
if(device_status)
{
if(input(PIR_Sensor)
&& PIR_flag==0)
{
buzzer_on;
lcd_goto(2,1);
lcd_send_byte("Human
Detected ");
delay_ms(5000);
buzzer_off;
strcpy(ph_number,phno1);
strcpy(sms_buffer,"Human
Detected");
//send_sms();
PIR_flag=1;
check_count=0;
}
}
delay_ms(1000);
check_count++;
}
}
Lcd program
#define
first_line 128
#define
second_line 192
#define
third_line 148
#define
fourth_line 212
#define
lcd_clear 1
#define
cursor_on 15
#define
cursor_off 12
#define
cursor_left 16
#define
cursor_right 20
#define
LCD_CGRAM_ADDR 0x40
#define CUST_CHAR_1
0x00
#define CUST_CHAR_2
0x01
#define CUST_CHAR_3
0x02
#define CUST_CHAR_4
0x03
#define CUST_CHAR_5
0x04
#define CUST_CHAR_6
0x05
#define CUST_CHAR_7
0x06
#define CUST_CHAR_8
0x07
int8 i;
struct lcd_pin_map
{
BOOLEAN rs;
BOOLEAN rw;
BOOLEAN enable;
BOOLEAN unused;
int
data : 4;
} lcd;
#locate lcd =
getenv("sfr:PORTB") // This
puts the entire structure over the port
#define
set_tris_lcd(x) set_tris_B(x)
struct lcd_pin_map
const LCD_WRITE = {0,0,0,0,0}; // For write mode all pins are out
struct lcd_pin_map
const LCD_READ = {0,0,0,0,15}; // For read mode data pins are in
BYTE const
LCD_INIT_STRING[4] = {0x28,0x06,0x0C,0X01};
BYTE const
LCD_CUSTOM_CHARS[64] =
{0,0,0,0,31,10,4,4,
0,0,0,0,0,0,16,16,
0,0,0,0,8,8,24,24,
0,0,4,4,12,12,28,28,
2,2,6,6,14,14,30,30,
3,3,7,7,15,15,31,31,
4,4,31,4,4,10,21,27,
27,27,0,27,27,21,10,4};
BYTE
lcd_read_byte()
{
BYTE low,high;
set_tris_lcd(LCD_READ);
lcd.rs = 0;
delay_cycles(1);
lcd.rw = 1;
delay_cycles(1);
lcd.enable = 1;
delay_cycles(1);
high = lcd.data;
lcd.enable = 0;
delay_cycles(1);
lcd.enable = 1;
delay_us(1);
low = lcd.data;
lcd.enable = 0;
set_tris_lcd(LCD_WRITE);
return( (high<<4) | low);
}
BYTE read_lcd()
{
BYTE low,high;
while ( bit_test(lcd_read_byte(),7) ) ;
set_tris_lcd(LCD_READ);
lcd.rs = 1;
delay_cycles(1);
lcd.rw = 1;
delay_cycles(1);
lcd.enable = 1;
delay_cycles(1);
high = lcd.data;
lcd.enable = 0;
delay_cycles(1);
lcd.enable = 1;
delay_us(1);
low = lcd.data;
lcd.enable = 0;
set_tris_lcd(LCD_WRITE);
return( (high<<4) | low);
}
void
lcd_send_nibble( BYTE nibb ) {
lcd.data = nibb;
delay_cycles(1);
lcd.enable = 1;
delay_us(2);
lcd.enable = 0;
}
void
lcd_send_byte(BYTE n )
{
while ( bit_test(lcd_read_byte(),7) ) ;
delay_ms(1);
lcd.rs = 1;
delay_cycles(1);
lcd.rw = 0;
delay_cycles(1);
lcd.enable = 0;
lcd_send_nibble(n >> 4);
lcd_send_nibble(n & 0xf);
}
void
lcd_send_cmd(BYTE n )
{
while ( bit_test(lcd_read_byte(),7) ) ;
delay_ms(1);
lcd.rs = 0;
delay_cycles(1);
lcd.rw = 0;
delay_cycles(1);
lcd.enable = 0;
lcd_send_nibble(n >> 4);
lcd_send_nibble(n & 0xf);
}
void lcd_out(int8
*_dest_reg)
{
while(*_dest_reg)
{
lcd_send_byte(*_dest_reg);
_dest_reg++;
}
}
int1
is_lcd_connected()
{
byte temp=0;
lcd_send_cmd(0x80);
lcd_send_byte('B');
lcd_send_cmd(0x80);
temp=read_lcd();
if(temp!='B')
return 0;
else
return 1;
}
void lcd_init() {
BYTE i;
set_tris_lcd(LCD_WRITE);
lcd.rs = 0;
lcd.rw = 0;
lcd.enable = 0;
delay_ms(15);
for(i=0;i<3;i++) {
lcd_send_nibble(3);
delay_ms(5);
}
lcd_send_nibble(2);
for(i=0;i<4;i++)
lcd_send_cmd(LCD_INIT_STRING[i]);
while(!is_lcd_connected());
lcd_send_cmd(lcd_clear);
}
void lcd_goto(int8
x, int8 y)
{
int8 address;
switch(x)
{
case 1:
address = first_line;
break;
case 2:
address = second_line;
break;
case 3:
address = third_line;
break;
case 4:
address = fourth_line;
break;
default:
address = first_line;
break;
}
address += (Y-1);
lcd_send_cmd(address);
}
void
lcd_init_custom_chars()
{
BYTE i;
lcd_send_cmd(LCD_CGRAM_ADDR);
for(i=0;i<=63;i++)
{
lcd_send_byte(LCD_CUSTOM_CHARS[i]);
delay_ms(2);
}
}
void welcome_note()
{
lcd_send_cmd(lcd_clear);
lcd_goto(1,1);
lcd_send_byte("Human Detection ");
lcd_goto(2,1);
lcd_send_byte(" And Remote
");
delay_ms(1000);
lcd_goto(1,1);
lcd_send_byte(" Notification
");
lcd_goto(2,1);
lcd_send_byte(" Using GSM
");
delay_ms(1000);
lcd_send_cmd(lcd_clear);
}
SIM CARD
PROGRAM
#users232(baud=9600,xmit=pin_C6,rcv=pin_C7,parity=n,bits=8,stop=1,stream=GSM,timeout=500)
int8 sms_buffer[40],ph_number[15];
void sync()
{
fprintf(GSM,"AT\n\r");
delay_ms(100);
fprintf(GSM,"AT\n\r");
delay_ms(100);
fprintf(GSM,"AT\n\r");
delay_ms(100);
fprintf(GSM,"AT\n\r");
delay_ms(100);
}
void dial_modem()
{
int8 i=0;
fputc('A',GSM);
fputc('T',GSM);
fputc('D',GSM);
fputc(' ',GSM);
while(ph_number[i] !='\0' &&
i<16)
{
fputc(ph_number[i],GSM);
i++;
}
fputc(';',GSM);
fputc(0x0D,GSM);
fputc(0x0A,GSM);
}
void hang_call()
{
fputc('A',GSM);
fputc('T',GSM);
fputc('H',GSM);
fputc(0x0D,GSM);
fputc(0x0A,GSM);
}
void
set_text_mode()
{
sync();
fprintf(GSM,"AT+CMGF=1\n\r");
}
int1 read_char(int8
check_char)
{
int8 rx_no,rx_char;
for(rx_no=0;rx_no<50;rx_no++)
{
rx_char=fgetc(GSM);
if(rx_char==check_char)
return 1;
}
return 0;
}
int1 get_sms(int8
intex_no)
{
int8 count=0,success_flag=0;
set_text_mode();
delay_ms(100);
fprintf(GSM,"AT+CMGR=%u\n\r",intex_no);
//while(fgetc(GSM)!=0x0A);
if(read_char(0x0A))
{
if(fgetc(GSM)=='+')
{
//while(fgetc(GSM)!='"');
if(read_char('"'))
{
//while(fgetc(GSM)!='"');
if(read_char('"'))
{
//while(fgetc(GSM)!='"');
if(read_char('"'))
{
do
{
ph_number[count]=fgetc(GSM);
count++;
}while(ph_number[count-1]
!='"' && count<15);
ph_number[count-1]='\0';
//while(fgetc(GSM)!=0x0A);
if(read_char(0x0A))
{
count=0;
do
{
sms_buffer[count]=fgetc(GSM);
count++;
}while(sms_buffer[count-1]
!=0x0D && count<24);
sms_buffer[count-1]='\0';
if(count<24)
{
delay_ms(500);
sync();
fprintf(GSM,"AT+CMGD=%u\n\r",intex_no);//delete
sms
success_flag=1;
}
}
}
}
}
}
}
if(success_flag)
{
return 1;
}
else
{
return 0;
}
}
void send_sms()
{
int8 array_index;
set_text_mode();
delay_ms(100);
fprintf(GSM,"AT+CMGS=");
fputc('"',GSM);
array_index=0;
while(ph_number[array_index] !='\0')
{
fputc(ph_number[array_index],GSM);
array_index++;
}
fputc('"',GSM);
fputc(0x0D,GSM);
// fputc(0x0A,GSM);
while(fgetc(GSM) !=' ');
array_index=0;
while(sms_buffer[array_index] !='\0')
{
fputc(sms_buffer[array_index],GSM);
array_index++;
}
fputc(0x1A,GSM);// Ctrl-Z
delay_ms(100);
fgetc(GSM);
}
//int8
read_strength()
//{
// int8 rssi[3],rssi_byte;
// //output_low(PIN_A5);
// fprintf(GSM,"AT+CSQ\n\r");
// while(fgetc(GSM) !=' ');
// //output_high(PIN_A5);
// rssi[0]=fgetc(GSM) & 0x0F;
// rssi[1]=fgetc(GSM) & 0x0F;
// rssi_byte=rssi[0]*10;
// rssi_byte=rssi_byte+rssi[1];
// return rssi_byte;
//}
int8
read_strength()
{
int8 rssi[3],rssi_byte=5;
//output_low(PIN_A5);
fprintf(GSM,"AT+CSQ\n\r");
if(read_char(' '))
{
//output_high(PIN_A5);
rssi[0]=fgetc(GSM) & 0x0F;
rssi[1]=fgetc(GSM) & 0x0F;
rssi_byte=rssi[0]*10;
rssi_byte=rssi_byte+rssi[1];
}
return rssi_byte;
}
MPLAB COMPILER
MPLAB COMPILER
In this
project software section compiling is done using an MPLAB compiler.
MPLAB ICD 2
The MPLAB
ICD 2 is a low-cost in-circuit serial programmer (ICSP). MPLAB ICD 2 is
intended to be used as a programming aid in a laboratory environment. The MPLAB
ICD 2 offers these features:
• Target
Vdd monitor
•
Diagnostic LEDs
• MPLAB
IDE user interface
• RS-232
serial interface to a host PC
Installing and Configuring MPLAB IDE for MPLAB ICD 2
To
install the MPLAB IDE software, first acquire the latest MPLAB IDE installation
executable (MPxxxxx.exe, where xxxxx represents the version of MPLAB IDE) from
the Microchip web site (www.microchip.com)
Serial Communications
Connect
the RS-232 cable to the MPLAB ICD 2 and the PC. The Flow Control and FIFO
settings must be set properly for a serial communications port on a PC with a
Windows operating system.
Changing Serial
Port
Complete
the following steps to change the Flow Control and FIFO settings for a serial communications
port on a PC running the Windows operating system.
Windows 2000/XP
1.
On your PC, select Start>Settings>Control Panel.
2.
In the Control Panel, double click the System Icon.
3.
In the Systems Properties dialog, click the Hardware
tab and click the Device Manager Button.
4.
Double click "Ports (COM & LPT)" to expand
the Ports selection.
5.
Double click the I/O port to which the MPLAB ICD 2 is
connected.
6.
Select the Port Settings tab.
7.
In the Flow Control field, select Hardware.
8.
Click the Advanced button, deselect the
"Use FIFO" box, and click OK.
9. Reboot the PC to implement the change.
Setup Wizard
1.
Select Programmer
Programmer
> Select Programmer > MPLAB ICD 2
 |
2. Setup wizard
A setup
wizard is available from Programmer>MPLAB ICD 2 Setup Wizard to
help walk you through setting up your MPLAB ICD 2.
3. Setup Wizard –
Welcome
The
MPLAB ICD2 Setup Wizard will open. Follow the dialogs in the MPLAB ICD 2 Wizard
to set up MPLAB ICD 2 for use with MPLAB IDE.
Click Next to continue.
4.
Setup Wizard - Select a Port
 |
Click Next to continue
5. Setup Wizard -
Select Target Power
Select
target power source - Choose Target has own power supply
Click Next to continue.
- Setup Wizard - Enable Auto Connect
Enable auto connection -
Set up MPLAB IDE to automatically connect to MPLAB ICD 2 on project start-up.
Click Next to continue.
- Setup Wizard - Enable Automatic OS Download
Enable auto download of
operating systems - Automatically download the correct OS for the selected
device.
Click Next to continue.
- Setup Wizard - Summary
Check the summarized
information. If anything is incorrect, use Back to return to the dialog
you need and change the information.
 |
Click Finish when you are
satisfied with the MPLAB ICD 2 setup.
PCB LAYOUT
PCB FABRICATION
PCB FABRICATION
A printed circuit board,
or PCB, is used to mechanically
support and electrically connect electronic components using conductive pathways, tracks or signal traces etched from copper sheets laminated
onto a non-conductive substrate. It is also referred to as printed wiring board (PWB) or etched wiring board. A PCB populated with electronic components is
a printed circuit assembly (PCA), also known as a printed circuit board assembly (PCBA)
PCBs are inexpensive, and can be highly reliable. They require much more
layout effort and higher initial cost than either wire wrap
or point-to-point construction, but are
much cheaper and faster for high-volume production; the production and
soldering of PCBs can be done by totally automated equipment. Much of the
electronics industry's PCB design, assembly, and quality control needs are set
by standards that are published by the IPC organization.
MANUFACTURING
Materials
Conducting layers are typically made of thin copper foil.
Insulating layers dielectric is typically laminated together with epoxy resin
prepreg. The
board is typically coated with a solder mask that is green in color. Other
colors that are normally available are blue, black, white and red. There are
quite a few different dielectrics that can be chosen to provide different
insulating values depending on the requirements of the circuit. Some of these
dielectrics are polytetrafluoroethylene (Teflon), FR-4, FR-1,
CEM-1 or CEM-3. Well known prepreg materials used in the PCB industry are FR-2 (Phenolic cotton
paper), FR-3 (Cotton paper and epoxy), FR-4 (Woven glass and
epoxy), FR-5 (Woven glass and epoxy), FR-6 (Matte glass and polyester), G-10
(Woven glass and epoxy), CEM-1 (Cotton paper and epoxy), CEM-2 (Cotton paper
and epoxy), CEM-3 (Woven glass and epoxy), CEM-4 (Woven glass and epoxy), CEM-5
(Woven glass and polyester).
Patterning
(etching)
The vast majority
of printed circuit boards are made by bonding a layer of copper over the entire
substrate, sometimes on both sides, (creating a "blank PCB") then
removing unwanted copper after applying a temporary mask (e.g. by etching),
leaving only the desired copper traces. A few PCBs are made by adding traces to the bare substrate
(or a substrate with a very thin layer of copper) usually by a complex process
of multiple electroplating steps. The PCB manufacturing method
primarily depends on whether it is for production volume or sample/prototype
quantities.
There are three common "subtractive" methods (methods that remove
copper) used for the production of printed circuit boards:- Silk screen printing uses etch-resistant inks to protect the copper foil. Subsequent etching removes the unwanted copper. Alternatively, the ink may be conductive, printed on a blank (non-conductive) board. The latter technique is also used in the manufacture of hybrid circuits.
- Photoengraving
uses a photo mask and developer to selectively remove a photo
resist coating. The remaining photo resist protects the copper foil.
Subsequent etching removes the unwanted copper. The photo mask is usually
prepared with a photo plotter from data produced by a technician
using
- PCB milling uses a two or three-axis mechanical milling system to mill away the copper foil from the substrate. A PCB milling machine (referred to as a 'PCB Proto typer') operates in a similar way to a plotter, receiving commands from the host software that control the position of the milling head in the x, y, and (if relevant) z axis. Data to drive the Proto type is extracted from files generated in PCB design software and stored in HPGL or Gerber file format.
"Additive" processes also
exist. The most common is the "semi-additive" process. In this
version, the unpatented board has a thin layer of copper already on it. A
reverse mask is then applied. (Unlike a subtractive process mask, this mask
exposes those parts of the substrate that will eventually become the traces.)
Additional copper is then plated onto the board in the unmasked areas; copper
may be plated to any desired weight. Tin-lead or other surface plantings are
then applied. The mask is stripped away and a brief etching step removes the
now-exposed original copper laminate from the board, isolating the individual
traces. Some boards with plated through holes but still single sided were made
with a process like this. General
Electric made consumer radio sets in the late 1960s using boards like
these. The additive process is commonly used for multi-layer boards as it
facilitates the plating-through
of the holes (to produce conductive vias) in the circuit board.
Lamination
Some PCBs have
trace layers inside the PCB and are called multi-layer PCBs. These are formed by bonding together
separately etched thin boards.
Drilling
Holes through a PCB
are typically drilled with small-diameter drill bits
made of solid coated tungsten carbide. Coated tungsten carbide is
recommended since many board materials are very abrasive and drilling must be
high RPM and high feed to be cost effective. Drill bits must also remain sharp
to not mar or tear the traces. Drilling with high-speed-steel is simply not
feasible since the drill bits will dull quickly and thus tear the copper and
ruin the boards. The drilling is performed by automated drilling
machines with placement controlled by a drill tape or drill
file. These computer-generated files are also called numerically controlled drill (NCD)
files or "Excellon files". The drill file describes the
location and size of each drilled hole. These holes are often filled with
annular rings (hollow rivets) to create vias. Vias allow the electrical and thermal
connection of conductors on opposite sides of the PCB. When very small vias are
required, drilling with mechanical bits is costly because of high rates of wear
and breakage. In this case, the vias may be evaporated by lasers. Laser-drilled
vias typically have an inferior surface finish inside the hole. These holes are
called micro vias.
It is also possible
with controlled-depth drilling,
laser drilling, or by pre-drilling the individual sheets of the PCB before
lamination, to produce holes that connect only some of the copper layers,
rather than passing through the entire board. These holes are called blind vias when they connect an
internal copper layer to an outer layer, or buried vias when they connect two or more internal copper layers
and no outer layers.
The walls of the
holes, for boards with 2 or more layers, are made conductive then plated with
copper to form plated-through holes
that electrically connect the conducting layers of the PCB. For multilayer
boards, those with 4 layers or more, drilling typically produces a smear of the high temperature
decomposition products of bonding agent in the laminate system. Before the
holes can be plated through, this smear
must be removed by a chemical de-smear
process, or by plasma-etch.
Removing (etching back) the smear also reveals the interior conductors as well.
Exposed
conductor plating and coating
PCBs are plated
with solder, tin, or gold over nickel as a resist for etching away the
unneeded underlying copper After PCBs are etched and then rinsed with water,
the solder mask is applied, and then any exposed copper is coated with solder,
nickel/gold, or some other anti-corrosion coating.
Matte solder is
usually fused to provide a better bonding surface or stripped to bare copper.
Treatments, such as benzimidazolethiol, prevent surface oxidation of bare
copper. The places to which components will be mounted are typically plated,
because untreated bare copper oxidizes quickly, and therefore is not readily
solder able. Traditionally, any exposed copper was coated with solder by hot
air solder leveling (HASL).
The HASL finish prevents oxidation from the underlying copper, thereby
guaranteeing a solder able surface.[9]
This solder was a tin-lead alloy, however new
solder compounds are now used to achieve compliance with the RoHS directive in the EU and US, which restricts
the use of lead. One of these lead-free compounds is SN100CL, made up of 99.3%
tin, 0.7% copper, 0.05% nickel, and a nominal of 60ppm germanium. It is
important to use solder compatible with both the PCB and the parts used. An
example is Ball Grid Array (BGA) using tin-lead solder balls for connections
losing their balls on bare copper traces or using lead-free solder paste .Other
plating’s used are OSP (organic surface protectant), immersion silver (IAg), immersion tin,
electro less nickel with immersion gold coating (ENIG), and direct gold
plating (over nickel). Edge connectors, placed along one edge of some
boards, are often nickel plated then gold plated.
Another coating consideration is rapid diffusion of coating metal into Tin
solder. Tin forms inter metallic’s such as Cu5Sn6 and Ag3Cu
that dissolve into the Tin liquids or solidus (@50C), stripping surface coating
and/or leaving voids.
Electrochemical migration (ECM) is
the growth of conductive metal filaments on or in a printed circuit board (PCB)
under the influence of a DC voltage bias.[10][11]
Silver, zinc, and aluminum are known to grow whiskers under the influence of an
electric field. Silver also grows conducting surface paths in the presence of
halide and other ions, making it a poor choice for electronics use. Tin will
grow "whiskers" due to tension in the plated surface. Tin-Lead or
Solder plating also grows whiskers, only reduced by the percentage Tin
replaced. Reflow to melt solder or tin plate to relieve surface stress lowers
whisker incidence. Another coating issue is tin pest, the
transformation of tin to a powdery allotrope at low temperature.[12]\
Solder
resist
Areas that should
not be soldered may be covered with a polymer solder resist (solder
mask) coating. The solder resist prevents solder from bridging between
conductors and creating short circuits. Solder resist also provides some
protection from the environment. Solder resist is typically 20–30 micro meters
thick.
Screen
printing
Line art and text
may be printed onto the outer surfaces of a PCB by screen
printing. When space permits, the screen print text can indicate component designators, switch setting requirements,
test points, and other features helpful in assembling, testing, and servicing
the circuit board. Screen print is also known as the silk screen, or, in one sided PCBs, the red print .Lately some digital printing solutions have been
developed to substitute the traditional screen printing process. This
technology allows printing variable data onto the PCB, including serialization
and barcode information for traceability purposes.
Test
Unpopulated boards
may be subjected to a bare-board test
where each circuit connection (as defined in a netlist) is verified as correct on the finished board. For
high-volume production, a Bed of nails tester, a fixture or a Rigid needle adapter is used to make contact
with copper lands or holes on one or both sides of the board to facilitate
testing. A computer will instruct
the electrical test unit to apply a small voltage to each contact point on the
bed-of-nails as required, and verify that such voltage appears at other
appropriate contact points. A "short" on a board would be a
connection where there should not be one; an "open" is between two
points that should be connected but are not. For small- or medium-volume
boards, flying
probe and flying-grid
testers use moving test heads to make contact with the
copper/silver/gold/solder lands or holes to verify the electrical connectivity
of the board under test. Another method for testing is industrial CT scanning, which can generate a
3D rendering of the board along with 2D image slices and can show details such
a soldered paths and connections.
Printed
circuit assembly
After the printed
circuit board (PCB) is completed, electronic components must be attached to
form a functional printed circuit
assembly,[13][14]
or PCA (sometimes called a "printed circuit board assembly" PCBA). In
through-hole
construction, component leads are inserted in holes. In surface-mount construction, the components are
placed on pads or lands on the outer surfaces of the
PCB. In both kinds of construction, component leads are electrically and
mechanically fixed to the board with a molten metal solder.There are a variety
of soldering
techniques used to attach components to a PCB. High volume production is
usually done with machine placement and bulk wave soldering
or reflow ovens, but skilled technicians are able to solder very tiny parts
(for instance 0201 packages which are 0.02 in. by 0.01 in.)[15]
by hand under a microscope, using tweezers and a fine tip soldering
iron for small volume prototypes. Some parts are impossible to solder by
hand, such as ball grid array (BGA) packages.Often, through-hole
and surface-mount construction must be combined in a single assembly because
some required components are available only in surface-mount packages, while
others are available only in through-hole packages. Another reason to use both
methods is that through-hole mounting can provide needed strength for
components likely to endure physical stress, while components that are expected
to go untouched will take up less space using surface-mount techniques.
After the board has been populated
it may be tested in a variety of ways:
Ø While
the power is off, visual inspection, automated optical inspection. JEDEC guidelines for
PCB component placement, soldering, and inspection are commonly used to
maintain quality control in this stage of PCB manufacturing.
Ø While
the power is off, analog signature analysis, power-off
testing.
Ø While
the power is on, in-circuit test, where physical measurements (i.e.
voltage, frequency) can be done.
Ø While
the power is on, functional test, just checking if the PCB does what
it had been designed for.
To facilitate these
tests, PCBs may be designed with extra pads to make temporary connections.
Sometimes these pads must be isolated with resistors. The in-circuit test may
also exercise boundary scan test features of some components.
In-circuit test systems may also be used to program nonvolatile memory
components on the board. In boundary scan testing, test circuits integrated
into various ICs on the board form temporary connections between the PCB traces
to test that the ICs are mounted correctly. Boundary scan testing requires that
all the ICs to be tested use a standard test configuration procedure, the most
common one being the Joint Test Action Group (JTAG) standard. The JTAG test architecture
provides a means to test interconnects between integrated circuits on a board
without using physical test probes. JTAG tool vendors provide various types of stimulus and
sophisticated algorithms, not only to detect the failing nets, but also to
isolate the faults to specific nets, devices, and pins.[16]
Protection
and packaging
PCBs intended for
extreme environments often have a conformal
coating, which is applied by dipping or spraying after the components have
been soldered. The coat prevents corrosion and leakage currents or shorting due
to condensation. The earliest conformal coats were wax; modern conformal
coats are usually dips of dilute solutions of silicone rubber, polyurethane,
acrylic, or epoxy. Another technique for applying a conformal coating is for
plastic to be sputtered onto the PCB in a vacuum chamber. The
chief disadvantage of conformal coatings is that servicing of the board is
rendered extremely difficult. Many assembled PCBs are static sensitive, and therefore must be
placed in antistatic bags during transport. When handling
these boards, the user must be grounded (earthed). Improper handling
techniques might transmit an accumulated static charge through the board,
damaging or destroying components. Even bare boards are sometimes static
sensitive. Traces have become so fine that it's quite possible to blow an etch
off the board (or change its characteristics) with a static charge. This is
especially true on non-traditional PCBs such as MCMs
and microwave PCBs.
Design
Ø Schematic
capture or schematic entry is done through an EDA tool.
Ø Card
dimensions and template are decided based on required circuitry and case of the
PCB. Determine the fixed components and heat sinks
if required.
Ø Deciding
stack layers of the PCB. 4 to 12 layers or more depending on design complexity.
Ground
plane and Power plane are decided. Signal planes where signals
are routed are in top layer as well as internal layers.[18]
Ø Line
impedance determination using dielectric layer thickness, routing copper
thickness and trace-width. Trace separation also taken into account in case of
differential signals. Microstrip, stripline or
dual stripline can be used to route signals.
Ø Placement
of the components. Thermal considerations and geometry are taken into account. Vias and lands are marked.
Ø Routing
the signal
trace. For optimal EMI
performance high frequency signals are routed in internal layers between power
or ground planes as power plane behaves as ground for AC.
Ø Gerber file
generation for manufacturing.
Safety
certification (US)
Safety Standard UL
796 covers component safety requirements for printed wiring boards for use as
components in devices or appliances. Testing analyzes characteristics such as
flammability, maximum operating temperature, electrical tracking,
heat deflection, and direct support of live electrical parts
Multiwire boards
Multiwire is a
patented technique of interconnection which uses machine-routed insulated wires
embedded in a non-conducting matrix (often plastic resin). It was used during
the 1980s and 1990s. (Kollmorgen Technologies Corp., U.S. Patent 4,175,816)
Multiwire is still available in 2010 through Hitachi
Since it was quite
easy to stack interconnections (wires) inside the embedding matrix, the
approach allowed designers to forget completely about the routing of wires
(usually a time-consuming operation of PCB design): Anywhere the designer needs
a connection; the machine will draw a wire in straight line from one
location/pin to another. This led to very short design times (no complex
algorithms to use even for high density designs) as well as reduced crosstalk
(which is worse when wires run parallel to each other—which almost never happen
in Multiwire), though the cost is too high to compete with cheaper PCB
technologies when large quantities are needed.
Surface-mount
technology
Surface mount components, including resistors, transistors
and an integrated circuit Surface-mount technology emerged in the 1960s, gained
momentum in the early 1980s and became widely used by the mid 1990s. Components
were mechanically redesigned to have small metal tabs or end caps that could be
soldered directly on to the PCB surface. Components became much smaller and
component placement on both sides of the board became more common than with
through-hole mounting, allowing much higher circuit densities. Surface mounting
lends itself well to a high degree of automation, reducing labor costs and greatly
increasing production and quality rates. Carrier Tapes provide a stable and
protective environment for Surface mount devices (SMDs) which can be
one-quarter to one-tenth of the size and weight, and passive components can be
one-half to one-quarter of the cost of corresponding through-hole parts.
However, integrated circuits are often priced the same regardless of the
package type, because the chip itself is the most expensive part. As of 2006,
some wire-ended components, such as small-signal switch diodes, e.g. 1N4148, are
actually significantly cheaper than corresponding SMD versions.
SOLDERING
Soldering
Soldering is
a process in which two or more metal items are joined together by melting and flowing a filler
metal into the joint, the filler metal having a lower melting
point than the work piece. Soldering differs from welding in that
the work pieces are not melted. There are three forms of soldering, each
requiring higher temperatures and each producing an increasingly stronger joint
strength: soft soldering which
originally used a tin-lead alloy as the filler metal, silver
soldering which uses an alloy containing silver and brazing which
uses a brass alloy
for the filler. The alloy of the filler metal for each type of soldering can be
adjusted to modify the melting temperature of the filler. Soldering appears to
be a hot glue process, but it differs from gluing significantly in that
the filler metals alloy with the work piece at the junction to form a gas and
liquid tight bond.[1]
Applications
Soldering was
historically used to make jewelry items, cooking ware and tools. Currently, the
two most common uses of soldering are in plumbing and in electronics where it
is used to connect electrical wiring and to connect electronic components to printed circuit boards (PCBs). It provides
reasonably permanent but reversible connections between copper pipes in plumbing
systems as well as joints in sheet metal objects such as food cans, roof flashing, rain
gutters and automobile radiators. Jewelry components, machine tools and some refrigeration and
plumbing components are often assembled and repaired by the higher temperature
silver soldering process. Small mechanical parts are often soldered or brazed
as well. Soldering is also used to join lead came and copper foil in stained glass work. It can also
be used as a semi-permanent patch for a leak in a container or cooking vessel.
Solders
Soldering filler
materials are available in many different alloys for differing
applications. In electronics assembly, the eutectic alloy
of 63% tin and 37% lead (or 60/40, which is almost identical in performance to
the eutectic) has been the alloy of choice. Other alloys are used for plumbing,
mechanical assembly, and other applications.
A eutectic formulation has several
advantages for soldering; chief among these is the coincidence of the liquidus and solidus temperatures, i.e. the absence of a
plastic phase. This allows for quicker wetting as the solder heats up, and
quicker setup as the solder cools. A non-eutectic formulation must remain still
as the temperature drops through the liquidus and solidus temperatures. Any
differential movement during the plastic phase may result in cracks, giving an
unreliable joint. Additionally, a eutectic formulation has the lowest possible
melting point, which minimizes heat stress on electronic components during
soldering.
Flux
The purpose of flux is to facilitate the soldering process. The
obstacle to a successful solder joint is an impurity at the site of the union,
e.g. dirt, oils or oxidation. The impurities can be removed by mechanical
cleaning or by chemical means, but the elevated temperatures required to melt
the filler metal (the solder) encourages the work piece (and the solder) to
re-oxidize. This effect is accelerated as the soldering temperatures increase
and can completely prevent the solder from joining to the work piece. One of
the earliest forms of flux was charcoal, which acts as a reducing
agent and helps prevent oxidation during the soldering process. Some fluxes
go beyond the simple prevention of oxidation and also provide some form of
chemical cleaning (corrosion).
For many years, the
most common type of flux used in electronics (soft soldering) was rosin-based, using
the rosin from selected pine trees. It was ideal in that it was non-corrosive
and non-conductive at normal temperatures but became mildly reactive
(corrosive) at the elevated soldering temperatures. Plumbing and automotive
applications, among others, typically use an acid-based (muriatic
acid) flux which provides cleaning of the joint. These fluxes cannot be
used in electronics because they are conductive and because they will
eventually dissolve the small diameter wires. Many fluxes also act as a wetting
agent in the soldering process,[5]
reducing the surface tension of the molten solder and causing it
to flow and wet the work pieces more easily.
Soldering iron
A soldering iron
is a hand
tool most commonly used in soldering. It supplies heat to melt the solder so that it
can flow into the joint between two work pieces.A soldering iron is composed of
a heated metal tip and an insulated handle. Heating is often achieved
electrically, by passing an electric current (supplied through an electrical
cord or battery cables) through the resistive material of a heating
element. Another heating method includes combustion of a suitable gas,
which can either be delivered through a tank mounted on the iron (flameless),
or through an external flame.
The various steps
that are involved in a soldering procedure are given below:
1.Make
the layout of the connection of the component in the circuit .plug in the chord
of the soldering iron to the main supply to get it heated.
2.Strengthen
and clean the component leads using blades or knifes. Apply little flux on the
leads. Take a little solder on the soldering iron and apply the molten solder
on the leads. Care must be taken to avoid the component getting heated up.
3.Mount
the component on the PCB, by bending the leads of the component using the noise
pliers.
4.Apply
flux on the joints and solder the joints. Soldering must be done in maximum to
avoid the dry soldering and heating up the components.
5.wash
the residue using and brush
CONCLUSION
GSM technology capable solution has
proved to be controlled remotely, provide home security and is cost-effective
as compared to the previously existing systems. When live in a dynamic world of
fast changing technical frontiers, the conventional systems are being replaced
by sophisticated and advanced technologies. Keeping the latest and trends. The
designed product is an innovative one to facilitate the automation
requirements. The drawbacks of the existing manual system, which involves
wastage of electricity due to in efficient operation of fans and lights, can be
solved.
Security systems
today needs to make use of the latest available technological components. In
this paper, we present the design and implementation of a remote sensing,
control, and home security system based on GSM (Global System for Mobile
BIBILIOGRAPHY
There were many sources from where the ideas and
materials for preparing this training report were used. The following are worth
listing:-
Site
referred
Books
referred
Ø ELECTRONICS
FOR YOU
Ø EMBEDDED
SYSTEMS
Ø PCB
DESIGN WITH ORCAD: STEVE SINCHAK&DAN HOOPER
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