25.wireless data communication
TRANSCRIPT
INDEX
1. INTRODUCTION
2. MICROCONTROLLER
2.1 A Brief History of 8051
2.2 Description of 89C52 Microcontroller
2.3 Block Diagram of Microcontroller
2.4 Pin Configurations
2.5 Timers
2.6 Interrupts
2.7 Special function registers:
2.8 Memory Organization
3. POWER SUPPLY
3.1 Description
3.2 Block Diagram
3.3 Circuit Diagram
3.4 IC Voltage Regulators
4. ULN 2003
4.1 Pin Connection
4.2 Description
5. LCD
5.2 Description
5.1 Pin Connection
6.1 Description RF Receiver Module - RX433
6.2 RF Transmitter Module-TX433
7. KEIL SOFTWARE
8.1 Software Description
9. CIRCUIT DIAGRAM
10.SOURCE CODING
11.CONCLUSION
FUTURE SCOPE
BIBLIOGRAPHY
REFERENCES
Wireless Data Transfer using RF Communication
ABSTRACT
In Today’s Electronic communication take important role. Using
Today’s Communication technology the data transmission and reception from one
Place to another is easy and fast.
In our project we have two sections, one is transmitter another one
Receiver, in transmitting section we have AT89C52 Microcontroller, PC and
LCD. In receiver section we have another AT89C52Microcontroller and LCD
At the time when data will transfer from the transmitter a predefined code will be
Added with every eight bit data and when this data receive by the receiver this code
Will be decode by the receiver and generate the exact data that will be displayed
On LCD.
In this project Wireless Encoding and decoding are using one of the techniques
Called cipher text technique. Encryption is any procedure to convert plaintext into
Cipher text. Decryption is any procedure to convert cipher text into plaintext.
Hardware components:
AT 89C52 Micro controllers LCD RF Module. MAX 232 DB-9 Connector.
Software tools:
Kiel vision.
Advantages:
The data secure is more while transferring data Used in data communication.
Applications:
This system can be used for Military application for security.
It can be used in Air craft applications.
BLOCK DIAGRAM
TRANSMITTER RECEIVER
EMBEDDED CONTROLLER
LCD
RegulatedPower Supply
RF Receiver module
EMBEDDED CONTROLLER
MAX232
RegulatedPower supply
RF Transmitter
module
PC
2. MICROCONTROLLER
2.1 A Brief History of 8051
In 1981, Intel Corporation introduced an 8 bit microcontroller
called 8051. This microcontroller had 128 bytes of RAM, 4K bytes of chip
ROM, two timers, one serial port, and four ports all on a single chip. At
the time it was also referred as “A SYSTEM ON A CHIP”
The 8051 is an 8-bit processor meaning that the CPU can work
only on 8 bits data at a time. Data larger than 8 bits has to be broken
into 8 bits pieces to be processed by the CPU. The 8051 has a total of
four I\O ports each 8 bit wide.
There are many versions of 8051 with different speeds and
amount of on-chip ROM and they are all compatible with the original
8051. This means that if you write a program for one it will run on any of
them.
The 8051 is an original member of the 8051 family. There are two
other members in the 8051 family of microcontrollers. They are 8052
and 8031. All the three microcontrollers will have the same internal
architecture, but they differ in the following aspects.
8031 has 128 bytes of RAM, two timers and 6
interrupts.
89C51 has 4KB ROM, 128 bytes of RAM, two
timers and 6 interrupts.
89C52 has 8KB ROM, 128 bytes of RAM, three
timers and 8 interrupts.
Of the three microcontrollers, 89C51 is the most preferable.
Microcontroller supports both serial and parallel communication.
In the concerned project 89C52 microcontroller is used. Here
microcontroller used is AT89C52, which is manufactured by ATMEL
laboratories.
2.2 Description of 89C52 Microcontroller
The AT89C52 provides the following standard features: 8Kbytes of
Flash, 256 bytes of RAM, 32 I/O lines, three 16-bit timer/counters, six-
vector two-level interrupt architecture, a full duplex serial port, on-chip
oscillator, and clock circuitry. In addition, the AT89C52 is designed with
static logic for operation down to zero frequency and supports two
software selectable power saving modes. The Idle Mode stops the CPU
while allowing the RAM, timer/counters, serial port, and interrupt system
to continue functioning. The Power down Mode saves the RAM contents
but freezes the oscillator, disabling all other chip functions until the next
hardware reset.
By combining a versatile 8-bit CPU with Flash on a monolithic chip,
the AT89C52 is a powerful microcomputer which provides a highly
flexible and cost effective solution to many embedded control
applications.
Features of Microcontroller (89C52)
Compatible with MCS-51 Products
8 Kbytes of In-System Reprogrammable Flash Memory
Endurance: 1,000 Write/Erase Cycles
Fully Static Operation: 0 Hz to 24 MHz
Three-Level Program Memory Lock
256 x 8-Bit Internal RAM
32 Programmable I/O Lines
Three 16-Bit Timer/Counters
Eight vector two level Interrupt Sources
Programmable Serial Channel
Low Power Idle and Power Down Modes
In addition, the AT89C52 is designed with static logic for operation
down to zero frequency and supports two software selectable power
saving modes.
The Idle Mode stops the CPU while allowing the RAM,
timer/counters, serial port and interrupt system to continue functioning.
The Power down Mode saves the RAM contents but freezes the oscillator
disabling all other chip functions until the next hardware reset.
2.3 Block Diagram of Microcontroller
Figure 2.1 Block Diagram Of 89C52
2.4 Pin Configurations
Figure 2.2 Pin Diagram of 89C52
Pin Description
VCC
Pin 40 provides Supply voltage to the chip. The voltage source is +5v
GND.
Pin 20 is the grounded
Port 0
Port 0 is an 8-bit open drain bidirectional I/O port from pin 32 to
39. As an output port each pin can sink eight TTL inputs. When 1s are
written to port 0 pins, the pins can be used as high-impedance inputs.
Port 0 may also be configured to be the multiplexed low-order
address/data bus during accesses to external program and data
memory. In this mode P0 has internal pull-ups.
Port 0 also receives the code bytes during Flash programming,
and outputs the code bytes during program verification. External pull-
ups are required during program verification.
Port 1
Port 1 is an 8-bit bidirectional I/O port with internal pull-ups from
pin 1 to 8. The Port 1 output buffers can sink/source four TTL inputs.
When 1s are written to Port 1 pins they are pulled high by the internal
pull-ups and can be used as inputs. As inputs, Port 1 pins that are
externally being pulled low will source current (IIL) because of the
internal pull-ups.
In addition, P1.0 and P1.1 can be configured to be the
timer/counter 2 external count input (P1.0/T2) and the timer/counter 2
trigger input (P1.1/T2EX), respectively, as shown in following table.
Port 1 also receives the low-order address bytes during Flash
programming and program verification.
Port 2
Port 2 is an 8-bit bidirectional I/O port with internal pull-ups from
pin 21 to 28. The Port 2 output buffers can sink / source four TTL inputs.
When 1s are written to Port 2 pins they are pulled high by the internal
pull-ups and can be used as inputs. As inputs, Port 2 pins that are
externally being pulled low will source current (IIL) because of the
internal pull-ups.
Port 2 emits the high-order address byte during fetches from
external program memory and during accesses to external data memory
that uses 16-bit addresses (MOVX @ DPTR). In this application it uses
strong internal pull-ups when emitting 1s. During accesses to external
data memory that uses 8-bit addresses (MOVX @ RI), Port 2 emits the
contents of the P2 Special Function Register. Port 2 also receives the
high-order address bits and some control signals during Flash
programming and verification.
Port 3
Port 3 is an 8-bit bidirectional I/O port with internal pull-ups from
pin 10 to 17. The Port 3 output buffers can sink / source four TTL
inputs. When 1s are written to Port 3 pins they are pulled high by the
internal pull-ups and can be used as inputs. As inputs, Port 3 pins
that are externally being pulled low will source current (IIL) because
of the pull-ups.
Port 3 also serves the functions of various special features of the
AT89C52 as listed below:
Table 2.1 Special Features of port3
Port 3 also receives some control signals for Flash programming
and programming verification.
RST
Pin 9 is the Reset input. It is active high. Upon applying a high
pulse to this pin, the microcontroller will reset and terminate all
activities. A high on this pin for two machine cycles while the oscillator is
running resets the device.
ALE/PROG
Address Latch is an output pin and is active high. Address Latch
Enable output pulse for latching the low byte of the address during
accesses to external memory. This pin is also the program pulse
input (PROG) during Flash programming. In normal operation ALE is
emitted at a constant rate of 1/6 the oscillator frequency, and may be
used for external timing or clocking purposes.
Note, however, that one ALE pulse is skipped during each access
to external Data Memory. If desired, ALE operation can be disabled
by setting bit 0 of SFR location 8EH. With the bit set, ALE is active
only during a MOVX or MOVC instruction. Otherwise, the pin is weakly
pulled high. Setting the ALE-disable bit has no effect if the
microcontroller is in external execution mode.
PSEN
Program Store Enable is the read strobe to external program
memory. When the AT89C52 is executing code from external program
memory, PSEN is activated twice each machine cycle, except that two
PSEN activations are skipped during each access to external data
memory.
EA/VPP
External Access Enable EA must be strapped to GND in order to
enable the device to fetch code from external program memory
locations starting at 0000H up to FFFFH. Note, however, that if lock bit 1
is programmed, EA will be internally latched on reset. EA should be
strapped to VCC for internal program executions. This pin also receives
the 12-volt programming enable voltage (VPP) during Flash
programming when 12-volt programming is selected.
XTAL1
Input to the inverting oscillator amplifier and input to the internal clock operating circuit.
XTAL2
Output from the inverting oscillator amplifier.
Oscillator Characteristics
XTAL1 and XTAL2 are the input and output, respectively, of an
inverting amplifier which can be configured for use as an on chip
oscillator, as shown in Figure 5.3. Either a quartz crystal or ceramic
resonator may be used. To drive the device from an external clock
source, XTAL2 should be left unconnected while XTAL1 is driven as
shown in Figure 5.4.
Figure 2.3 crystal connections
Figure 2.4 External Clock Drive Configuration
There are no requirements on the duty cycle of the external clock
signal, since the input to the internal clocking circuitry is through a
divide-by two flip-flop, but minimum and maximum voltage high and low
time specifications must be observed.
Idle Mode
In idle mode, the CPU puts itself to sleep while all the on-chip peripherals remain active. The mode is invoked by software. The content of the on-chip RAM and all the special functions registers remain unchanged during this mode. The idle mode can be terminated by any enabled interrupt or by a hardware reset. It should be noted that when idle is terminated by a hardware reset, the device normally resumes program execution, from where it left off, up to two machine cycles before the internal reset algorithm takes control.
On-chip hardware inhibits access to internal RAM in this event, but
access to the port pins is not inhibited. To eliminate the possibility of an
unexpected write to a port pin when Idle is terminated by reset, the
instruction following the one that invokes Idle should not be one that
writes to a port pin or to external memory.
Power down Mode
In the power down mode the oscillator is stopped, and the
instruction that invokes power down is the last instruction executed. The
on-chip RAM and Special Function Registers retain their values until the
power down mode is terminated. The only exit from power down is a
hardware reset. Reset redefines the SFRs but does not change the on-
chip RAM. The reset should not be activated before VCC is restored to its
normal operating level and must be held active long enough to allow the
oscillator to restart and stabilize.
Table 2.2 Status Of External Pins During Idle and Power
Down Mode
Program Memory Lock Bits
On the chip are three lock bits which can be left unprogrammed
(U) or can be programmed (P) to obtain the additional features listed in
the table 5.4. When lock bit 1 is programmed, the logic level at the EA
pin is sampled and latched during reset. If the device is powered up
without a reset, the latch initializes to a random value, and holds that
value until reset is activated. It is necessary that the latched value of EA
be in agreement with the current logic level at that pin in order for the
device to function properly.
Table 2.3 Lock Bit Protection Modes
TIMERS
Timer 0 and 1
Timer 0 and Timer 1 in the AT89C52 operate the same way as
Timer 0 and Timer 1 in the AT89C51.
Register pairs (TH0, TL1), (TH1, TL1) are the 16-bit counter
registers for timer/counters 0 and 1.
Timer 2
Timer 2 is a 16-bit Timer/Counter that can operate as either a
timer or an event counter. The type of operation is selected by bit C/T2
in the SFR T2CON. Timer 2 has three operating modes: capture, auto-
reload (up or down counting), and baud rate generator. The modes are
selected by bits in T2CON, as shown in Table 5.2. Timer 2 consists of two
8-bit registers, TH2 and TL2. In the Timer function, the TL2 register is
incremented every machine cycle. Since a machine cycle consists of 12
oscillator periods, the count rate is 1/12 of the oscillator frequency.
Table 2.4 Timer 2 Operating Modes
In the Counter function, the register is incremented in response to
a 1-to-0 transition at its corresponding external input pin, T2. In this
function, the external input is sampled during S5P2 of every machine
cycle. When the samples show a high in one cycle and a low in the next
cycle, the count is incremented. The new count value appears in the
register during S3P1 of the cycle following the one in which the
transition was detected. Since two machine cycles (24 oscillator periods)
are required to recognize a 1-to-0 transition, the maximum count rate is
1/24 of the oscillator frequency. To ensure that a given level is sampled
at least once before it changes, the level should be held for at least one
full machine cycle.
There are no restrictions on the duty cycle of external input
signal, but it should for at least one full machine to ensure that a given
level is sampled at least once before it changes.
Capture Mode
In the capture mode, two options are selected by bit EXEN2 in
T2CON. If EXEN2 = 0, Timer 2 is a 16-bit timer or counter which upon
overflow sets bit TF2 in T2CON.This bit can then be used to generate an
interrupt. IfEXEN2 = 1, Timer 2 performs the same operation, but a 1-to-
0 transition at external input T2EX also causes the current value in TH2
and TL2 to be captured into RCAP2H andRCAP2L, respectively. In
addition, the transition at T2EXcauses bit EXF2 in T2CON to be set. The
EXF2 bit, likeTF2, can generate an interrupt.
Auto-reload (Up or Down Counter)
Timer 2 can be programmed to count up or down when configured
in its 16-bit auto-reload mode. This feature is invoked by the DCEN
(Down Counter Enable) bit located in the SFR T2MOD (see Table 4). Upon
reset, the DCEN bit is set to 0 so that timer 2 will default to count up.
When DCEN is set, Timer 2 can count up or down, depending on the
value of the T2EX pin. Table2.5: T2MOD-Timer 2 Mode Control Register
Table2.6: T2CON-Timer/Counter2 Control Register
2.5 Interrupts
The AT89C52 has a total of six interrupt vectors: two external
interrupts (INT0 and INT1), three timer interrupts (Timers 0, 1, and 2),
and the serial port interrupt. These interrupts are all shown in Figure 2.5
Figure 2.5 Interrupts source
Each of these interrupt sources can be individually enabled or
disabled by setting or clearing a bit in Special Function Register IE. IE
also contains a global disable bit, EA, which disables all interrupts at
once.
Note that Table 5.3 shows that bit position IE.6 is unimplemented.
In the AT89C51, bit position IE.5 is also unimplemented. User software
should not write 1s to these bit positions, since they may be used in
future AT89 products.
Table 2.7 Interrupts Enable Register
Timer 2 interrupt is generated by the logical OR of bits TF2 and
EXF2 in register T2CON. Neither of these flags is cleared by hardware
when the service routine is vectored to. In fact, the service routine may
have to determine whether it was TF2 or EXF2 that generated the
interrupt, and that bit will have to be cleared in software.
The Timer 0 and Timer 1 flags, TF0 and TF1, are set at S5P2 of the
cycle in which the timers overflow. The values are then polled by the
circuitry in the next cycle. However, the Timer 2 flag, TF2, is set at S2P2
and is polled in the same cycle in which the timer overflows.
2.6 Special function registers:
Special function registers are the areas of memory that control
specific functionality of the 89c52 microcontroller.
a) Accumulator (0E0h)
As its name suggests, it is used to accumulate the results of large
no. of instructions. It can hold 8 bit values.
b) B register (oFoh)
The B register is very similar to accumulator. It may hold 8-bit
value. The B register is only used by MUL AB and DIV AB instructions. In
MUL AB the higher byte of the products gets stored in B register. In DIV
AB the quotient gets stored in B with the remainder in A.
c) Stack pointer (081h)
The stack pointer holds 8-bit value. This is used to indicate where
the next value to be removed from the stack should be taken from.
When a value is to be pushed on to the stack, the 8052 first store the
value of SP and then store the value at the resulting memory location.
When a value is to be popped from the stack, the 8052 returns the value
from the memory location indicated by SP and then decrements the
value of SP.
d) Data pointer (Data pointer low/high, address 82/83h)
The SFRs DPL and DPH work together to represent a 16-bit value
called the data pointer. The data pointer is used in operations regarding
external RAM and some instructions code memory. It is a 16-bit SFR and
also an addressable SFR.
e) Program counter
The program counter is a 16 bit register, which contains the 2
byte address, which tells the next instruction to execute to be found in
memory. When the 8052 is initialized PC starts at 0000h and is
incremented each time an instruction is executes. It is not addressable
SFR.
f) PCON (power control, 87h)
The power control SFR is used to control the 8052’s power control
modes. Certain operation modes of the 8052 allow the 8052 to go into a
type of “sleep mode” which consumes low power.
g)TCON(Timer control, 88h)
The timer mode control SFR is used to configure and modify the
way in which the 8052’s two timers operate. This SFR controls whether
each of the two timers is running or stopped and contains a flag to
indicate that each timer has overflowed. Additionally, some non-timer
related bits are located in TCON SER. These bits are used to configure
the way in which the external interrupt flags are activated, which are set
when an external interrupt occur.
h)TMOD(Timer Mode,89h)
The timer mode SFR is used to configure the mode of operation of
each of the two timers. Using this SR your program may configure each
timer to be a 16-bit timer, or 13 bit timer, 8-bit auto reload timer, or two
separate timers. Additionally you may configure the timers to only count
when an external pin is activated or to count “events” that are indicated
on an external pin.
TIMER1 TIMER0
i) T0 (Timer 0 low/ high, address 8A/ 8C h)
SMOD ---- --- ---- GF1 GF0
PD IDL
TF1 TR1 TF0 TR0 IE1 IT1 IE0 IT0
Gate
C/ T M1 M0 Gate
C/ T M1 M0
These two SFRs together represent timer 0. Their exact behavior
depends on how the timer is configured in the TMOD SFR; however,
these timers always count up. What is configurable is how and when
they increment value.
j) T1 (Timer 1 low/ high, address 8B/ 8D h)
These two SFRs together represent timer 1. Their exact behavior
depends on how the timer is configured in the TMOD SFR; however,
these timers always count up. What is configurable is how and when
they increment in value.
k) P0 (Port 0, address 80h, bit addressable)
This is port 0 latch. Each bit of this SFR corresponds to one of the
pins on a micro controller. Any data to be outputted to port 0 is first
written on P0 register. For e.g., bit 0 of port 0 is pin P0.0, bit 7 is pin
P0.7. Writing a value of 1 to a bit of this SFR will send a high level on the
corresponding I/O pin whereas a value of 0 will bring it to low level.
l) P1(Port 1, address 90h, bit addressable)
This is port 1 latch. Each bit of this SFR corresponds to one of the
pins on a micro controller. Any data to be outputted to port 1 is first
written on P1 register. For e.g., bit 0 of port 1 is pin P1.0, bit 7 is pin
P1.7. Writing a value of 1 to a bit of this SFR will send a high level on the
corresponding I/O pin whereas a value of 0 will bring it to low level.
m) P2 (Port 2, address 0A0h, bit addressable)
This is port 2 latch. Each bit of this SFR corresponds to one of the
pins on a micro controller. Any data to be outputted to port 2 is first
written on P2 register. For e.g., bit 0 of port 2 is pin P2.0, bit 7 is pin
P2.7. Writing a value of 1 to a bit of this SFR will send a high level on the
corresponding I/O pin whereas a value of 0 will bring it to low level.
n) P3 (Port 3, address 0B0h, bit addressable)
This is port 3 latch. Each bit of this SFR corresponds to one of the
pins on a micro controller. Any data to be outputted to port 3 is first
written on P3 register. For e.g., bit 0 of port 3 is pin P3.0, bit 7 is pin
P3.7. Writing a value of 1 to a bit of this SFR will send a high level on the
corresponding I/O pin whereas a value of 0 will bring it to low level.
o) IE (Interrupt Enable, 0A8h)
The interrupt enable SFR is used to enable and disable specific interrupts. The low
7 bits of the SFR are used to enable/disable the specific interrupts, where the MSB bit is
used to enable or disable all the interrupts. Thus, if the high bit of IE 0 all interrupts are
disabled regardless of whether an individual interrupt is enabled by setting a lower bit.
EA _ _ _
ET2 ES ET1 EX1 ET0 EX0
p) IP (Interrupt Priority, 0B8h)
The interrupt priority SFR is used to specify the relative priority of each interrupt.
On 8052, an interrupt may be either low or high priority. An interrupt may interrupt
interrupts. For e.g., if we configure all interrupts as low priority other than serial interrupt.
The serial interrupt always interrupts the system; even if another interrupt is currently
executing no other interrupt will be able to interrupt the serial interrupt routine since the
serial interrupt routine has the highest priority.
_ _ _ _ _ _ PT2 PS PT1 PX1 PT0 PX0
q)PSW (Program Status Word, 0D0h)
The Program Status Word is used to store a number of important
bits that are set and cleared by 8052 instructions. The PSW SFR contains
the carry flag, the auxiliary carry flag, the parity flag and the overflow
flag. Additionally, it also contains the register bank select flags, which
are used to select, which of the “R” register banks currently in use.
r) SBUF (Serial Buffer, 99h)
SBUF is used to hold data in serial communication. It is physically
two registers. One is writing only and is used to hold data to be
transmitted out of 8052 via TXD. The other is read only and holds
received data from external sources via RXD. Both mutually exclusive
registers use address 99h.S
2.7 Memory Organization
The total memory of 89C52 system is logically divided in Program
memory and Data memory. Program memory stores the programs to be
executed, while data memory stores the data like intermediate results,
variables and constants required for the execution of the program.
Program memory is invariably implemented using EPROM, because it
stores only program code which is to be executed and thus it need not
be written into. However, the data memory may be read from or written
to and thus it is implemented using RAM.
Further, the program memory and data memory both may be
categorized as on-chip (internal) and external memory, depending upon
whether the memory physically exists on the chip or it is externally
interfaced. The 89C52 can address 8Kbytes on-chip memory whose map
starts from 0000H and ends at 1FFFH. It can address 64Kbytes of
external program memory under the control of PSEN (low) signal.
The AT89C52 implements 256 bytes of on-chip RAM. The upper
128 bytes occupy a parallel address space to the Special Function
Registers. That means the upper 128bytes have the same addresses as
the SFR space but are physically separate from SFR space. When an
instruction accesses an internal location above address 7FH, the address
mode used in the instruction specifies whether the CPU accesses the
CY AC F0 RS1 RS0 OV - - - - P
upper 128 bytes of RAM or the SFR space. Instructions that use direct
addressing access SFR space. For example, the following direct
addressing instruction accesses the SFR at location 0A0H (which is P2).
MOV 0A0H, #data
Instructions that use indirect addressing access the upper128
bytes of RAM. For example, the following indirect addressing instruction,
where R0 contains 0A0H, accesses the data byte at address 0A0H,
rather than P2 (whose address is 0A0H)
.MOV @R0, #data
Note that stack operations are examples of indirect addressing, so the
upper 128 bytes of data RAM are available as stack space.
7. REGULATED POWER SUPPLY
7.1 Description:
A variable regulated power supply, also called a
variable bench power supply, is one where you can continuously
adjust the output voltage to your requirements. Varying the output
of the power supply is the recommended way to test a project
after having double checked parts placement against circuit
drawings and the parts placement guide. This type of regulation is
ideal for having a simple variable bench power supply. Actually
this is quite important because one of the first projects a hobbyist
should undertake is the construction of a variable regulated power
supply. While a dedicated supply is quite handy e.g. 5V or 12V, it's
much handier to have a variable supply on hand, especially for
testing. Most digital logic circuits and processors need a 5 volt
power supply. To use these parts we need to build a regulated 5
volt source. Usually you start with an unregulated power supply
ranging from 9 volts to 24 volts DC (A 12 volt power supply is
included with the Beginner Kit and the Microcontroller Beginner
Kit.). To make a 5 volt power supply, we use a LM7805 voltage
regulator IC .
The LM7805 is simple to use. You simply connect the
positive lead of your unregulated DC power supply (anything from
9VDC to 24VDC) to the Input pin, connect the negative lead to the
Common pin and then when you turn on the power, you get a 5
volt supply from the Output pin.
Circuit Features:
Brief description of operation: Gives out well regulated +5V
output, output current capability of 100 mA
Circuit protection: Built-in overheating protection shuts
down output when regulator IC gets too hot
Circuit complexity: Very simple and easy to build
Circuit performance: Very stable +5V output voltage,
reliable operation
Availability of components: Easy to get, uses only very
common basic components
Design testing: Based on datasheet example circuit, I have
used this circuit successfully as part of many electronics projects
Applications: Part of electronics devices, small laboratory
power supply
Power supply voltage: Unregulated DC 8-18V power supply
Power supply current: Needed output current + 5 mA
Component costs: Few dollars for the electronics
components + the input transformer cost
7.2 Block Diagram:
7.3 Circuit Diagram:
Basic Power Supply Circuit:
Above is the circuit of a basic unregulated dc power supply. A
bridge rectifier D1 to D4 rectifies the ac from the transformer secondary,
which may also be a block rectifier such as WO4 or even four individual
diodes such as 1N4004 types. (See later re rectifier ratings).
The principal advantage of a bridge rectifier is you do not need a
centre tap on the secondary of the transformer. A further but significant
advantage is that the ripple frequency at the output is twice the line
frequency (i.e. 50 Hz or 60 Hz) and makes filtering somewhat easier.
As a design example consider we wanted a small unregulated
bench supply for our projects. Here we will go for a voltage of about 12 -
13V at a maximum output current (IL) of 500ma (0.5A). Maximum ripple
will be 2.5% and load regulation is 5%.
Now the RMS secondary voltage (primary is whatever is consistent
with your area) for our power transformer T1 must be our desired output
Vo PLUS the voltage drops across D2 and D4 (2 * 0.7V) divided by 1.414.
This means that Vsec = [13V + 1.4V] / 1.414 which equals about 10.2V.
Depending on the VA rating of your transformer, the secondary voltage
will vary considerably in accordance with the applied load. The
secondary voltage on a transformer advertised as say 20VA will be much
greater if the secondary is only lightly loaded.
If we accept the 2.5% ripple as adequate for our purposes then at
13V this becomes 13 * 0.025 = 0.325 Vrms. The peak to peak value is
2.828 times this value. Vrip = 0.325V X 2.828 = 0.92 V and this value is
required to calculate the value of C1. Also required for this calculation is
the time interval for charging pulses. If you are on a 60Hz system it it 1/
(2 * 60) = 0.008333 which is 8.33 milliseconds. For a 50Hz system it is
0.01 sec or 10 milliseconds.
Remember the tolerance of the type of capacitor used here is
very loose. The important thing to be aware of is the voltage rating
should be at least 13V X 1.414 or 18.33. Here you would use at least the
standard 25V or higher (absolutely not 16V).With our rectifier diodes or
bridge they should have a PIV rating of 2.828 times the Vsec or at least
29V. Don't search for this rating because it doesn't exist. Use the next
highest standard or even higher. The current rating should be at least
twice the load current maximum i.e. 2 X 0.5A or 1A. A good type to use
would be 1N4004, 1N4006 or 1N4008 types.
These are rated 1 Amp at 400PIV, 600PIV and 1000PIV
respectively. Always be on the lookout for the higher voltage ones when
they are on special.
7.4 IC Voltage Regulators:
Voltage regulators comprise a class of widely used ICs.
Regulator IC units contain the circuitry for reference source,
comparator amplifier, control device, and overload protection all in
a single IC. Although the internal construction of the IC is
somewhat different from that described for discrete voltage
regulator circuits, the external operation is much the same. IC
units provide regulation of either a fixed positive voltage, a fixed
negative voltage, or an adjustably set voltage.
A power supply can be built using a transformer connected to the
ac supply line to step the ac voltage to desired amplitude, then
rectifying that ac voltage, filtering with a capacitor and RC filter, if
desired, and finally regulating the dc voltage using an IC regulator. The
regulators can be selected for operation with load currents from
hundreds of mill amperes to tens of amperes, corresponding to power
ratings from mill watts to tens of watts.
Three-Terminal Voltage Regulators:
Fixed Positive Voltage Regulators:
Vin
Vout
C1 C2
Fig shows the basic connection of a three-terminal voltage
regulator IC to a load. The fixed voltage regulator has an
unregulated dc input voltage, Vi, applied to one input terminal, a
regulated output dc voltage, Vo, from a second terminal, with the
third terminal connected to ground. While the input voltage may
vary over some permissible voltage range, and the output load
may vary over some acceptable range, the output voltage remains
constant within specified voltage variation limits. A table of
positive voltage regulated ICs is provided in table. For a selected
regulator, IC device specifications list a voltage range over which
the input voltage can vary to maintain a regulated output voltage
IN OUT
78XX
GND
over a range of load current. The specifications also list the
amount of output voltage change resulting from a change in load
current (load regulation) or in input voltage (line regulation).
TABLE: Positive Voltage Regulators in 7800 series
IC No. Output voltage(v) Maximum input voltage(v)
7805
7806
7808
7810
7812
7815
7818
7824
+5
+6
+8
+10
+12
+15
+18
+24
35V
40V
RF Receiver Module - RX433Remote Control Products
RF Receiver Module RX433
Click these images for a larger view.
This compact radio frequency (RF) receiver module is suitable for remote control or
telemetry applications. The double sided circuit board is pre-populated with Surface
Mount Devices (SMD) and is tuned to 433MHz. No module assembly or
adjustments are required. RF receiver module RX433 receives RF control signals
from the 8 channel RF remote control transmitter K8058 and performs as an RF
receiver interface when used on the 8 channel remote control relay board K8056.
(Only one RX433 RF receiver is needed for full RF remote control operation of the
8 channel relay board K8056). RF receiver module RX433 is a highly sensitive
passive design that is easy to implement with a low external parts count. (Download
datasheet with hook-up schematic below)
RF remote receiver module RX433 can also be used with 433MHz RF Transmitter
TX433N for your custom remote control or telemetry requirements. (However, the
FCC has restrictions on the sale of the TX433N transmitter module in the U.S., so
we don't have these transmitters available).
RF Receiver Module Features
no RF receiver module adjustments required
stable output
suitable for RF remote controls, telemetry, ...
Specifications
RF receiver frequency: 433MHz
receiver range: 220 yards (200m) in open air
modulation: AM
modulate mode: ASK
circuit shape: LC
sensitivity: 3µVrms
power supply: 4.5 - 5.5V DC
data rate: 4800 bps
receiver selectivity: -106 dB
channel spacing: 1 MHz
digital and linear output
RF receiver module pin numbers
o 1: gnd
o 2: digital output
o 3: linear output
o 4: Vcc
o 5: Vcc
o 6: gnd
o 7: gnd
o 8: antenna: 11.8" - 13.77" (30cm - 35cm)
TX433: 433MHz Transmitter Module
VIEW LARGER
IMAGE
Modulation : AM
RF output : 8mW
Power supply : 3 - 12Vdc
Power Supply and All Input /
Output Pins: -0.3 to +12.0 V
*Non-Operating Case Temperature: -20 to +85
*Soldering Temperature ( 10 Seconds ) : 230 ( 10 Seconds )
Features
no adjustments required
stable output
suitable for remote controls, telemetry, ..Specifications
frequency : 433MHz
modulation : AM
RF output : 8mW
power supply : 3 - 12Vdc
Circuit Shape: SAW
Data Rate: 8 kbps
pin numbers :
1 : GND
2 : Data_IN
3 : Vcc
4 : ANTLCD:- To send any of the commands from given
table to the lcd, make pin RS =0.For data, make RS=1.then send a
high to low pulse to the E pin to enable the internal latch of the
LCD. As shown in figure for LCD connections.
Pin number
Symbol Level I/O Function
1 Vss - - Power supply (GND)
2 Vcc - - Power supply (+5V)
3 Vee - - Contrast adjust
4 RS 0/1 I0 = Instruction input1 = Data input
Pin number
Symbol Level I/O Function
5 R/W 0/1 I0 = Write to LCD module1 = Read from LCD module
6 E 1, 1->0 I Enable signal
7 DB0 0/1 I/O Data bus line 0 (LSB)
8 DB1 0/1 I/O Data bus line 1
9 DB2 0/1 I/O Data bus line 2
10 DB3 0/1 I/O Data bus line 3
11 DB4 0/1 I/O Data bus line 4
12 DB5 0/1 I/O Data bus line 5
13 DB6 0/1 I/O Data bus line 6
14 DB7 0/1 I/O Data bus line 7 (MSB)
Table 2.2., Pin assignment for > 80 character displays
Pin number
Symbol Level I/O Function
1 DB7 0/1 I/O Data bus line 7 (MSB)
2 DB6 0/1 I/O Data bus line 6
3 DB5 0/1 I/O Data bus line 5
4 DB4 0/1 I/O Data bus line 4
Table 2.2., Pin assignment for > 80 character displays
Pin number
Symbol Level I/O Function
5 DB3 0/1 I/O Data bus line 3
6 DB2 0/1 I/O Data bus line 2
7 DB1 0/1 I/O Data bus line 1
8 DB0 0/1 I/O Data bus line 0 (LSB)
9 E1 1, 1->0 IEnable signal row 0 & 1 (1stcontroller)
10 R/W 0/1 I0 = Write to LCD module1 = Read from LCD module
11 RS 0/1 I0 = Instruction input1 = Data input
12 Vee - - Contrast adjust
13 Vss - - Power supply (GND)
14 Vcc - - Power supply (+5V)
15 E2 1, 1->0 IEnable signal row 2 & 3 (2ndcontroller)
16 n.c.
Table 2.4. Bit names
Bit name
Setting / Status
I/D 0 = Decrement cursor position1 = Increment cursor position
S 0 = No display shift 1 = Display shift
Table 2.2., Pin assignment for > 80 character displays
Pin number
Symbol Level I/O Function
D 0 = Display off 1 = Display on
C 0 = Cursor off 1 = Cursor on
B 0 = Cursor blink off1 = Cursor blink on
S/C 0 = Move cursor 1 = Shift display
R/L 0 = Shift left 1 = Shift right
DL 0 = 4-bit interface 1 = 8-bit interface
N 0 = 1/8 or 1/11 Duty (1 line)1 = 1/16 Duty (2 lines)
F 0 = 5x7 dots 1 = 5x10 dots
BF 0 = Can accept instruction1 = Internal operation in progress
KEIL SOFTWARESOFTWARE DESCRIPTION:Click on the Keil uVision Icon on Desktop
1. The following fig will appear
2. Click on the Project menu from the title bar
3. Then Click on New Project
4. Save the Project by typing suitable project name with no extension in u r own
folder sited in either C:\ or D:\
5. Then Click on Save button above.
6. Select the component for u r project. i.e. Atmel……
7. Click on the + Symbol beside of Atmel
8. Select AT89C51 as shown below
9. Then Click on “OK”
10. The Following fig will appear
11. Then Click either YES or NO………mostly “NO”
12. Now your project is ready to USE
13. Now double click on the Target1, you would get another option “Source group
1” as shown in next page.
14. Click on the file option from menu bar and select “new”
15. The next screen will be as shown in next page, and just maximize it by double
clicking on its blue boarder.
16. Now start writing program in either in “C” or “ASM”
17. 99For a program written in Assembly, then save it with extension “. asm” and
for “C” based program save it with extension “ .C”
18. Now right click on Source group 1 and click on “Add files to Group
Source”
19. Now you will get another window, on which by default “C” files will
appear.
20. Now select as per your file extension given while saving the file
21. Click only one time on option “ADD”
22. Now Press function key F7 to compile. Any error will appear if so
happen.
23. If the file contains no error, then press Control+F5 simultaneously.
24. The new window is as follows
25. Then Click “OK”
26. Now Click on the Peripherals from menu bar, and check your required
port as shown in fig below
27. Drag the port a side and click in the program file.
28. Now keep Pressing function key “F11” slowly and observe.
You are running your program successfully
CONCLUSION
Embedded systems are emerging as a technology with high potential. In the past
decades micro processor based embedded system ruled the market. The last decade
witnessed the revolution of Microcontroller based embedded systems. This project
basically deals with how many number of persons are in the room very accurately with the
help of Microcontroller. With regards to the requirements gathered the manual work and
the complexity in counting can be achieved with the help of electronic devices.
FUTURE SCOPE
This system is a rapidly growing field and there are new and improved
strategies popping up all the time. For the most part these systems are all built around the
same basic structure, a central box that monitors several detectors and perimeter guards
and sounds an alarm when any of them are triggered.
This system is best for guiding the perimeter of a house or a business center
the points where an intruder would enter the building. In this system IR sensor is used to
detect the intrusion. Similarly the vibration and temperature sensors recognize vibration
disturbances and accidental fires respectively.
This project provides an efficient and economical security system. This
system finds applications in industries, banks and homes.
Incorporating the features discussed below can further enhance the system
This system can detect intrusion only at discrete points. This system
detection feature can be extended to scanning a complete area. Thus the
intrusion into the building can be detected with much more efficiently.
The redialing feature can also be incorporated such that if the call is not put
forward the first time, the auto dialer will dial the same number until the call
is successfully completed.
A pre-recorded voice message can delivered to the owner notifying him about
the intrusion into the premises.
The addition of the above discussed advancements certainly builds this
project into a much flexible and reliable security system.
REFERENCES
1. The 8051 Microcontroller and Embedded Systems By Muhammad Ali Mazidi
2. Fundamentals Of Embedded Software By Daniel W Lewis
3..www.howsstuffworks.com
4. www.alldatasheets.com
5. www.electronicsforu.com
6. www.knowledgebase.com
7.www.8051 projectsinfo.com
8.Datasheets of Microcontroller AT89C52
9. Datasheets of 555 timer
10. Datasheets of TSAL 6200
11. Datasheets of TSOP 1356
12. Datasheets of BC 547