2. why this project ?
The present days many houses are secure less
and all appliances are operated manually.
The objective of this project is to enable users to
remotely control their home appliances and
systems using a cell phone-based interface via a
simple SMS .
Over the last decade, this problem has been
overcome by using the Internet and through
power-line modems.
3. DESCRIPTION
TRANSMITTING END
ANY TYPE OF CELL PHONE THAT CAN SEND AND
RECEIVE SMS.(GSM/CDMA)
RECEIVING END
“GSM” CELLPHONE SUPPORTING BASIC AT
COMMANDS
MICROCONTROLLER
MAX 232
RS232 INTERFACE
POWER SUPPLY
VOLTAGE REGULATOR
RELAYS
KEYPAD AND LCD DISPLAY
4. Wireless?
Rf?
Short range
Signal get weaken
Ir?
Short range
Straight path
Bluetooth?
Short range
No authentication
5. Wireless?
Wifi?
Need of hot spots
Internet connection
a separate dedicated system
Expensive
6. Wireless - GSM
Global system of mobile communication
Available in all parts of the world
No distance limit
Needs only a dedicated GSM cellphone
and a interface cable
Minimum power consumption
Not expensive
Because we use the SMS for communicating
7. controller?
A PC?
Expensive
Power consumption is more
A Microprocessor?
Needs External RAM,TIMER,ROM…..
Serial Interfacing is difficult
A FPGA?
Expensive
Programming is difficult
8. A Microcontoller
It has in built RAM,ROM,TIMER….
Serial interfacing is easy
Programming is easy
Power consumption is minimum
cheap
Does not occupy much space
9. SOFTWARE
LABview?
Very expensive
Need of external interfacing device ,DAC
and a PC.
PLC
Expensive
It has only 8 i/o ports
10. KEIL
This software is used to program the
microcontroller
This software uses “C”compiler.
Easy programming
Not expensive (freeware is available)
Needs only a programmer (to burn a
ROM)
11. PROJECT
DESCRIPTION
ATMEL MICROCONTROLLER SERIES:
89C51 Family
TECHNOLOGY: CMOS
FEATURES:
4K Bytes of In-System Reprogrammable Flash Memory
Fully Static Operation: 0 Hz to 24 MHz
Three-Level Program Memory Lock
128 x 8-Bit Internal RAM
32 Programmable I/O Lines
Two 16-Bit Timer/Counters
Six Interrupt Sources
Programmable Serial Channel
Low Power Idle and Power Down Modes
12. MAX232
It is a dual driver/receiver.
A capacitive voltage generator to supply RS-232
voltage levels from a single 5-V supply.
Each receiver converts RS-232 inputs to 5-V
TTL/CMOS levels.
Each driver converts TTL/CMOS input levels into
EIA-232 levels.
This chip is used to do the level shifting & it is
required to send data serially to a cell phone which
requires voltage levels as per RS232 standard.
13. RS232 STANDARD
RS232 is an interface cable used for serial
communication.
9-pin (DB9) connector cable.
Voltage level:
+12v(logic 0)
-12v(logic1)
the signal encoding used here is NRZ-L
It uses only two levels.
14. AT COMMANDS
A GSM cellphone is a wireless modem
The instructions used for controlling the mobile
phone or GSM/GPRS modem are called AT
commands.
One use of the AT commands is to control the
sending and receiving of SMS messages.
16. Important AT command
ATD To dial a voice call from the modem.
AT+CLIR For calling line Identification Restriction.
AT+CNMI To set the mode of the mobile.
AT+CMGR To read the message at particular
location.
AT+CMGD To delete the received message
AT+CMGS To send the message.
AT+CMGF To change the message format to PDU
or Text mode.
AT+CMGL To see all the list of messages.
17. WORKING:
STEP1: the command AT is sent through the microcontroller from SBUF register.
STEP2: “AT+CMGF=1” is sent to set the mobile phone in text mode.
STEP3: AT+CPMS=”ME” command selects the phone memory.
STEP4: AT+CNMI=1,2,0,0,0 this command will read the message in the first index of the
phone memory and delete it after reading it.
STEP5: when a new message says “HEATER ON” is sent from our mobile this is
delivered to the microcontroller directly in this text format.
+CMGL:1,"RECREAD","+85291234567",,"06/11/11,00:30:29+32"
HEATER ON.
STEP6: SBUF register will receive this message. Through our
program the carriage return is sensed and the content of the message
is received.
STEP7: this string received is compared with the already stored string. If this match occurs
the corresponding subroutine is invoked and the corresponding port pin is made “1”.
STEP8: this port is connected to a relay and through this the HEATER is switched ON.
18. SECURITY SYSTEMS
The security system that is used includes an electronic
keypad that comprises of 8 keys numbering (0-7).
In the residence absence, When a person enters/types
the home code . This code will be sent to the owner’s
cell phone number through the microcontroller.
If the code is correct command “OPEN DOOR” is sent.
The microcontroller will interpret this command and
opens the door. If the code is wrong the door will not
be opened.
All the above authentication process is done by
separate subroutine in our program. This subroutine is
invoked when the keypad is activated.
20. FUTURE ENHANCEMENT
CONTROL ENHANCEMENT:
Timer control:
○ Immersion Heater:
A timer in microcontroller is used to set the time after it gets
switched off.
○ Motor Pump
After a period of time, the motor gets switched off & sends a
message like "motor is switched off, tank is filled. “
Parameter control:
○ Temperature setting in a heater
○ Setting temperature in air conditioners:
Sensing the temperature, convert into digital signals and using
8255 PPI send info to 89c51.
21. SECURITY ENHANCEMENT
Sensors:
○ When a moving object is sensed, all the hidden cameras would get
switched ON.
Hidden Cameras:
○ Taking photographs & sending via MMS.
Energy Meter:
○ When speed of rotation exceeds, it will intimate certain devices to turn
OFF.
Sound Meter:
○ When a sound is sensed, it would send message.