Codelock with dialup(8051)

Codelock with dialup(8051)

More and more devices are coming every day to protect your house and property from thiefs .Present project is also one of them. The project presented here is based on world’ s most powerful intel’ s mcs-51 family of microcontroller atmel at89c51. When ever somebody tries to open your latch by entering wrong numbers. After three wrong retries. The project takes the following action 1) Sounds an siron to attract your or public attention . 2) It will call a telephone number you wanted the device should call you in such case. 3) I will make 5 attempts to call you at the interval of one second and deliver the emergency message stored in speech ic. 4) During this operation the key board will get lock and will not except any key press. 5) Key lock will be indicated by an led LD4 connected on top of kaypad, will glow permanently till the time keypad is lock. 6) Key pad will get unlock only after 5 retries of the phone. The project comprises of the following blocks: · Microcontroller · Password store key · Telephone store key · Indication leds · 4x3 matrix key pad · serial eprom to store the password and telephone number. · Speech circuit · Amplifier circuit · Off-hook circuit · Dialer circuit · Latch relay · Power supply key1 to store the password key2 to store the telephone number LD4 Code acceptance led LD3 Telephone number stored confirmation key LD2 Password stored confirmation key. C4 and r2 gives desired reset pulse on microcontroller pin 9. Crystal oscillator x1 along with capacitor c5 & c6 gives required clock to microcontroller. 7) Ic 4 is a one time programmable(otp) chip where messages are stored. This is 20 seconds speech ic where total of eight messages can be recorded on eight different locations but total duration should not be more than 20 seconds recorded messages can be played back by setting the trigger pin 10,11 high, making these pin low will stop the message, repeatedly Setting these pin high will repeatedly replay the same message. Ic5 is an audio amplifire . Audio output from speech ic pin no 7 cout is coupled to this ic on pin no 3 through vr2 volume control and c10. Amplified output from pin no 5 drives thespeaker through capacitor c14. R10 and c13 corrects the tone. R8 and c9 provides decoupling and tone correction . This audio output at capacitor is also given to telephone matching and isolation transformer T1 ,to send the sound over telephone lines. Ic4 works on 3.7v so r11 is drops the excessive voltage before it is given to the pin number 9 and 12 of this ic. D7 is 3.7 v zener diode for the protection circuit c7 is a filter capacitor. C8 is a feed back capacitor r9 along with vr1 performs the sampling rate adjustment. Vr2 is a volume control c11 and c12 are filter capacitors. Diode d9 and d10 connected to the secondary of the matching transformer t1 are to maintain the empedence balance. Ic3 is a serial eprom ic where password and telephone numbers are stored.this ic retain the password even during the absence of power supply. Capacitor c16 and c17 are filter capacitors. K1 relay is a telephone number dialer relay operated by transister Q1. K2 is a off hook relay operated by transister Q2. K3 is a latch relay operated by transister Q3. ...........