Cell Phone controlled Land Rover using AT89S52 is basically made to operate robots by cell phone in order to simplify the control of robots. It is mainly focused to overcome the limited working range of wireless controlled robots which uses RF circuit. Cell phone controlled robot provides the advantages of robust control and increases the working range as large as the coverage area of the service provider. There is no any interference with other controllers and give up to twelve controls. It enables you to control the your robot only by pressing of your mobile key from anywhere just like that your cell phone works as remote control. Although, the Cell phone controlled robot’s appearance and capabilities vary vastly. In spite of the fact all robots share the feature of a mechanical, movables structure under some form of control.
In our Cell Phone Controlled Robot, there is circuit containing micro – controller AT89S52 which is the heart of the circuit. It is high performance, low power, 8 bit micro- controller with 4 KB of flash programmable and erasable read only memory used as on- chip program memory. An 11.0592MHz crystal oscillator is used to provide basic clock frequency for micro- controller. A push to on switch connected between pin no. 9 of controller and VCC is used for manual reset of circuit.
The DTMF (Dual-tone multi-frequency) decode MT8870 is connected the micro- controller. It is used for decoding the mobile signal. It gets DTMF tone from the mobile headphone and decodes it into 4 bit digital signal.
There is a mobile phone say MB1 that makes a call to other mobile phone say MB2 which is attached to the robot to control it. After making a call, the mobile phone MB2 automatically receives the call and wait for another instruction. Now administrator has to press the key of mobile phone MB1 according to our define for each operation of robot. The mobile phone MB2 receives the ‘Dual Tone Multiple frequency’ (DTMF) tone by headphone and proceeds it to the circuit attach with it. Now, the received tone is processed by the micro – controller with the help of DTMF decoder IC MT8870 and checks it with our defined function saved in its memory. According to operation has to be done, micro -controller sends a signals to the motor driver IC L293D which drives the motor. And with the help of motors the robot move Forward, Reverse, Left, Right or Stop.