When you press key ‘2’ (binary equivalent 00000010) on your mobile phone, the microcontroller outputs ‘10001001’ binary equivalent. According to the program in the microcontroller, the robot starts moving. The MT8870 decodes the received tone and sends the equivalent binary number to the microcontroller. These tones are fed to the circuit by the headset of the cellphone. The DTMF tones thus produced are received by the cellphone in the robot. Now you may press any button on your mobile to perform actions as listed in Table III. (If the mobile does not have the auto answering facility, receive the call by ‘OK’ key on the rover-connected mobile and then made it in hands-free mode.) So after a ring, the cellphone accepts the call. The cell phone in the robot is kept in ‘auto answer’ mode. In order to control the robot, you need to make a call to the cell phone attached to the robot (through head phone) from any phone, which sends DTMF tunes on pressing the numeric buttons. The corresponding data will output at port D after testing of the received data. Under ‘while’ loop, read port A and test the received input using ‘switch’ statement. The program will run forever by using ‘while’ loop. Set port A as the input and port D as the output. First include the register name defined specifically for ATmega16 and also declare the variable. The source program is well commented and easy to understand.
Burn this hex code into ATmega16 AVR microcontroller. The source program is converted into hex code by the compiler.
The software is written in ‘C’ language and compiled using CodeVision AVR ‘C’ compiler.
Similarly, enable input EN2 (pin 9) enables drivers 3 and 4. When enable input EN1 (pin 1) is high, drivers 1 and 2 are enabled and the outputs corresponding to their inputs are active. Drivers 1 and 2, and drivers 3 and 4 are enabled by enable pin 1 (EN1) and pin 9 (EN2), respectively.
Pins IN1 through IN4 and OUT1 through OUT4 are input and output pins, respectively, of driver 1 through driver 4. It makes it easier to drive the DC motors. The L293D is a quad, high-current, half-H driver designed to provide bidirectional drive currents of up to 600 mA at voltages from 4.5V to 36V. The tones and assignments in a DTMF system are shown in Table I. The signal generated by the DTMF encoder is a direct algebraic summation, in real time, of the amplitudes of two sine (cosine) waves of different frequencies, i.e., pressing ‘5’ will send a tone made by adding 1336 Hz and 770 Hz to the other end of the line. The version of DTMF used for telephone tone dialing is known as ‘Touch-Tone.’ĭTMF assigns a specific frequency (consisting of two separate tones) to each key so that it can easily be identified by the electronic circuit. So this simple robotic project does not require the construction of receiver and transmitter units.ĭTMF signaling is used for telephone signaling over the line in the voice- frequency band to the call switching center. The mobile that makes a call to the mobile phone stacked in the robot acts as a remote. The microcontroller is preprogrammed to take a decision for any given input and outputs its decision to motor drivers in order to drive the motors for forward or backward motion or a turn. The decoder decodes the DTMF tone into its equivalent binary digit and this binary number is sent to the microcontroller. The received tone is processed by the ATmega16 microcontroller with the help of DTMF decoder MT8870. The robot perceives this DTMF tone with the help of the phone stacked in the robot. This tone is called ‘dual-tone multiple-frequency’ (DTMF) tone. In the course of a call, if any button is pressed, a tone corresponding to the button pressed is heard at the other end of the call. In this project, the robot is controlled by a mobile phone that makes a call to the mobile phone attached to the robot. Generally, the preceptors are sensors mounted on the robot, processing is done by the on-board microcontroller or processor, and the task (action) is performed using motors or with some other actuators. The control of robot involves three distinct phases: perception, processing and action. It provides the advantages of robust control, working range as large as the coverage area of the service provider, no interference with other controllers and up to twelve controls.Īlthough the appearance and capabilities of robots vary vastly, all robots share the features of a mechanical, movable structure under some form of control. Use of a mobile phone for robotic control can overcome these limitations. Conventionally, wireless-controlled robots use RF circuits, which have the drawbacks of limited working range, limited frequency range and limited control.