Introduction: DTMF BASED OBSTACLE AVOIDER ROBOT

it is based on DTMF TECHNOLOGY, by which your car responds to the low and high frequency of the number u pressed in your mobile phone, After giving a ring,

Step 1: BLOCK DIAGRAM

THE WORKING PRINCIPLE BEHIND THE PROJECT IS ILLUSTRATED IN THE BLOCK DIAGRAM,

Step 2: GETTING STARTED WITH THE ARDUINO BOARD

THE ARDUINO BOARD IS THE GREAT OF THE CIRCUIT, AS ALL THE NECESSARY PROGRAMS ARE FEEDED INTO THIS BOARD AND IT MAKES AN CONTROL OVER THE ALL,

The ATmega328 is a single chip micro-controller created by Atmel and belongs to the megaAVR series. The ATmega328P is a low-power CMOS 8-bit microcontroller based on the AVR enhanced RISC architecture. By executing powerful instructions in a single clock cycle, the ATmega328P achieves throughputs approaching 1 MIPS per MHz allowing the system designer to optimize power consumption versus processing speed.

FEATURES:
 High Performance, Low Power Atmel®AVR® 8-Bit Microcontroller Family
 Advanced RISC Architecture
-131 Powerful Instructions – Most Single Clock Cycle Execution
-32 x 8 General Purpose Working Registers
-Fully Static Operation
-Up to 20 MIPS Throughput at 20MHz
-On-chip 2-cycle Multiplier
-Write/Erase Cycles: 10,000 Flash/100,000 EEPROM
-Data retention: 20 years at 850C AND 100 years at 250C
-Programming Lock for Software Security
 Operating Voltage: 1.8 - 5.5V
 Temperature Range: -400C to 850C
 Speed Grade: 0 - 4MHz@1.8 - 5.5V, 0 - 10MHz@2.7 - 5.5.V, 0 - 20MHz @ 4.5 - 5.5V
 Power Consumption at 1MHz, 1.8V, 250C
- Active Mode: 0.2mA
-Power-down Mode: 0.1μA
-Power-save Mode: 0.75μA (Including 32kHz RTC)

SERIES ALTERNATIVES:
A common alternative to the ATmega328 is the "picoPower" ATmega328P. A comprehensive list of all other member of the megaAVR series can be found on the Atmel website.

APPLICATIONS:
Today the ATmega328 is commonly used in many projects and autonomous systems where a simple, low-powered, low-cost micro-controller is needed. Perhaps the most common implementation of this chip is on the popular Arduino development platform, namely the Arduino Uno and Arduino Nano models.

Step 3: DTMF BOARD

WITH THE HELP OF THIS DTMF BOARD, THE SIGNALS SENT FROM OUR MOBILE PHONE IN THE FORM OF FREQUENCIES ARE CONVEYED INTO LOGIC VALUES AND ARE FEEDED INTO THE ARDUINO BOARD,

WHAT IS DTMF?
DTMF stands for Dual Tone Multi Frequency.
DTMF is a common communication term for touch tone phones. The tones formed when dialing on the keypad (DTMF digits or DTMF number) on the phone can be used to characterize the digits, and some different tone is used for each digit. DTMF signaling is mainly used in DTMF phones, telephone switching system. A number of companies make microchips that send and receive DTMF signals. The Telephony Application Program Interface (TAPI) provides a way for a program to detect DTMF digits.

HOW DTMF DECODER WORKS?
Yet, there is always a possibility that a random sound will be on the similar frequency which will trip up the DTMF sounds system. It was recommended that if two tones were used to represent a digit, the probability of a false signal happening is ruled out, thus the name ‘Dual Tone’. This is the basis of using dual tone in DTMF communication. DTMF dialing uses a keypad with 12 or 16 buttons. Each key pressed on the keypad generates two tones of particular frequencies, so a voice or a random signal cannot mimic DTMF signaling tones. One tone is generated from a High DTMF frequency group of tones and the other from Low DTMF frequency group.
When a button is pressed, both the row and column tones are generated by the telephone or touch tone instrument. These two tones will be distinctive and different from tones of other keys. So there is a low and high frequency associated with a button, it is essentially the sum of two waves is transmitted. This elementary principle can be extended to a range of applications. Each row and column of the keypad corresponds to a certain tone and creates a specific frequency. Each button lies at the intersection of the two tones.


APPLICATIONS:
DTMF signals can be transmitted over a radio to switch ON or switch OFF home appliances, flash lights, motors, cameras, warning systems, irrigation systems and so on. These encoded data can be stored and processed in a microcontroller to perform different tasks (I.e): Automatic Garage Door Opening System, Cell Phone Controlled Robotic Vehicle using DTMF Technology etc,...

Step 4: MOTOR DRIVER CIRCUIT

THE MOTOR DRIVER ACTS AS A RELAY AND THUS OPERATES THE SERVO MOTOR AS PER THE COMMAND EXECUTED IN THE ARDUINO BOARD,

FEATURES:
.OPERATING SUPPLY VOLTAGE UP TO 46 V
.TOTAL DC CURRENT UP TO 4 A
.LOW SATURATION VOLTAGE
.OVERTEMPERATURE PROTECTION LOGICAL "0" INPUT VOLTAGE UP TO 1.5 V (HIGH NOISE IMMUNITY)


DESCRIPTION:
The L298 is an integrated monolithic circuit in a 15- lead Multiwatt and PowerSO20 packages. It is a high voltage, high current dual full-bridge driver designed to accept standard TTL logic levels and drive inductive loads such as relays, solenoids, DC and stepping motors. Two enable inputs are provided to enable or disable the device independently of the input signals. The emitters of the lower transistors of each bridge are connected together and the corresponding external terminal can be used for the connection of an external sensing resistor. An additional supply input is provided so that the logic works at a lower voltage.

Step 5: WORKING

FINALLY AFTER ALL THE NECESSARY WIRE CONNECTIONS ARE MADE, THE PROJECT IS READY TO WORK IN ACCORDANCE TO THE COMMAND WE GIVE,
By connecting an AUX cable with the phone and the local board, the signals can be transferred to the ARDUINO BOARD and thus the command is executed.
In my project I've feeded only a few commands,
say for example, if I click 1 the car goes forward
2 -> backward
3 -> turns right
4 -> turns left
5 -> stops at the current point

In addition it also has a pair of IR Sensors, which detects the obstacles coming it's way and thus the vehicle turns a 90° in the opposite direction so as to avoid an imminent collision.

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