05-04-2011, 10:06 AM
SUBMITTED BY:
ManoJ Sehgal
[attachment=11715]
Mobile Controlled ROBOT Using DTMF Technology
Introduction
What is a Mobile controlled DTMF ROBOT?
DTMF Mobile ROBO is a machine that can be controlled with a mobile . In this project, the robot is controlled by a mobile phone that makes a call to the mobile phone attached to the robot. 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. This tone is called "Dual Tone Multiple-Frequency" (DTMF) tone. The robot perceives this DTMF tone with the help of the phone stacked on the robot. The received tone is processed by the microcontroller with the help of DTMF decoder. The microcontroller then transmits the signal to the motor driver ICs to operate the motors & our robot starts moving
Why build a DTMF ROBOT?
Conventionally, Wireless-controlled robots use rf circuits, which have the drawbacks of limited working range, limited frequency range and the limited control. Use of a mobile phone for robotic control can overcome these limitations. It provides the advantage of robust control, working range as large as the coverage area of the service provider, no interference with other controllers and up to twelve controlles.
Although the appearance and the capabilities of robots vary vastly, all robots share the feature of a mechanical, movable structure under some form of control. The Control of robot involves three distinct phases: perception, processing and action. Generally, the preceptors are sensors mounted on the robot , processing is done by the on-board microcontroller or processor, and the task is perfomed using motors or with some other actuators.
POJECT OVERVIEW:
In this project the robot, is controlled by a mobile phone that makes call to the mobile phone attached to the robot in the course of the call, if any button is pressed control corresponding to the button pressed is heard at the other end of the call. This tone is called dual tone multi frequency tome (DTMF) robot receives this DTMF tone with the help of phone stacked in the robot
The received tone is processed by the atmega16 microcontroller with the help of DTMF decoder MT8870 the decoder decodes the DTMF tone in to its equivalent binary digit and this binary number is send to the microcontroller, the microcontroller is preprogrammed to take a decision for any give input and outputs its decision to motor drivers in order to drive the motors for forward or backward motion or a turn.
The mobile that makes a call to the mobile phone stacked in the robot acts as a remote. So this simple robotic project does not require the construction ofreceiver and transmitter units.
DTMF signaling is used for telephone signaling over the line in the voice frequency band to the call switching center. The version of DTMF used for telephone dialing is known as touch tone .
DTMF assigns a specific frequency (consisting of two separate tones) to each key s that it can easily be identified by the electronic circuit. The signal generated by the DTMF encoder is the direct al-gebric submission, 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 1336hz and 770hz to the other end of the mobile. The tones and assignments in a dtmf system shown below
Figures shows the block diagram and cicuit diagram of the microcontroller- based robot. The important components of this robot are DTMF decoder, Microcontroller and motor driver.
An MT8870 series dtmf decoder is used here. All types of the mt8870 series use digital counting techniques to detect and decodeall the sixteen DTMF tone pairs in to a four bit code output. The built -in dila tone regection circuit eliminated the need for pre- filtering. When the input signal given at pin2 (IN-) single ended input configuration is recognized to be effective, the correct four bit decode signal of the DTMF tone is transferred to Q1 (pin11) through Q4(pin14) outputs.
The atmega 16 is a low power, 8 bit, cmos microcontroller based on the AVR enhanced RISC architecture. It provides the following feature: 16kb of in system programmable flash memory with read write capabilities, 512bytes of EEPROM, 1KB SRAM, 32 general purpose input/output lines. 32 general purpose working registers. All the 32 registers are directly connected to the arithmetic logic unit, allowing two independent registers to be accessed in one signal instruction executed in one clock cycle. The resulting architecture is more code efficient. Outputs from port pins PD0 through PD3 and PD7 of the microcontroller are fed to inputs IN1 through IN4 and enable pins (EN1 and EN2) of motor driver L293d respectively, to drive geared motors. Switch S1 is used for manual reset.
the notations are :
ic1 - mt8870
ic2 - atmega16
ic3 - l293d
ic4 - cd7004
r1,r2 - 100k resistances
r3 - 330k resistances
r4-r8 - 10k resistances
c1- 0.47 micro farat capacitor
c2,c3,c5,c6 - 22pfarat capacitor
c4 - 0.1micro farat capacitor
xtal1 - 3.57 mhz crytal
xtal2 - 12mhz crystal
s1 - push to on switch
m1,m2 - 6v 50rpm motor
batt- 6v
DTMF Tone
The DTMF technique outputs distinct representation of 16 common alphanumeric characters (0-9, A-D, *, #) on the telephone. The lowest frequency used is 697Hz and the highest frequency used is 1633Hz, as shown in Table 1.
The DTMF keypad is arranged such that each row will have its own unique tone
frequency and also each column will have its own unique tone frequency. Above is a
representation of the typical DTMF keypad and the associated row/column
frequencies. By pressing a key, for example 5, will generate a dual tone consisting of
770 Hz for the low group and 1336 Hz for the high group.
DTMF Decoder
The MT-8870 is a DTMF Receiver that integrates both band split filter and decoder functions into a single 18-pin DIP or SOIC package. It is manufactured using CMOS process technology. The MT-8870 offers low power consumption (35 mW max) and precise data handling.
Its filter section uses switched capacitor technology for both the high and low
group filters and for dial tone rejection. Its decoder uses digital counting techniques
to detect and decode all 16 DTMF tone pairs into a 4-bit code. External component
count is minimized by provision of an on-chip differential input amplifier, clock
generator, and latched tri-state interface bus. Minimal external components required
includes a low-cost 3.579545 MHz color burst crystal, a timing resistor, and a timing
capacitor.
The filter section is used for separation of the low-group and high group tones and
it is achieved by applying the DTMF signal to the inputs of two sixth order switched
capacitor band pass filters, the bandwidths of which corresponds to the low and high
group frequencies. The filter section also incorporates notches at 350 and 440 Hz for
exceptional dial tone rejection. Each filter output is followed by a single order
switched capacitor filter section which smoothes the signals prior to limiting. Limiting
is performed by high-gain comparators which are provided with hysteresis to prevent
detection of unwanted low-level signals. The outputs of the comparators provide full
rail logic swings at the frequencies of the incoming DTMF signals.
Following the filter section is a decoder employing digital counting techniques to
determine the frequencies of the incoming tones and to verify that they correspond tothe standard DTMF frequencies.
ABOUT MICROCONTROLLER UNIT:
VARIOUS TYPE OF MICROCONTOLLERS:
First microcontroller is ‘8031’
FEATURES:
It is Intel’s product. Neither a microprocessor nor a microcontroller.
It is a 8-bit controller.
Internally no ROM is provided i.e. code is outside the chip.
FEATURES:
It is a first complete 8-bit microcontroller.
It is a name of a family. In which the instruction set, pin configuration, architecture are same, only memory storage capacity is different.
Internally PROM (programmable read only memory) is provided so it called one time programmable (OTP).
Third microcontroller is ‘AT89C51’
FEATURES:
It is ATMEL’s product.
It is a similar to 8051 microcontroller i.e. having same instruction set, pin configuration, architecture.
It is a also 8-bit microcontroller. It’s cost is only Rs10 more than 8051.
It uses EPROM (erasable programmable read only memory) or FLASH memory.
It is Multiple time programmable (MTP) i.e. 1000 times. So it is better than 8051.
In ‘AT89C51’, ‘C’ stands for CMOS technology used in the manufacturing of the I.C.
ATMEL89C52
Description:
The AT89C52 is a low-power, high-performance CMOS 8-bit microcomputer with 8K bytes of Flash programmable and erasable read only memory (PEROM). The deviceis manufactured using Atmel’s high-density nonvolatile memory technology and is compatible with the industry-standard 80C51 and 80C52 instruction set and pinout.
The on-chip Flash allows the program memory to be reprogrammed in-system or by a
conventional nonvolatile memory programmer. By combining a versatile 8-bit CPU
with Flash on a monolithic chip, the Atmel AT89C52 is a powerful microcomputer
which provides a highly-flexible and cost-effective solution to many embedded control applications.
