PROJECT PRESENTATION ON CELLPHONE OPERATED ROBOTIC ASSISTANT ELECTRONICS ENGINEERING DEPARTMENT SVNIT, SURAT-395007, INDIA
Prepared by: Anurag Gupta (U05EC401) Dhrumeel Bakshi (U05EC326) Dileep Dhakal (U05EC388) Jaidatt Sharma (U05EC338) Kankan Ghosh (U05EC340) Guided by: Mr. Abhilash Mandloi (Guide) Mr. N.B. Kanirkar (Co-Guide)
1. INTRODUCTION
OVERVIEW AND DESIGN STEPS Aim of the project is to use a mobile phone to control a robotic arm mounted on a land rover. Provides robust control, large working range and upto 12 controls. Control of robot involves 3 different phases:1. Perception 2. Processing 3. Action
1. PRECEPTION First part is the decoding of DTMF tone generated by pressing a key in calling phone. Audio signal output from receiving phone is fed to DTMF decoder chip. Decoder chip converts DTMF tone into binary codes to be fed to microcontroller. CM8870 IC used as DTMF decoder in our project
2. PROCESSING After preception stage, microcontroller processes the binary codes it receives. Microcontroller is pre-programmed in C to perform specific task according to input bits. Atmel s ATmega16 is used for processing. Program is written using AVR Studio and uploaded using SuperPro.
3. ACTION Final stage is rotation of motors based on input given by the microcontroller. Two DC motors of 30 rpm are used for the land rover and three servo motors of Futaba S3003 are used for robotic arm DC motors are driven by motor driver IC L293D. Servo motors are driven by PWM generated by the microcontroller.
BASIC BLOCK DIAGRAM OF PROJECT
2. DTMF SIGNALS AND DTMF DECODING CIRCUIT
DTMF Dual Tone Multiple-Frequency. Signals generated by the superposition of two pure sinusoidal tones. Commonly used for telephone signalling over the line in the voice-frequency band, to the call switching center. Developed as a very reliable alternative to pulsedialing.
DTMF represents numbers/digits as voice signals.
The 12-keys numeric pad. 0 to 9 keys * and # keys DTMF assigns a unique sound to each key Keys are arranged in a matrix of 3 columns and 4 rows.
Grouping of Frequencies The DTMF signal generated is the sum of two sinusoidal tones.
Tone frequencies, are defined by the Precise Tone Plan. Harmonics and intermodulation products will not cause an unreliable signal No frequency is a multiple of another. No frequency is the sum or difference of 2 other frequencies.
Communication Overview
CM8870 CM8870 is a very commonly used chip for DTMF decoding. It is a state of the art single chip DTMF receiver incorporating switched capacitor filter technology and an advanced digital counting/averaging algorithm for period measurement.
CM8870 Truth Table
Limitation on number of function codes 12 DTMF tones are available to us (using a common touch-tone phone). Number of functions may be extended to 144 by programming the microcontroller to accept two codes instead of one. Two key presses will be required from the control mobile phone.
Advantages of using the DTMF communication scheme Working range is as large as the coverage area. Problems due to Harmonics and their interference are eliminated. Only one tone per group is allowed. This eliminates reception of erroneous codes. DTMF tones if received from external sources, are neglected by amplitude comparison of the two tones. Simple usage, and short numeric codes for control.
DECODER CIRCUIT USED IN PROJECT
3. ATMEGA16 MICROCONTROLLER
ATMEGA16 FEATURES & ARCHITECTURE Advanced-RISC architecture. 16K bytes of In-System Programmable Flash Program memory. Three timers/counters with compare modes. Internal and external interrupts. 4 PWM channels. 8 channnel 10-bit ADC. 32 general-purpose registers. High-performance, Low-power AVR 8-bit Microcontroller.
Q. WHY USE ATMEL S ATMEGA16? Widely used. Easily available. Cost effective. Speed of execution of instructions. Flexible instruction set. Vast documentation. Easily available support and development tools.
PROGRAMMING & DEVELOPMENT TOOLS Very popular compilers and uploaders available. Easy compliancy with C, BASIC, PASCAL, C++, FORTRAN,etc WinAVR, AVR Studio, AVRTools, AVRDude, AVR Dragon, SuperPro (by Xeltek) etc. Development kits are cheap and easily available.
INTERFACING CIRCUIT USED IN PROJECT
4. SERVO AND DC MOTOR CONTROL
SERVO MOTOR CONTROL USING PWM SIGNALS A servo consists of a dc motor, gear train, potentiometer, and some control circuitry all mounted compactly in a case. Shaft rotation at relatively slow speeds. Easily controlled by a microcontroller. 3 wires: white, red, and black
White - control signal, red - power (usually 4.8 V to 6 V), black - ground. The control circuitry inside the servo must receive a stream of pulses whose widths may vary between about 1 and 2 ms. A potentiometer coupled to the rotation of the output shaft produces a voltage corresponding to the angle of the shaft. The control circuitry compares the average voltage of the control signal with the voltage from the potentiometer, and the shaft rotates until the two voltages are the same.
DIFFERENT PWM INPUTS
SERVO MECHANISM - BLOCK DIAGRAM
GENERATION OF PWM SIGNALS USING ATMEGA16 Timers Timer/Counter 0 8 bit Timer/Counter 1 16 bit Timer/Counter 2 8 bit Pulse generation and variation
TIMER REGISTERS TCNTn : Timer/counter register OCRn: Output Compare Register TIFR : Timer Interrupt Flag register TIMSK : Timer Interrupt Mask register ICR1 : Input Capture register
MODES OF OPERATION Normal Mode: Simplest mode. Count sequence always up. Clear Timer on Compare Match (CTC) Mode
Phase Correct PWM Mode Dual slope operation. Output compare set in one direction, cleared in other.
Fast PWM Mode Single slope operation Easy to code. Maximum frequency twice as high as Phase correct PWM mode.
CONTROL WORD FORMATS AND REGISTER VALUES FOR FAST PWM MODE Timer/Counter 0 Control Register Bit 7 FOC0: Force Output Compare Bit 6, 3 WGM01:0: Waveform Generation Mode Bit 5:4 COM01:0: Compare Match Output Mode Bit 2:0 CS02:0: Clock Select
TIMER 1 FOR PWM Advantages: o Higher resolution o 2 PWM channels OC1A, OC1B o TOP value can be set using ICR1
Timer/Counter1 Control Register A TCCR1A Timer/Counter1 Control Register B TCCR1B
DC MOTOR CONTROLLER: L293D Microcontroller output is not sufficient to drive DC motors so L293D is used. L293D comes in 16-pin DIP. It can provide currents upto 600mA at voltages from 4.5V to 36V. It can be used to drive inductive loads such as relays, solenoids etc and bipolar stepper motors. In the project it is used for simultaneous bi-directional control of two DC motors.
DC MOTOR CONTROL
L293D CIRCUIT USED IN PROJECT
5. FINAL CIRCUIT SCHEMATIC, CODE AND EXPERIMENTAL RESULTS
SOFTWARES USED FOR PROGRAMMING AND SIMULATIONS AVR Studio for programming the Atmega16 microcontroller and generating the HEX files. SuperPro USB Series for burning the internal flash memory of ATmega 16 using SuperPro 280U hardware. Proteus ISIS for designing and simulating the circuit. Circuit layout generation using Proteus Ares.
AVR STUDIO FOR ATMEGA 16 PROGRAMMING Program can be written in both C and assembly language. Flags, Timers, Ports and Register bank can be observed directly. Hex files can be generated. Easy debugging and troubleshooting.
WRITING CODE ON AVR STUDIO
SUPERPRO USB SERIES Freely available software to write the HEX file to the microcontroller. Uses SUPERPRO Model 280U as the burner. Device support large number of Microcontrollers, EEPROMs, microprocessors, PROMs. Microcontrollers can be tested and data can be verified. Data can be erased in seconds. USB supported.
UPLOADING PROGRAM USING SUPERPRO
CIRCUIT SIMULATION Cost and time saving. Signal generation and observation Circuit Optimization for the best performance. Program codes can be tested in the virtual microcontroller. Simulation result is an ideal performance parameters. Fault detection and correction. Hex files generated by AVR can be virtually tested in the Proteus ISIS simulator.
FINAL CIRCUIT SCHEMATIC
PROTEUS-ISIS FEATURES Supports large number of Microcontroller Units (MCUs) including ATmega 16. Generating the proper signals for motor controller. Huge gallery of circuit components. Electromechanical components like Servo and DC motors can be simulated. Circuit can be transformed to design a Layout in Proteus Ares software. Hex file can be loaded directly to the MCU and observe the result. Logic analyzer facility.
CIRCUIT SIMULATION ON ISIS
CIRCUIT SIMULATION ON ISIS (CONTD.)
PROTEUS ARES FOR PCB LAYOUT DESIGN Auto routing and placing facility of optimization of the circuit. Custom design facility for implementation of any type of IC (both QFP or DIP package). Circuit designed in Proteus ISIS can be directly transformed to PCB layout design. 3D visualization facility for multi-axis design optimization.
LAYOUT ON PROTEUS ARES
Thank you!