The document describes the design of an electronics and programming project for a minor project involving an Atmega32 microcontroller, H-bridge circuit, DC motors, and programming in AVR Studio 4 to control the movement and direction of the motors through switches and sensors. Electronic components include an Atmega32 microcontroller, crystal oscillator, resistors, capacitors, diodes, and switches to operate the motors and LEDs according to programmed instructions loaded onto the microcontroller. The goal is to build a differentially-driven programmable robot using a basic H-bridge circuit design to reverse the polarity of the DC motors to control forward and backward movement.

1. Minor project OIST Electronics & Communication Group members: Aamir Hussain Abhikalp Gupta Alind Trivedi Anuj Koshti Bhrigu Raj Sharma

2. Prime Focus- Electronic components and circuitry involved Mechanical aspect Programming part

4. Electronic components Atmega32 microcontroller Crystal oscillator Resistors capacitors Diode Drum switches H-bridge

5. Atmega32 Microcontroller

6. Key features… 8-bit Microcontroller Up to 1 MIPS Throughput at 16MHz On-chip Analog Comparator Operating Voltages - 4.5-5.5V for ATmega32 Speed Grades - 0-16 MHz for ATmega32

7. Utility It is being used to operate the two motors Led’s The required programming is loaded in the flash memory, according to which the movement is controlled

8. Crystal oscillator

9. Utility Operates from 0 to 16 mhz. Provides the operating frequency for operation of microcontroller

10. H-bridge Enables a voltage to be applied across a load in either direction. These circuits are often used in robotics and other applications to allow DC motors to run forwards and backwards.

11. H-bridge utility

12. Circuit of H-bridge

13. The two basic states of an H bridge

14. How H-Bridge works Off Forward Reverse

15. The following table summarizes operation, with S1-S4 corresponding to the diagram above. ACTION OF MOTOR S1 S2 S3 S4 Result 1 0 0 1 Motor moves right 0 1 1 0 Motor moves left 0 1 0 1 Motor brakes 1 0 1 0 Motor brakes

16. Others… Resistors- for control of current flow Capacitors- for uninterrupted voltage FET- for voltage control Switches Diodes

18. Actuators Actuators are mechanical devices which converts energy into motion The energy can be hydraulic, pneumatic or electric. In order to avoid the complexity we have chosen dc motor as actuator.

19. Parameters for selecting a motor Revolution per minute of shaft (rpm) Velocity of wheel Torque Power Voltage Current

20. RPM of Motor rpm of motor is defined as speed of the shaft without any load The rpm depends on the load The rpm is inversely proportional to torque.

21. Velocity It is the rotating speed of the wheel Depends on the rpm & radius of the wheel. V =2*∏*r* ω For a constant wheel radius, rpm can be used to control the velocity.

22. Torque Torque α (1 / rotational speed or rpm) On increasing the torque rpm will decrease & vice versa Having a small load on robot we choose a motor having less torque & more speed

23. Power Motor Power = Torque * rpm Required power = Force * velocity Required power will depends on mass of robot radius of wheel To drive robot efficiently:- Motor power > Required power

24. Voltage DC motors are non polarized i.e. on reversing the polarity the direction of rotation of wheel changes. Torque is directly proportional to applied voltage.

25. Current The operating current is the average current drawn by the motor which is required to drive the robot. To turn the wheel clockwise or anticlockwise, the direction of current is reversed which is done through H-bridge.

26. Selection of motor With all parameters including rpm, velocity, torque, power, current and voltage required to drive the motor efficiently a geared dc motor of following specifications is selected: 100RPM 9V DC with Gearbox 6mm shaft diameter with internal hole 125gm weight 1.2kgcm torque No-load current = 60 mA(Max), Load current = 300 mA(Max)

28. What is Differential drive? The differential drive is a two-wheeled drive system.

29. The drive wheels are usually placed on each side of the robot and toward the front

30. Non driven wheel (metal ball)

31. Pros: Simplicity Effective for plane surfaces Cost Effective Power Efficient

33. Programming …………….. For programming software used: Win AVR AVR studio 4 PL2303 USB driver USB programmer

34. Why AVR studio 4…………? AVR Studio 4 includes a debugger that supports run control source and instruction-level stepping Registers I/O views target configuration and management

35. Standard program This program is made on AVR STUDIO 4 in the high level language (user friendly language) which includes libraries for the compiling and designing of program. #include <avr/io.h> int main() { Step 1 Set pin2 (PD0) and pin3 (PD1) as output pin; Step 2 Set pin15 (PB1) as output pin; Step 3 Send 0 at PD0 and 1 at PD1; Step 4 Send 1 at PB1; While(1) { //do any job here } Return 0; }

36. Sample program This program is for the forward movement of this programmable moving robot. #include<avr/io.h> #include<util/delay.h> #include<compat/deprecated.h> int main() { DDRC=0b11111111;//data direction register c is initialised by binary value while(1) { sbi(PORTC,1); //sets a bit of portc of ATMEGA32 sbi(PORTC,2); //sets a bit of portc of ATMEGA32 } return(0); }

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