03-08-2012, 02:49 PM
Seminar on DC Motor Full Report
DC Motor.docx (Size: 135.81 KB / Downloads: 38)
Whenever a robotics hobbyist talk about making a robot, the first thing comes to his mind is making the robot move on the ground. And there are always two options in front of the designer whether to use a DC motor or a stepper motor. When it comes to speed, weight, size, cost... DC motors are always preferred over stepper motors. There are many things which you can do with your DC motor when interfaced with a microcontroller. For example you can control the speed of motor; you can control the direction of rotation. In this part of tutorial we will learn to interface and control of a DC motor with a microcontroller. Usually H‐bridge is preferred way of interfacing a DC motor. These days many IC manufacturers have H‐bridge motor driver available in the market like L293D is most used H-Bridge driver IC. H‐bridge can also be made with the help of transistors and MOSFETs etc. rather of being cheap, they only increase the size of the design board, which is sometimes not required so using a small 16 pin IC is preferred for this purpose.
IC L293D Dual H‐Bridge Motor Driver
L293D is a dual H‐Bridge motor driver, so with one IC we can interface two DC motors which can be controlled in both clockwise and counter clockwise direction and if you have motor with fix direction of motion. You can make use of all the four I/Os to connect up to four DC motors. L293D has output current of 600mA and peak output current of 1.2A per channel. Moreover for
protection of circuit from back EMF output diodes are included within the IC. The output supply (VCC2) has a wide range from 4.5V to 36V, which has made L293D a best choice for DC motor driver. nwww.VisionRobo.com
As you can see in the circuit, three pins are needed for interfacing a DC motor (A, B, Enable). If
you want the o/p to be enabled completely then you can connect Enable to VCC and only 2 pins needed from controller to make the motor work. As per the truth mentioned in the image above its fairly simple to program the microcontroller. It also clear from the truth table of BJT circuit and L293D the programming will be same for both of them, just keeping in mind the allowed combinations of A and B.
LM555 Timer
General Description
The LM555 is a highly stable device for generating accurate time delays or oscillation. Additional terminals are provided for triggering or resetting if desired. In the time delay mode of
operation, the time is precisely controlled by one external resistor and capacitor. For astable operation as an oscillator, the free running frequency and duty cycle are accurately controlled with two external resistors and one capacitor. The circuit may be triggered and reset on falling waveforms, and the output circuit can source or sink up to 200mA or drive.
Voltage regulator(7805ic)
7805 is a voltage regulator integrated circuit. It is a member of 78xx series of fixed linear voltage regulator ICs. The voltage source in a circuit may have fluctuations and would not give the fixed voltage output. The voltage regulator IC maintains the output voltage at a constant value. The xx in 78xx indicates the fixed output voltage it is designed to provide. 7805 provides +5V regulated power supply. Capacitors of suitable values can be connected at input and output pins depending upon the respective voltage levels.