17-04-2012, 04:32 PM
LCD
INTRODUCTION
This is the first interfacing example for the Parallel Port. We will start with something simple. This example doesn't use the Bi-directional feature found on newer ports, thus it should work with most, if no all Parallel Ports. It however doesn't show the use of the Status Port as an input. So what are we interfacing? A 16 Character x 2 Line LCD Module to the Parallel Port. These LCD Modules are very common these days, and are quite simple to work with, as all the logic required to run them is on board.
CIRCUIT DESCRIPTION
Above is the quite simple schematic. The LCD panel's Enable and Register Select is connected to the Control Port. The Control Port is an open collector / open drain output. While most Parallel Ports have internal pull-up resistors, there are a few which don't. Therefore by incorporating the two 10K external pull up resistors, the circuit is more portable for a wider range of computers, some of which may have no internal pull up resistors.
We make no effort to place the Data bus into reverse direction. Therefore we hard wire the R/W line of the LCD panel, into write mode. This will cause no bus conflicts on the data lines. As a result we cannot read back the LCD's internal Busy Flag which tells us if the LCD has accepted and finished processing the last instruction. This problem is overcome by inserting known delays into our program.
VOLTAGE SENSING
A Voltage sensing is a device that detects electrical Voltage across two terminal of a wire, and generates a signal proportional to it.
We are using Potential Transformer to sense the voltage across the Induction Motor of our proposed system.
APPLICATIONS
The various applications of the proposed system are given as following
• The proposed system is of low cost
• It can be used in household appliances as well as in Industrial purpose due to monitoring by PC
• User friendly
• More efficiency of controlling
• Convenience to operate
CONCLUSION
This paper deals with the design and analysis of PWM fed speed control of induction motor using PC. An analysis of control of the speed of induction motor is established by a equivalent model circuit. The project has been successfully completed with the main aim of controlling the speed of Induction motor with PWM technique using PIC microcontroller.
The project has been designed using visual basic, MPLAB for PIC microcontroller and LCD with the added advantages of flexibility and ease in working. The implementation of project is also very easy and understandable. This is a user friendly project in which proper care has been taken to keep the circuit arrangement as required by the user.