Time delay and busy flag method, Computer Graphics

Assignment Help:

1. Using a time Delay Method

The delay required between issuing each character to the LCD is about 5-10ms (it's simply known as DELAY). When programming an LCD, a long delay is also needed for the power-up process, (it's called long delay LDELAY). For the LCD input to be enabled, the short delay is required to make the En signal wide enough.
The data is sent in nibbles in 4-bit mode. The higher nibble is sent first, and then the lower nibble. In order to enable the 4-bit mode of LCD, the follow special sequence of initialization below was used. This is also known as special reset sequence of LCD. The special reset sequence is as follows:

  1. Wait for about 20mS
  2. Then send the first init value (0x20 - for 4-bit and 0x30 for 8-bit)
  3. Wait for about 10mS
  4. Send second init value (0x20)
  5. Wait for 1mS
  6. Send third init value (0x20)
  7. Wait for 1mS
  8. Select bus width (0x20)
  9. Wait for 1mS

The busy flag will only be active after the above reset sequence is completed. The busy flag is not normally used in 4-bit mode; instead I had used a certain amount of delay usually within the range from 300 to 600us or can also write some code for reading two nibbles from the LCD. This delay might vary depending on the LCD used and crystal frequency on which LCD controller is running, but 400us usually works perfectly.

2. Using Busy Flag Method

The Data line D7 is the busy flag, and can be read when R/W=1 and RS=0. When D7 is high i.e. (busy flag =1), the LCD is busy dealing with the internal operations and will not acknowledge any new information. When D7=0, the LCD is ready to receive new information.


Related Discussions:- Time delay and busy flag method

Random scan display device - types of refresh monitors, Random Scan Display...

Random Scan Display Device The original cathode ray tube, developed in the late fifties and early sixties, produced charts and pictures, line through line on the tube surface

What is a model sheet?, Question 1 Briefly explain the twelve principles o...

Question 1 Briefly explain the twelve principles of animation Question 2 Explain the methods to set-up pre and post-infinity curves Question 3 What is a model sheet? Exp

What is meant by addressability, What is meant by Addressability? Ans. ...

What is meant by Addressability? Ans. Addressability is the number of individual dots per inch (d.p.i.) that can be formed. If the address of the current dot is (x, y) then the

Introduction of curves and surfaces, Introduction of Curves and Surfaces ...

Introduction of Curves and Surfaces This section has covered the methods of generating polygons, closed and curves surfaces. Under those methods we have discussed different ty

PERT , Program of PERT in c language

Program of PERT in c language

Buffer areas required for z-buffer algorithm, Buffer Areas Required For Z-B...

Buffer Areas Required For Z-Buffer Algorithm For applying z-buffer algorithm, we need two buffer areas or two 2-Dimentional arrays: 1) Depth-buffer [i,j], to sa

Overstriking, why overstriking is harmful.justify

why overstriking is harmful.justify

Types of graphic images, Types of Graphic Images: Graphic images have...

Types of Graphic Images: Graphic images have been processed through a computer can generally be divided in two distinct categories. That image is either bitmap files or vecto

General perspective transformation, General Perspective transformation w.r....

General Perspective transformation w.r.t. an arbitrary center of projection Suppose here that the COP is at C(a,b,c), as demonstrated in Figure. By Figure, the vectors CP

Understanding the concept of hypertext and hypermedia, Understanding the Co...

Understanding the Concept of hypertext and hypermedia: For know the principle of Hypertext and Hypermedia we will look at how the human memory works.

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd