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

Explain three dimensional transformations, Explain Three Dimensional Transf...

Explain Three Dimensional Transformations A 3D geometric transformation is utilized extensively in object modelling and rendering. 2D transformations are naturally extended to

What is the minimum number of control points, Question: A curve shape ha...

Question: A curve shape has three quadratic Bézier curve segments. The curves have been joined sequentially so that continuity of the first derivative of the resulting curve sha

Characteristics of digital video, Digital video can be characterized by a f...

Digital video can be characterized by a few variables: Frame rate : various frames displayed per second. The illusion of motion may be experienced on frame rates as low as 12 f

Objectives-introduction to computer graphics, Objectives After complet...

Objectives After completing this section, you must be familiar with: explain computer graphics, its characteristics and features; Conversations about applicat

Hypertext/media and human memory, Hypertext/media and Human Memory Huma...

Hypertext/media and Human Memory Humans associate pieces of information along with other information and make complicated knowledge structures. Thus, this is also said as the h

Computational algorithm for simulating physical system, computational algor...

computational algorithm for simulating the behavior of different physical and mathematical systems Monte Carlo methods are an extensively utilized class of computational algor

Point clipping - 2-d viewing and clipping, Point clipping - 2-d viewing and...

Point clipping - 2-d viewing and clipping Point clipping is the method related to suitable display of points in the scene, though this type of clipping is utilized less freque

What is the purpose of saving selections, Question 1: (a) Once a select...

Question 1: (a) Once a selection is made, what area of the image can be edited? (b) What is the purpose of saving selections? (c) How can you move a selection while you a

Explain the term- control, Explain the term- Control Traffic lights (co...

Explain the term- Control Traffic lights (controlling the sequence of lights to maintain optimum traffic flow), chemical and nuclear plants (opening and closing valves, safety

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