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

Overview of hardware primitives, Overview of Hardware Primitives With t...

Overview of Hardware Primitives With the advancement of computer technology, computer graphics has become a practical tool used in real life applications in diverse areas such

Program to implement procedures or functions, The goal of this assignment i...

The goal of this assignment is to implement procedures/functions using x86 assembly. In addition to implementing procedures/functions, this assignment requires to pass arguments us

Distinguish between convex and concave polygons, Distinguish between convex...

Distinguish between convex and concave polygons? If the line joining any two points in the polygon lies totally inside the polygon then, they are called as convex polygons. If

Differentiate between z-buffer method and scan-line method, Differentiate b...

Differentiate between z-buffer method and scan-line method. What is the visibility test made in these methods? Solution : In depth buffer algorithm every pixel location on the

List out the various text clipping, List out the various Text clipping?  ...

List out the various Text clipping?  All-or-none string clipping -if all of the string is inside a clip window, keep it or else discards. All-or-none character clipping - disca

Perform a x-direction shear transformation, 1. If you perform a x-direction...

1. If you perform a x-direction shear transformation and then a y-direction shear transformation, will the result be the same as the one which is obtained when it is simultaneous s

What is transformation, What is Transformation?  Transformation is the ...

What is Transformation?  Transformation is the method of introducing changes in the shape size and orientation of the object using scaling rotation reflection shearing & transl

Bresenham line generation algorithm, Bresenham Line Generation Algorithm ...

Bresenham Line Generation Algorithm This algorithm is exact and efficient raster line generation algorithm. Such algorithm scan converts lines utilizing only incremental integ

Polygon surfaces - curves and surfaces, Polygon Surfaces - Curves and Surfa...

Polygon Surfaces - Curves and Surfaces   By Figure 1 and Figure 2 it is clear that it is possible to store description of objects as a set of surface polygons and similar i

Key frames -traditional animation techniques, Key Frames -Traditional Anima...

Key Frames -Traditional Animation Techniques The senior artists go and draw the main frames of the animation, after a storyboard has been laid out. These main frames are frame

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