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

Aspect ratio - display devices, Aspect ratio - Display Devices Ratio of...

Aspect ratio - Display Devices Ratio of vertical points to horizontal points necessary to produce equal length lines in both directions on the screen. For example, in a CRT mon

Image space -approaches for visible surface determination, Image Space Appr...

Image Space Approach -Approaches for visible surface determination The initial approach as image-space, determines that of n objects in the scene is visible at every pixel in

List of 3-d animation software, List of 3-D Animation Software Here is ...

List of 3-D Animation Software Here is a short list of several 3-D animation software are - Softimage ( Microsoft) -  Alias/Wavefront ( SGI) -  3D studia MAX (Autodesk

Principal vanishing point write respect to z-axis, Principal vanishing poin...

Principal vanishing point write respect to Z-axis Principal vanishing point w.r.t z-axis: By the 3rd row of matrix equation, we declare that the principal vanishing point w

Distinguish between window port and view port, Distinguish between window p...

Distinguish between window port & view port?  A portion of a picture that is to be displayed by a window is called as window port. The display area of the part selected or the f

Explain about the computer animation, Explain about the Computer animation ...

Explain about the Computer animation Computer animation is the art of creating moving images by computer software and hardware. For 3D animation, objects are designed on a

Printing press discovered in 16th century, Printing Press discovered in 16t...

Printing Press discovered in 16th century: Books provided more role models & multiple perspectives. Exposure to books demanded that learners employ critical thinking to r

Two modes of operation of tablets - cad and cam, Two Modes of Operation of ...

Two Modes of Operation of Tablets Tablets typically sustain two modes of operation as: 1)  Digitizer Mode: creates a one-for-one connection between screen and tablet.

Explain any ten types of artistic filters, Question 1 Explain any ten type...

Question 1 Explain any ten types of artistic filters Question 2 What is Freehand Tool? Explain the procedure of drawing lines and curves with freehand tool Question 3 Ho

Adobe premiere - softwares for computer animation, Adobe Premiere - Softwar...

Adobe Premiere - Softwares for computer animation It just like the name as is generated by Adobe. This is a tool used to composite digitized video, stills and applies a variet

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