Interfacing of Graphic LCD Module to AT89S52

The most character LCD module can be interface with micro-controller in any of these two ways of interface:
1. 4-Bit Interface ( a little bit slow LCD interface but we can safe the data input/output lines of micro-controller for other use, i.e. to interface other hardware’s to it.)2. 8-Bit Interface ( This is speedy LCD interface method to any microprocessor or microcontroller, more using this interface method, one can easy develop a program in c++/C or VB6 to directly interface a character LCD with PC parallel port, some it requires in certain application.)
Graphic LCD Module:

But The Graphic LCD Module requires 8-bit data bus (DB0 – DB7). The Graphic LCD Module is normally ( foreample JHD12864J ) splited logically into two portions. One half with controller #1 (CS1) driving the left half of the display, and controller #2 (CS2) driving the right half. These two portions map directly to the physical display areas of graphic LCD. With a correct controlling sequence on pin CSx (x=1,2), D/I, and R/W, we can write any pattern, image, animation , and text in bigger fonts directly to the LCD screen at a designated column position.

The Interface of a Graphic LCD with micro-controller 8051 family.

Here we will discuss, the interfacing of GLCD (Graphic LCD module ) with micro-controller 8051 family only, I have used At89s52 in this project but you can use any micro-controller of 8051 family like at89c51 or at89c2051 , it will work with all (hopefully but not granty). There are two ways to interface the LCD with AT89S52:

1. Address/data bus memory map, i.e. use the LCD as a piece of external RAM

2. Direct I/O connection by writing high/low signal to LCD.

The first of all, we start with a task to understand the control sequence required to read or write data to the LCD module. There are several points, instruction, steps and sequences to show a graphic data or image on graphic LCD. Most common and important of them are described here as follows:

1. RS controls data or command action (D/I=LOW ? command; D/I=HIGH ? data).

2. Horizontal pixel addressed by Y address counter (0-63). The Y address indicates the column position in the horizontal direction. As, earlier describes the LCD is splitted logically in half with controller #1 (CS1) driving the left half of the display, and controller #2 (CS2) driving the right half. So the range of Y address counter is from 0 to 63, (128/2 = 64).

3. The term Page refers to 8-pixel vertically. There are 8 pages ranging from 0 to 7, thus matching a vertical matrix size of 64 pixels.

4. R/W controls data READ / WRITE (R/W=LOW ,, write; R/W=HIGH ,, read).

5. CS1, CS2, E, and RST pins are also control PINs of Graphic LCD. Direct low-level access and signal timing requirement will be taken care by hardware dependent functions.

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About author

This article was written by admin

Admin has over twenty years experience in the electronics industry, largely dedicated to embedded software. A frequent presenter at conferences and seminars and author of numerous technical articles. Working presently as Development Manager in India. A firm Believer in Knowledge grows when it shared.


Comments (5)
  1. Teofila Dagnan says - Posted: October 25, 2012

    There is evidently a bundle to know about this. I suppose you made some good points in features also.

  2. Mohit Indani says - Posted: May 22, 2013

    i want to connect 160 x 32 graphic lcd with ARM…in that graphic lcd there is ST7920 lcd controller ic…

  3. Siddharth says - Posted: June 16, 2013

    Is there a post that has to come in future to fill up this one? Cause I can’t see the rest of it..

    • admin says - Posted: June 19, 2013

      Yes there are three parts of this tutorial ….i am little busy …hope by next week i will release them…thanks!

  4. jalaja says - Posted: July 2, 2013

    This tutorial is good still i need more information on this………………..please provide me more

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