Interfacing Graphical LCD with AVR MCU – Part III

Hello Friends,

Welcome Back. This is the continuation of our tutorial series on Graphical LCD Programming. Till now we have made the hardware for testing and setup avr studio project for graphical development. Now as our hardware and software is ready, its time to get our hands dirty by digging deep into ProGFX graphical programming.


The graphical LCD is made up of a grid of pixels. Common resolution is 128×64. That means that their are 64 horizontal lines and each line has 128 pixels. These displays are monochrome that means each pixel can either be ON or OFF. ON pixels looks dark while OFF pixels are nearly invisible. The glcd has a graphic RAM where each bit in ram corresponds to one pixel on screen. You write to the graphic RAM to modify its contents and the screen will change accordingly. The LCD module offers just that much functionality. You can’t do much with that.

graphical lcd matrix

Pixel Matrix of Graphical LCD

You need a graphic library that takes high level commands like

  • Graphic primitives like line,circles, rectangle etc
  • Text Drawing
  • Image/Icon drawing.
  • Double buffering.

and changes the graphic memory accordingly. These operation requires some advance algorithms (at least from beginners point of view!). So the graphic library will help you generate complex graphical output very easily.

Pixel Addressing

The horizontal location is called the X address and its starts from the left hand side(where its value is 0) and increases as we move right. The vertical location is called Y address of pixel its starts from the top (where its value is 0) and increases as we move down. Only positive values are allowed. Pixel is always addressed by specifying its X and Y co-ordinate. It is written in form (x,y). The image below shows address of some pixels.

pixel addressing in 128x64 glcd

Pixel Addressing in 128×64 glcd


In ProGFX engine only two colors are defined they are


Most of the ProGFX functions takes pixel address and color as arguments.

Drawing A Pixel in GLCD

The function which draws a single pixel in ProGFX is called

void GFXRawPutPixel(UINT8 x,UINT8 y,UINT8 color);

The function is very simple. The first argument is the x location of pixel, the second is the y location of pixel, the third is the color of the pixel.


To plot a pixel at (32,24) with black colour.

#include <gfx.h>

void main()
   //Initialize ProGFX Engine

   //Draw a pixel at 32,24 in Black

   //Update the display


Drawing A line in GLCD

A line is a geometrical figure defined by two points. A line can be drawn on GLCD by specifying a start point and an end point. The function in ProGFX which draws a line is explained below.

void GFXLine(UINT8 x1,UINT8 y1,UINT8 x2,UINT8 y2,UINT8 color);


  • x1 = start x co-ordinate.
  • y1 = start y co-ordinate.
  • x2 = end x co-ordinate.
  • y2 = end y co-ordinate.
  • colour = either GFX_COLOR_BLACK or GFX_COLOR_WHITE

Return Value

  • NONE


Draw a line between (16,16) to (100,41) in Black colour

#include <gfx.h>

void main()
   //Initialize ProGFX Engine

   //Draw a line between (16,16) to (100,41) in Black colour

   //Update the display


line in glcd

Line in GLCD

If the line you want to draw is perfectly horizontal or vertical then you may use the following two functions.

  • void GFXHLine(UINT8 x1,UINT8 y1,UINT8 len,UINT8 color);
  • void GFXVLine(UINT8 x1,UINT8 y1,UINT8 len,UINT8 color);

These function takes starting point and the length of line. They are much faster than generic GFXLine() function.

Drawing a Rectangle In GLCD

Rectangle can be drawn on the screen by specifying two points and colour.

  • Top-left point
  • Bottom-right point

The function which draws a rectangle is documented below.

void GFXRect(UINT8 x1,UINT8 y1,UINT8 x2, UINT8 y2,UINT8 color);


  • x1 = top-left x co-ordinate.
  • y1 = top-left y co-ordinate.
  • x2 = bottom-right x co-ordinate.
  • y2 = bottom-right y co-ordinate.


Return Value

  • NONE


Draw a rectangle between (16,16) and (100,41) in Black colour

#include <gfx.h>

void main()
   //Initialize ProGFX Engine

   //Draw a rectangle between (16,16) to (100,41) in Black colour

   //Update the display
glcd rectangle

Rectangle in GLCD

Drawing a Filled Rectangle in GLCD

In place of above function use the following function. It will draw a filled rectangle.

void GFXFillRect(UINT8 x1,UINT8 y1,UINT8 x2, UINT8 y2,UINT8 color);


Draw a filled rectangle between (16,16) and (100,41) in Black colour

#include <gfx.h>

void main()
   //Initialize ProGFX Engine

   //Draw a filled rectangle between 
   //(16,16) to (100,41) in Black colour

   //Update the display

glcd filled rectangle

Filled Rectangle in GLCD

Drawing a Circle in GLCD

Circle can be drawn on GLCD by specifying the center and the radius. The following function draws a circle in ProGFX.

void GFXCircle(UINT8 cx,UINT8 cy,UINT8 rad,UINT8 color);


  • cx = x co-ordinate of center.
  • cy = y co-ordinate of center.
  • rad = radius.
  • colour = either GFX_COLOR_BLACK or GFX_COLOR_WHITE

Return Value

  • NONE


Draw a circle with center at 64,32 and having a radius of 20 pixels in Black colour.

#include <gfx.h>

void main()
   //Initialize ProGFX Engine

   //Draw a circle with center at 64,32
   //and radius of 20 pixels.

   //Update the display


glcd circle drawing

Circle in GLCD

System Functions of ProGFX

void GFXInit();

This function Initialize the ProGFX Graphics Engine. Must be called before using any other graphic functions.


Return Value

void GFXUpdate();

This function transfers the internal graphic buffer to the LCD Module. After your drawing is complete you must call this to make it visible on screen.


Return Value

void GFXClear();

This function Clears the screen.


Return Value

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33 thoughts on “Interfacing Graphical LCD with AVR MCU – Part III

  • Pingback: Interfacing Graphical LCD with AVR MCU - Part II | eXtreme Electronics

  • Pingback: Interfacing KS0108 based 128x64 Graphical LCD with AVR Microcontroller. | eXtreme Electronics

  • By kiran - Reply

    Good tutorial ..In last tutorial you created library for Progfx with extension of .lib file how to creaate our own library can u give guide me

    • By Avinash - Reply


      In gcc compilers library has extension .a and NOT .lib

      Also when you downloaded WinAVR (avr-gcc) it comes with its own user manual which is very good. So why are you asking such silly things so as how to make a library if it is clearly given on the manuals ???

  • By Sayantan - Reply

    sir,can u please upload the custom characters tutorial for
    a 16×2 lcd (4-wire)module.I have been waiting for it long time.
    It would be great help for me,sir.Thank you.

  • By kiran - Reply

    Thank you Avinash..i didn’t read the user manual thats the problem ..any how thank you.. i will do it..

  • By Ramanpreet Singh - Reply

    Hi Avinash,
    It was an excellent tutorial. I was waiting for these tutorials ever since you said that GLCD tutorials are on their way.

  • By ANOOP KR - Reply

    Hai Avinash
    I saw your tutorial about the graphical LCD.Its amazing.congrats…I want to one thing that can i change the port pins that connecting with the graphic LCD.Or i should have to connect in the same manner as shown in the above circuit diagram.Please give me a solution. Thank you

  • By Sultan - Reply

    Amazing tutorials keep it up…

  • By Bang Ming - Reply

    Does the library works with a st7920? Thanks.

  • By Swaroop - Reply

    This is probably not the right place to say this, but, there is another IDE for AVR development called Visual Micro Lab and its awesome. It uses the same WinAVR backend, but it can simulate all kinds of devices that you would connect with an AVR (yes, even an LCD!!) along with the AVR. the website is : Best part is Its Free!!


    • By Avinash - Reply


      Ya, we know VMLab, use it and love it!

  • By srinath - Reply

    GFXRawPutPixel(32,24,GFX_COLOR_BLACK); will draw a pixel but how to erase the same pixel?
    is there any other command by which a drawn pixel can be erased?
    pls tell…..
    thanks in advance

    • By Avinash - Reply


      Common sense

  • By Harmandeep Singh - Reply

    Lovely work….Keep it up buddy…

  • By Ritesh Aggarwal - Reply

    I am interfacing the GLCD to the atmega128. The problem is that the left hand side of the display does not display anything. I have to press the reset button a couple of times to get it working. Can anybody suggest a solution?

  • By Savita - Reply

    Hello Avinash!!

    Hey i am looking for some driver code for interfacing this 128×64 graphics LCD with PIC24 . Do you have any idea about that. I would greatly appreciate if anyone help me.

    Savita Patil

  • By Ash - Reply

    i have a problem, my right half of the screen is shifted down by 4 pixel.. can u please tell me how to solve it?

  • By Victor Zaharia - Reply

    I am looking for some driver code or software, for interfacing 240×128 GLCD based T6963C. I find somewere from one site, but ar incomplete, is for LINUX OS, and are manny characteres in arabian languages.
    I want make one weather station with ATmega MCU, GLCD T6963C based 240×128, 2xDS18b20, SY-HS120, MPX2100AP, PCF8583P, wind meter and wind wane, and field high potencial detection.
    With PIC16F877A, I find from 3 sites, but not with previsiones weather, displaing pressiure for 72 hours before, and manny litle problems for one farmer with location in midle of the field, to 100 mile from first neighbours.
    Thank`s for your projects for beginners.

    • By Avinash - Reply

      Sorry bro you have to do it yourself !

  • By dhaval sheth - Reply

    hi i want to load bmp image on GLCD so i used this function
    and my image is stored in seq2.h file but there is no display image on me

  • By Trinayan - Reply

    Can u please tell me how to use a touchscreen mounted on a Glcd using avr…Please just give me an idea

  • By ArogyaReddy - Reply

    Dear Sir,
    i saw your tutorial, it is very nice,
    my small request to you is,

    i am using NXP’s P89V51RD2 microcontroler and JHD12864E graphic display, do you give me the c code to display characters in this display(128 by 64 display).

    Thanks and regards,
    Arogya Reddy

  • By OMKAR.AGASHE - Reply

    I want to interface GLCD Dev board with ADuC845 micro-controller do you have any board? or software programs to get an idea about interfacing .
    Sir I have interfaced my GLCD with above mentioned controller,but I am not able to use your fonts by adding Header files in program. my program is array based for accessing each pixel.PLEASE help me sir i am stuck with it as i cant use any of your features with ADuC845
    Thank you ,

  • By Arnab Chowdhury - Reply

    In this page the image “Pixel Addressing in 128×64 glcd” i think max(x,y) should be(127,63) because (x,y) starts from (0,0) not (1,1).

    • By Avinash - Reply


      Thank you for pointing out the mistake. It has been corrected.

  • By Deepak Nair - Reply

    Hello Avinash,

    I have been experimenting with the GLCD Development Board and find it very interesting. Is there someplace from where I can get the complete list of ProGFX functions (preferably with brief explanations)?

    Thanks and regards.

  • By vasudev - Reply

    nice tutorial 🙂

    • By Avinash - Reply



  • By shivam - Reply

    extremely helpful

  • By Balwinder - Reply

    Hello sir
    I am thankfull yo sir for very helpfull avr tutorials.
    sir i wnats to use progfx for graphical lcd interfacing
    but during compilation it shows the following errors
    Error 1 unknown type name ‘prog_uint8_t’
    Error 5 variable ‘Arial12’ must be const in order to be put into read-only section by means of ‘__attribute__((progmem))’
    Warning 6 ‘Arial12’ defined but not used [-Wunused-variable]

    please help me
    and how to change lcd pins

    • By Avinash - Reply


      You should be our customer to get any personal support.

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