Using LCD Module with AVRs

When you start working with LCD modules you will start feeling the real power of MCU and your imaginations will be touching sky you will wonder how many exciting a powerful gadgets you can create and that’s so very easily.

LCD Modules can present textual information to user. It’s like a cheap “monitor” that you can hook in all of your gadgets. They come in various types. The most popular one can display 2 lines of 16 characters. These can be easily interfaced to MCU's, thanks to the API( Functions used to easily access the modules) we provide. LCD interfacing is just fun !

Fig: A 16x2 LCD Module

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PIN Configurations.

The lcd modules has 16 PINs for interfacing. The details are given below.

Connection with Board MINI.

The lcd module can be easily connected to the Board™ MINI the connection is as follows.

Fig: Connection

Adding LCD support to your project

Fig: Adding files to projects.

Programming.

In your main C file include the file lcd.h as #include “lcd.h” then initialize the LCD subsystem using a call to LCDInit(LS_BLINK|LS_ULINE); the argument specify the type of cursor required the LS_BLINK gives a blinking cursor. LS_ULINE gives a underlined cursor. To write any text call LCDWriteString("Welcome"); To write any number call void LCDWriteInt(int val,unsigned int field_length); This will print a integer contained in “val” . The field length is the length of field in which the number is printed.

For example LCDWriteInt(3,4); will print as follows

While LCDWriteInt(123,5) will print as follows.

To goto any particular position on screen call.

Fig: Cursor Positioning.

Now anything you write to LCD will be printed at (11,1).

Clearing the display

LCDWriteStringXY(x,y,msg); ____________________________ x,y : the location where to print “msg” msg : the message to print Ex: LCDWriteStringXY(3,0,”hello”); LCDWriteStringXY(8,1,”world”); Output: Fig: Cursor Positioning.

LCDWriteIntXY(x,y,num,field_length);
____________________________________
x,y : the location where to print “num”
num : the integer number to print  
field_length : the length of field (see LCDWriteInt() function above).

Sample Program

#include <avr/io.h>
#include <util/delay.h>

#include "lcd.h"

void main()
{
   unsigned char i;

   //Initialize LCD module
   InitLCD(LS_BLINK|LS_ULINE);

   //Clear the screen
   LCDClear();

   //Simple string printing
   LCDWriteString("Congrats ");

   //A string on line 2
   LCDWriteStringXY(0,1,"Loading ");

   //Print some numbers
   for (i=0;i<99;i+=1)
   {
      LCDWriteIntXY(9,1,i,3);
      LCDWriteStringXY(12,1,"%");
      _delay_loop_2(0);
      _delay_loop_2(0);
      _delay_loop_2(0);
      _delay_loop_2(0);

   }

   //Clear the screen
   LCDClear();

   //Some more text

   LCDWriteString("Hello world");
   LCDWriteStringXY(0,1,"By YourName Here");    // <--- Write ur NAME HERE !!!!!!!!!!!

   //Wait
   for(i=0;i<100;i++) _delay_loop_2(0);

   //Some More ......
   LCDClear();
   LCDWriteString("    eXtreme");
   LCDWriteStringXY(0,1,"  Electronics");

}

Advance Use – Configuring Connections.

Fig: Configuring LCD Connection.

Set LCD_DATA to the port where you have connected the LCD data lines. Data Lines must be connected to any port say PORTB starting from pin-0 to pin-3. i.e. If you set #define LCD_DATA B you should connect like this :

PORTB.0->DATA4 PORTB.1->DATA5 PORTB.2->DATA6 PORTB.3->DATA7

The library uses advance 4-bit mode so DATA0-DATA-3 of LCD are not used, saving 4 MCU pins! Now set the port where you have connected LCD’s ‘E’ signal. In example it is PORTD so #define LCD_E D Then specify to which PIN of PORTD it is connected, this is done by #define LCD_E_POS PD6 So ‘E’ pin of LCD is connected to PORTD-6 In same way set RS and RW signals. And that’s all! So you saw how easy is to customize the library.

Downloads

• Download this tutorials with all required files.(library and sample code included)

Going Graphical ?

If you have more sophisticated display requirement then you may go for Graphical LCDs (GLCD) they can render graphics like Icons and bitmaps (images), support graphic primitives like line,circle, rectangle etc. Also they can draw text in different fonts and sizes. That means 100% fun! And they are cheap and very easy to get started (thanks to ProGFX.org). We have some beginners tutorials for it too. So why waiting? Go Graphical!

• http://extremeelectronics.co.in/avr-tutorials/interfacing-ks0108-based-128x64-graphical-lcd-with-avr-mcu/

Have fun and don’t forget to bookmark this page. If you think this tutorial has helped you please post a comment.