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How to shift message from left to right

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Parth86

Member
Hi
I am using 8051 MCU and keil software. How to shift message from left to right and then right to left in program

C:
// Program for LCD Interfacing with 8051 Microcontroller

#include<reg51.h>
#define display_port P1                    //Data pins connected to port 2 on microcontroller
sbit rs  =  P2^0;                                    //RS pin connected to pin 2 of port 3
sbit rw  =  P2^1;                                   // RW pin connected to pin 3 of port 3
sbit e  =  P2^2;                                    //E pin connected to pin 4 of port 3

void msdelay(unsigned int time)  // Function for creating delay in milliseconds.
{
    unsigned   i,  j ;
    for(i = 0;  i <  time;   i++)
    for(j  =  0; j  <  1275;  j++);
}
void lcd_cmd(unsigned char command)  //Function to send command instruction to LCD
{
    display_port  =  command;
    rs  =  0;
    rw  =  0;
    e  =  1;
    msdelay(1);
    e  =  0;
}

void lcd_data(unsigned char disp_data)  //Function to send display data to LCD
{
    display_port  =  disp_data;
    rs  =  1;
    rw  =  0;
    e  =  1;
    msdelay(1);
    e  =  0;
}

 void lcd_init()                  //Function to prepare the LCD  and get it ready
{
    lcd_cmd(0x38);           // for using 2 lines and 5X7 matrix of LCD
    msdelay(10);
    lcd_cmd(0x0F);          // turn display ON, cursor blinking
    msdelay(10);
    lcd_cmd(0x01);         //clear screen
    msdelay(10);
    lcd_cmd(0x81);        // bring cursor to position 1 of line 1
    msdelay(10);
}
void main()
{
      unsigned  char  a[15] = "ELECTRO-TECH";       //string of 14 characters with a null terminator.
      int  l = 0;
    lcd_init();
    while ( a[l]   !=  '\0')                                                   // searching the null terminator in the sentence
    {
        lcd_data(a[l]);
        l++;
        msdelay(50);
    }
}
 

Pommie

Well-Known Member
Most Helpful Member
A quick guess to get you started.
Code:
void main()
{
    unsigned  char  a[16] = "ELECTRO-TECH    ";       //string of 14 characters with a null terminator.
    char i;
    lcd_init();
    while (1){
        char temp;
        //scroll in memory and display
        lcd_cmd(0x80);        //set to start of display
        temp=a[0];
        for(i=0;i<15;i++){
            a[i]=a[i+1];
            lcd_data(a[i]);
        }
        //do final character
        a[15]=temp;
        lcd_data(temp);
        msdelay(50);
    }
}
Mike.
 
Last edited:

Ian Rogers

User Extraordinaire
Forum Supporter
Most Helpful Member
You need this function...
C:
void Lcdprint(char* str)
   {
   while(*str != 0)
      lcd_data(*str++);
   }
This will draw a line of text on the screen.. Then manipulate the string before the LCD write.
C:
char lcd_buffer[17]  = {"Electro - tech  "};

void rotateleft(void)
   {
   char temp;
   temp = lcdbuffer[0];
   for( x = 1;x<16,x++)
      {
      lcdbuffer[x] = lcdbuffer[x+1];
      }
   lcdbuffer[16]=temp;
   lcdbuffer[17] = 0;

   Lcd_print(lcdbuffer);
   }
using a buffer should minimise flicker!! **THESE ROUTINES ARE UNTESTED**
 

Pommie

Well-Known Member
Most Helpful Member
I figured that shifting and then writing would not be necessary as the write to LCD is the slowest part, 1mS in this case.

Mike.
 

Parth86

Member
You need this function...
C:
void Lcdprint(char* str)
   {
   while(*str != 0)
      lcd_data(*str++);
   }
This will draw a line of text on the screen.. Then manipulate the string before the LCD write.
C:
char lcd_buffer[17]  = {"Electro - tech  "};

void rotateleft(void)
   {
   char temp;
   temp = lcdbuffer[0];
   for( x = 1;x<16,x++)
      {
      lcdbuffer[x] = lcdbuffer[x+1];
      }
   lcdbuffer[16]=temp;
   lcdbuffer[17] = 0;

   Lcd_print(lcdbuffer);
   }
using a buffer should minimise flicker!! **THESE ROUTINES ARE UNTESTED**
You are making two separate routine rotateleft and rotateleft but I already have data routine lcd_data. if I replace my routine with your. I am getting error. What should be in main program ?
 

Ian Rogers

User Extraordinaire
Forum Supporter
Most Helpful Member
C:
char lcdbuffer[17]  = {"Electro - tech  "};
void msdelay(unsigned int time)  // Function for creating delay in milliseconds.
{
    unsigned   i,  j ;
    for(i = 0;  i <  time;   i++)
    for(j  =  0; j  <  75;  j++);
}
void lcd_cmd(unsigned char command)  //Function to send command instruction to LCD
{
    display_port  =  command;
    rs  =  0;
    rw  =  0;
    e  =  1;
    msdelay(1);
    e  =  0;
}
void lcd_data(unsigned char disp_data)  //Function to send display data to LCD
{
    display_port  =  disp_data;
    rs  =  1;
    rw  =  0;
    e  =  1;
    msdelay(1);
    e  =  0;
}
void Lcd_print(char* str)
   {
   while(*str != 0)
      lcd_data(*str++);
   }
 void lcd_init()                  //Function to prepare the LCD  and get it ready
{
     msdelay(20);
    lcd_cmd(0x38);           // for using 2 lines and 5X7 matrix of LCD
    msdelay(10);
    lcd_cmd(0x0C);          // turn display ON, cursor blinking
    msdelay(10);
    lcd_cmd(0x06);         //clear screen
    msdelay(10);
    lcd_cmd(0x1);        // bring cursor to position 1 of line 1
    msdelay(10);
}
void rotateRight(void)
   {
   char temp, x;
   temp = lcdbuffer[15];
   for( x = 15;x >0 ;x--)
      {
      lcdbuffer[x] = lcdbuffer[x-1];
      }
   lcdbuffer[0]=temp;
   lcdbuffer[16] = 0;
   lcd_cmd(0x80);
   Lcd_print(lcdbuffer);
   msdelay(200);
   }
void rotateleft(void)
   {
   char temp,x;
   temp = lcdbuffer[0];
   for( x = 0;x<15;x++)
      {
      lcdbuffer[x] = lcdbuffer[x+1];
      }
   lcdbuffer[15]=temp;
   lcdbuffer[16] = 0;
   lcd_cmd(0x80);
   Lcd_print(lcdbuffer);
   msdelay(200);
   }
void main()
   {
   
   int  i ;
   lcd_init();
   Lcd_print(lcdbuffer);  
   while(1) 
      {    
      msdelay(1000);
      i = 16;
      while(i--)   
  rotateleft();                                           // searching the null terminator in the sentence
      msdelay(1000);
      i=16;
      while(i--)   
  rotateRight();
     
      }
   }
Had to mess up your delay function as mine runs at 12Mhz..

Also I have left off the definitions as mine were different.
 

be80be

Well-Known Member
Here the whole ball of wax from the iink I posted
Code:
#include<reg51.h>
sbit rs=P3^5;   //Register select (RS)
sbit en=P3^6;   //Enable (EN) pin
sbit rw=P3^7;   //Read write (RW) pin
char text[]={"microcntroler-project.com           "};

void delay(unsigned int time)  //Time delay function
{
unsigned int i,j;
for(i=0;i<time;i++)
for(j=0;j<5;j++);
}

             //Function for sending values to the command register of LCD
void lcdcmd(unsigned char value) 
{
P1=value;
rs = 0;
    rw = 0;
    en = 1;
delay(50);
en=0;
delay(50);

}
             //Function for sending values to the data register of LCD
void display(unsigned char value) 
{
P1=value;
rs = 1;
rw = 0;
en = 1;
delay(500);
en=0;
delay(50);

}
             //function to initialize the registers and pins of LCD
             //always use with every lcd of hitachi
void lcdint(void)         
{
P1=0x00;    //Port 1 is used as output port             
P3=0x03;    //Port 3 higher bits from 2 to 7 are used as output and lower two bits are used to activate UART 
     delay(15000);
     display(0x30);
     delay(4500);
     display(0x30);
     delay(300);
     display(0x30);
     delay(650);
lcdcmd(0x38);
delay(50);
lcdcmd(0x0F);
delay(50);
lcdcmd(0x01);
delay(50);
lcdcmd(0x06);
delay(50);
lcdcmd(0x8F);
delay(50);
}

void main()
{
unsigned int i;

lcdint();
 i=0;
while(text[i]!='\0'){
 display(text[i]);
 delay(200);
 lcdcmd(0x18);
 delay(600);
 i++;
}

}
 
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