[SOLVED] LCD 4 bit mode interfacing

[hemnath]

Hardware: PIC18F2520
Microcontroller pins B0 to B3 connected LCD DB4 to DB7;
A2 connected to RS
A1 connected to Enable

CCS C compiler program:

#include "18F2520.h" 
#fuses  INTRC_IO 
#use delay(clock=4000000) 

#define EN     PIN_A1
#define RS     PIN_A2

void lcd_init(); 
void lcd_cmd(unsigned char ); 
void lcd_data(unsigned char ); 
void disp_cmd(unsigned char ); 
void disp_data(unsigned char ); 


void main() 
{ 
   delay_ms(100); 
   lcd_init(); 
   delay_ms(100); 

   while(1) 
   { 
      disp_cmd(0x80); 
      printf(disp_data, "TESTING "); 
      delay_ms(100); 
   } 
} 

void lcd_init() 
{ 
   disp_cmd(0x02);      // To initialize LCD in 4-bit mode. 
   disp_cmd(0x20);      // To initialize LCD in 1 lines, 5x7 dots and 4bit mode. 
   disp_cmd(0x0C); 
   disp_cmd(0x01); 
   disp_cmd(0x06); 
   disp_cmd(0x80); 
} 

void lcd_cmd(unsigned char c) 
{ 
   output_b(c); 
   output_low(RS); 
   output_high(EN); 
   delay_ms(15); 
   output_low(EN); 
} 

void lcd_data(unsigned char z) 
{ 
   output_b(z); 
   output_high(RS); 
   output_high(EN); 
   delay_ms(15); 
   output_low(EN); 
} 

void disp_cmd(unsigned char cmd_value) 
{ 
   unsigned char cmd_value1; 
   cmd_value1 = ((cmd_value>>4) & 0x0F);   // Shift 4-bit and mask 
   lcd_cmd(cmd_value1);               // Send to LCD 
   cmd_value1=(cmd_value & 0x0F); 
   lcd_cmd(cmd_value1);               // Send to LCD 
} 

void disp_data(unsigned char data_value) 
{ 
   unsigned char data_value1; 
   data_value1 = ((data_value>>4) & 0x0F); 
   lcd_data(data_value1); 
   data_value1=(data_value & 0x0F); 
   lcd_data(data_value1); 
}

But the display shows nothing. Voltages are +5V. Please help .

 

[KlausST]

Hi,

LCD drive voltage pin to adjust contrast is not connected.

Klaus

 

[hemnath]

PIN 3 is connected to potentiometer. When Checking with 4 bit mode using PINS B4 to B7 it is working. But when I use B0 to B3 it is not working.

 

[arun_190175]

PIN 3 is connected to potentiometer. When Checking with 4 bit mode using PINS B4 to B7 it is working. But when I use B0 to B3 it is not working.

only B4-B7 are working in 4 bit