Interfacing PIC18LF4550 to 16x2 LCD

[Akhil Mohan]

Hello,

I am trying to interface a PIC18LF4550 with a 16x2 LCD display (h as a JHD162A Processor) in the 4 bit mode. I have done some modifications to the code that I got from PyroElectro.com, but, the display shows nothing and am not sure where is the mistake. Could you please help me to resolve this ?

#include <htc.h>
#include<delays.h>
#include <pic18F4550.h>

#define E_PIN    PORTDbits.RD6   /* PORT for E  */
#define RW_PIN   PORTDbits.RD5   /* PORT for RW */
#define RS_PIN   PORTDbits.RD4   /* PORT for RS */
#define _XTAL_FREQ 20000000
__CONFIG (1, FOSC_HS);
__CONFIG (2, WDTDIS & PWRTEN & BOREN & LVPEN);

void prnt(unsigned int);
void commd(unsigned int);
void lcd_init(void);
void Delay10KTCYx(unsigned char unit); 
void Delay1KTCYx(unsigned char unit);

void main(void)
{

   int count=0;

   int marquee_1 = 0;
   int dir_1 = 0;

   char output[] = " Hello ";
   char output2[] = " World !! ";

   TRISD=0x00;
   PORTD=0x00;

   Delay10KTCYx(200); // After Power On, this instruction will give 16ms delay

   lcd_init();

   while(output[count] != '\0')
   {
   prnt(output[count]);
   count++;
   }

   commd(0b11000000);   //Move 2nd Next Line

   count = 0;
   while(output2[count] != '\0')
   {
   prnt(output2[count]);
   count++;
   }

   commd(0b10000000);

   while(1)
   {

   if(marquee_1 == 0)
      dir_1 = 1;

   if(marquee_1 == 9)
      dir_1 = 0;

   if(dir_1)
        {
      commd(0b00011100);
      marquee_1++;
   }
   else
        {
      commd(0b00011000);
      marquee_1--;
   }

   Delay10KTCYx(200);

   }

}

void lcd_init(void)
{
E_PIN = 0;
RS_PIN = 0;
RW_PIN = 0;

commd(0b00100000); // 

commd(0b00101100); // Function Set

commd(0b00001000); // Display OFF

commd(0b00000001); // Display Clear

commd(0b00000110); // Entry Mode Set
}


//4-bit print interface

void prnt(unsigned int character)
{

PORTD=character >> 4;

RS_PIN = 1;
RW_PIN = 0;
E_PIN = 1;
E_PIN = 0;

PORTD=character & 0x0f;

RS_PIN = 1;
RW_PIN = 0;
E_PIN = 1;
E_PIN = 0;

Delay1KTCYx(200);
//Delay1KTCYx(1); //The Delay Above Is Only To
              //Create The Type-Writer Effect

}


//4-bit instruction interface

void commd(unsigned int commd)
{

PORTD=commd >> 4;
RS_PIN = 0;
RW_PIN = 0;
E_PIN = 1;
E_PIN = 0;

PORTD=commd &0x0f;
RS_PIN = 0;
RW_PIN = 0;
E_PIN = 1;
E_PIN = 0;

Delay1KTCYx(10);

}

Thanks in advance
Akhil

 

[Golden Electronics]

1. Keep RW always low
2. Insert small delay between Enable signal high to low.
3. After each write command or data insert some ms delay. At start keep this delay high. After working u may reduce it.

 

[paulfjujo]

hello,

Your wiring is abfull !
why mixing bits for LCD data ?
use a quartet of bits for the LCD DATA ie: RD0..RD3 or RD4..RD7
and other bits for LCD control..


Your LCD init sequence is wrong ....
there is plenty of example on this forum ...for a good LCD Init. in 4 bits mode.

 

[Akhil Mohan]

Thanks for your suggestion, got it working last day