lcd with pic 16f876a in C

[neelam29]

dear all
iwant to interface a lcd 2X 16 line hd44780 with pic16f876a using HITECH C .i am not able to get anything written on the screen. i am sendimng the code .please check wht is the mistake.

Code:
/*
* LCD interface example
* Uses routines from delay.c
* This code will interface to a standard LCD controller
* like the Hitachi HD44780. It uses it in 4 bit mode, with
* the hardware connected as follows (the standard 14 pin
* LCD connector is used):
*
* PORTB bits 0-3 are connected to the LCD data bits 4-7 (high nibble)
* PORTA bit 2 is connected to the LCD RS input (register select)
* PORTA bit 3 is connected to the LCD EN bit (enable)
*
* To use these routines, set up the port I/O (TRISA, TRISB) then
* call lcd_init(), then other routines as required.
*
*/

#include <pic.h>

#include "lcd.h"
#include "delay.h"

__CONFIG(0x3F76);
static bit LCD_RS @ ((unsigned)&PORTA*8+2); // Register select
static bit LCD_EN @ ((unsigned)&PORTA*8+3); // Enable



#define LCD_STROBE ((LCD_EN = 1),(LCD_EN=0))


/* write a byte to the LCD in 4 bit mode */

void lcd_write(unsigned char c)
{
PORTB = (PORTB & 0xF0) | (c >> 4);
LCD_STROBE;
PORTB = (PORTB & 0xF0) | (c & 0x0F);
LCD_STROBE;
DelayUs(40);
}

/*
* Clear and home the LCD
*/

void lcd_clear(void)
{
LCD_RS = 0;
lcd_write(0x1);
DelayMs(2);
lcd_write(0x2);
DelayMs(2);
}

/* write a string of chars to the LCD */

void lcd_puts(const char * s)
{
LCD_RS = 1; // write characters
while(*s)
lcd_write(*s++);
}

/* write one character to the LCD */

void lcd_putch(char c)
{
LCD_RS = 1; // write characters
PORTB = (PORTB & 0xF0) | (c >> 4);
LCD_STROBE;
PORTB = (PORTB & 0xF0) | (c & 0x0F);
LCD_STROBE;
DelayUs(40);
}


/*
* Go to the specified position
*/

void lcd_goto(unsigned char pos)
{
LCD_RS = 0;
lcd_write(0x80+pos);
}

/* initialise the LCD - put into 4 bit mode */

void lcd_init(void)
{
LCD_RS = 0; // write control bytes
DelayMs(15); // power on delay
PORTB = 0x3; // attention!
LCD_STROBE;
DelayMs(5);
LCD_STROBE;
DelayUs(100);
LCD_STROBE;
DelayMs(5);
PORTB = 0x2; // set 4 bit mode
LCD_STROBE;
DelayUs(40);
lcd_write(0x28); // 4 bit mode, 1/16 duty, 5x8 font
lcd_write(0x08); // display off
lcd_write(0x0F); // display on, blink curson on
lcd_write(0x06); // entry mode
}


void main(void)
{
TRISA = 0x00; // control lines are output
PORTA = 0x00; // control lines are output
TRISB = 0x00; // Make all Port B data lines output
PORTB = 0x00; // Make all Port B data lines output

lcd_init();
while(1)
{
lcd_goto(0x04);
lcd_putch('A');
}
}

 

[Nigel Goodwin]

I suggest you add a contrast control, without it you might not see anything!, if it's too low you get nothing, and if it's too high you get solid black blocks.

Can't help you with C though!.

 

[philba]

use a potentiometer for Vee. tie one end to +5, the other end to gnd and the wiper into the Vee pin on the LCD. adjust it until you see pixels and back it off a bit.

One thing to be aware of, some LCDs ("extended temperature") need negative Vee. kind of sucks. do you have the datasheet to verify this.

does the new forum software have a way to display code? very annoyiung to have to read C code with no indentation. I won't read code like that. sorry.