c code for 2x8 lcd using pic16f877a

[ditch08]

Good day to all.

i'm having a difficult time trying to find out if my 2x8 lcd is functioning well. See, i'm currently testing it with a code which is intended for 2x16 lcd.
I'm using an mplab with hi-tech c compiler and PIC16F877A. I made some modifications at the code, followed the schematic diagrams and its connections but my display has always been blocks. I know testing the lcd with the code not intended for it is wrong but atleast it should have displayed any character right? I also tried sampled codes from hi-tech's sample folder but the result is always the same. So now, i don't know if the code is my problem or the lcd, or maybe both. If i can only test a decent code for this lcd using mplab with hi-tech compiler and still not display a thing, then i can assure to myself to throw away this lcd..

thanks

 

[nandhu015]

Post your code and schematic, Someone will find out the fault

my display has always been blocks

There are 2 things may cause this.

improper contrast & improper initialization. Check these...

 

[Jestin_cubetech]

please post 2x8 lcd datasheet.

 

[ditch08]

About the contrast, i connect a potentiometer to adjust it. But for the initialization, i am not sure since i am using a code for 16x2 lcd display. Maybe i'm doin something with that too. that's why i need a simple code to test it. Even the LCDemo sample from hi-tech c compiler was not working.

this is the datasheet i've search in the net, https://www.datasheets360.com/pdf/8012340707842815009?comp=3509

 

[andre_luis]

Try simulate on PROTEUS and this way you can determine if the problem is at the Hardware or at the Firmware.


+++

 

[ditch08]

Try simulate on PROTEUS and this way you can determine if the problem is at the Hardware or at the Firmware.


+++

well, i'm kind of limited to using mplab with hi-tech c compiler right now. But i'll try to download that. Can you give me a link? thanks

 

[Jestin_cubetech]

is it your lcd ?

 

[ditch08]

is it your lcd ?

Yes, that's the one

- - - Updated - - -

i was trying this code from sample folder of the hitech compiler for this LCD:

#include <htc.h>
#include "lcd.h"

void
main(void)
{
	lcd_init();
	lcd_goto(0);	// select first line
	lcd_puts("1234");
	lcd_goto(0x40);	// Select second line
	lcd_puts("Hello");

	for(;;);
}

/*
 *	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):
 *	
 *	PORTD bits 0-3 are connected to the LCD data bits 4-7 (high nibble)
 *	PORTA bit 3 is connected to the LCD RS input (register select)
 *	PORTA bit 1 is connected to the LCD EN bit (enable)
 *	
 *	To use these routines, set up the port I/O (TRISA, TRISD) then
 *	call lcd_init(), then other routines as required.
 *	
 */

#ifndef _XTAL_FREQ
 // Unless specified elsewhere, 4MHz system frequency is assumed
 #define _XTAL_FREQ 4000000
#endif


#include	<htc.h>
#include	"lcd.h"

#define	LCD_RS RA3
#define	LCD_RW RA2
#define LCD_EN RA1

#define LCD_DATA	PORTD

#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)
{
	__delay_us(40);
	LCD_DATA = ( ( c >> 4 ) & 0x0F );
	LCD_STROBE();
	LCD_DATA = ( c & 0x0F );
	LCD_STROBE();
}

/*
 * 	Clear and home the LCD
 */

void
lcd_clear(void)
{
	LCD_RS = 0;
	lcd_write(0x1);
	__delay_ms(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
	lcd_write( c );
}


/*
 * 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()
{
	char init_value;

	ADCON1 = 0x06;	// Disable analog pins on PORTA

	init_value = 0x3;
	TRISA=0;
	TRISD=0;
	LCD_RS = 0;
	LCD_EN = 0;
	LCD_RW = 0;
	
	__delay_ms(15);	// wait 15mSec after power applied,
	LCD_DATA	 = init_value;
	LCD_STROBE();
	__delay_ms(5);
	LCD_STROBE();
	__delay_us(200);
	LCD_STROBE();
	__delay_us(200);
	LCD_DATA = 2;	// Four bit mode
	LCD_STROBE();

	lcd_write(0x28); // Set interface length
	lcd_write(0xF); // Display On, Cursor On, Cursor Blink
	lcd_clear();	// Clear screen
	lcd_write(0x6); // Set entry Mode
}

i followed the instructions on the pin connections but the result was always block. Do you think it's the controller? :/

 

[Raady Here]

Try switching on LED back light first so that you can understand if the display is working or not(if connections are tightly connected).

 

[jayanth.devarayanadurga]

Post your exact circuit. See if ADCON1 or ANSELx registers have to be configured to make pins digital.

 

[Jestin_cubetech]

1, add delay in lcd strobe 
    #define	LCD_STROBE	LCD_EN = 1;__delay_ms(1); LCD_EN=0;
2, add delay after each lcd write operation 

  lcd_write(unsigned char c)
  {
	LCD_DATA = ( ( c >> 4 ) & 0x0F );
	LCD_STROBE();
	LCD_DATA = ( c & 0x0F );
	LCD_STROBE;
        __delay_us(100);
}

3, lcd_init()
{

	ADCON1 = 0x06;	// Disable analog pins on PORTA
	TRISA=0;	TRISD=0;

	LCD_RS = 0;
	LCD_EN = 0;
	LCD_RW = 0;
	
__delay_ms(15);	// wait 15mSec after power applied,
LCD_DATA	 = 0x3;
LCD_STROBE();
__delay_ms(5);

	LCD_DATA = 2;	// Four bit mode
	LCD_STROBE();
__delay_ms(5);

	lcd_write(0x28); // Set interface length
__delay_ms(5);
	lcd_write(0xF); // Display On, Cursor On, Cursor Blink
__delay_ms(5);
	lcd_write(0x6); // Set entry Mode
}