HELP: Interfacing LCD with PIC18f4520 (MpLab C18 Compiler)

Ayie29 · Mar 15, 2012

Currently doing for my final year project and want to test my lcd qy1602a with simple program. I had construct the circuit and coding like in this thread: https://www.electro-tech-online.com/threads/pic-18f4550-2x8-lcd-character-display-assistance.122251/

It cant work in proteus and my hardware. I using pickit2 as my programmer. isnt any setting that i miss out?

I had change abit in the coding as i want to use external oscillator.

Code:

[CODE]//turns watch dog timer off, turn low voltage programming off
#pragma config WDT=OFF, LVP=OFF, DEBUG=ON, MCLRE = OFF

#pragma config OSC=HS
 
#include <p18f4520.h>
#include <delays.h>

#define _XTAL_FREQ 10000000
 
//LCD (PortD)
#define  E            LATDbits.LATD6
#define  R_W       LATDbits.LATD5 
#define  RS          LATDbits.LATD4
#define  LCDdata LATD
 
void command(unsigned char);
void write(unsigned char);
void Nybble(unsigned char);
void init(void);
void PutMessage(rom char *);
 
void main()
{
	while(!OSCCONbits.IOFS);      //wait for osc stable
   	ADCON1 = 0x0F;                //make RA0 digital
 
    //data direction registers all 0's mean that all pins are set to output
	//all 1's means that all of the pins are set to operate as inputs
	TRISA = 0x00;  
	TRISB = 0x00; 
	TRISD = 0x00;
        init();
        PutMessage("Hello World!");
        command(0xc0);
        PutMessage("WELCOME");
        while(1);
}
 
//Write a string to the LCD
void PutMessage(rom char *Message)
{
	rom char *Pos = Message;
	while(*Pos!=0)
	    write(*Pos++);
}
 
/**********************************************************/
//4-bit methods for LCD
/**********************************************************/
void command(unsigned char i)
{
	RS =0;
	R_W =0;          //R/W=LOW : Write
	Nybble(i>>4);    //Send upper 4 bits
	Nybble(i);       //Send lower 4 bits
	Delay1KTCYx(2);  //must wait at least 2mS (2*1000*4/1e6 = 8ms used)
}
 
void write(unsigned char i)
{
	RS =1;
	R_W =0;          //R/W=LOW : Write
	Nybble(i>>4);    //Send upper 4 bits
	Nybble(i);       //Send lower 4 bits
	Delay1KTCYx(2);  //must wait 2mS
}
 
/**********************************************************/
void Nybble(unsigned char dat)
{
    dat &= 0x0f;             //clear top bits of dat
    LCDdata &= 0xf0;         //clear bottom bits of port (interested only in DB7-DB4)
    LCDdata |= dat;          //or the two and store at port
    E = 1;
    Delay1TCY();             //enable pulse width >= 300ns (used 4uS)
    E = 0;                   //Clock enable: falling edge
}
 
/**********************************************************/
void init(void)
{
    LCDdata=0x00; 
    Delay1KTCYx(15);    //Wait >15 msec after power is applied (used 20mS)
    Nybble(0x3); 	//command 0x30 = Wake up
    Delay1KTCYx(5);     //must wait 160us, busy flag not available (used 160uS)
    Nybble(0x3); 	//command 0x30 = Wake up #2
    Delay1KTCYx(5); 	//must wait 160us, busy flag not available (used 160uS) 
 
    command(0x20);      //Function set: 4-bit/2-line
    command(0x2c);      //Function set: 4-bit/2-line
    command(0x10);      //Set cursor
    command(0x01);      //Clear Display (Added)
    command(0x06);      //Entry Mode set
    command(0x0c);
}
/**********************************************************/
//End methods for LCD
/**********************************************************/

[/CODE]

View attachment 62167

Ian Rogers · Mar 15, 2012

You have changed processors... The pic18F4520 doesn't have oscconbits.... its stuck here..

Ayie29 · Mar 15, 2012

Ian Rogers said:
You have changed processors... The pic18F4520 doesn't have oscconbits.... its stuck here..

so now is the oscillator configuration problem? any solutions?

Ian Rogers · Mar 15, 2012

Just remove this line

Code:

while(!OSCCONbits.IOFS);      //wait for osc stable

There is also a small problem with the "rom char* ... rename it to "const rom char*"

Once that is out of the way you'll need to work on your delays.... they are all too small... There's an issue initialising the LCD...

Sorry for being vague... I would show you, but I'll have to finish work first..

Ayie29 · Mar 15, 2012

It's ok. I'm new to all these. thanks for your patience in teaching me. the delays how to change? my proteus still din show anything.

Ian Rogers · Mar 15, 2012

Ok I'm at home now... I'll shove it on Proteus and see what happens.

Code:

void init(void)
{
    LCDdata=0x00; 
    Delay1KTCYx(40);    //Wait >15 msec after power is applied (used 20mS)
    Nybble(0x3); 	//command 0x30 = Wake up
    Delay1KTCYx(15);     //must wait 160us, busy flag not available (used 160uS)
    Nybble(0x2); 	//command 0x30 = Wake up #2
    Delay1KTCYx(15); 	//must wait 160us, busy flag not available (used 160uS) 

    command(0x2C);      //Function set: 4-bit/2-line
    command(0xC);      //Set cursor
    command(0x06);      //Entry Mode set
    command(0x01);
}

Use this to initialize the LCD (remember to change the other issues I mentioned)

Ayie29 · Mar 15, 2012

Thanks Ian. My proteus finally work on these code! Now gonna proceed to hardware for real try. If work at proteus, isnt mean that work on hardware also?

My final coding:

Code:

//turns watch dog timer off, turn low voltage programming off
#pragma config WDT=OFF, LVP=OFF, DEBUG=ON, MCLRE = OFF
 
#pragma config OSC=HS
#define _XTAL_FREQ 20000000

#include <p18f4520.h>
#include <delays.h>
 

//LCD (PortD)
#define  E LATDbits.LATD6
#define  R_W LATDbits.LATD5 
#define  RS  LATDbits.LATD4
#define LCDdata LATD
 
 
void command(unsigned char);
void write(unsigned char);
void Nybble(unsigned char);
void init(void);
void PutMessage(const rom char *);
 
void main()
{   
   	ADCON1 = 0x0F;                //make RA0 digital
 
       //data direction registers all 0's mean that all pins are set to output
	//all 1's means that all of the pins are set to operate as inputs
	TRISA = 0x00;  
	TRISB = 0x00; 
	TRISD = 0x00;
        init();
        PutMessage(" Hello World!");
        command(0xc0);
        PutMessage(" WELCOME");
        while(1);
}
 
//Write a string to the LCD
void PutMessage(const rom char *Message)
{
const rom char *Pos = Message;
	while(*Pos!=0)
	    write(*Pos++);
}
 
/**********************************************************/
//4-bit methods for LCD
/**********************************************************/
void command(unsigned char i)
{
	RS =0;
	R_W =0;          //R/W=LOW : Write
	Nybble(i>>4);    //Send upper 4 bits
	Nybble(i);       //Send lower 4 bits
	Delay1KTCYx(2);  //must wait at least 2mS (2*1000*4/1e6 = 8ms used)
}
 
void write(unsigned char i)
{
	RS =1;
	R_W =0;          //R/W=LOW : Write
	Nybble(i>>4);    //Send upper 4 bits
	Nybble(i);       //Send lower 4 bits
	Delay1KTCYx(2);  //must wait 2mS
}
 
/**********************************************************/
void Nybble(unsigned char dat)
{
    dat &= 0x0f;             //clear top bits of dat
    LCDdata &= 0xf0;         //clear bottom bits of port (interested only in DB7-DB4)
    LCDdata |= dat;          //or the two and store at port
    E = 1;
    Delay1TCY();             //enable pulse width >= 300ns (used 4uS)
    E = 0;                   //Clock enable: falling edge
}
 
/**********************************************************/

void init(void)
{
    LCDdata=0x00; 
    Delay1KTCYx(40);    //Wait >15 msec after power is applied (used 20mS)
    Nybble(0x3); 	//command 0x30 = Wake up
    Delay1KTCYx(15);     //must wait 160us, busy flag not available (used 160uS)
    Nybble(0x2); 	//command 0x30 = Wake up #2
    Delay1KTCYx(15); 	//must wait 160us, busy flag not available (used 160uS) 
 
    command(0x2C);      //Function set: 4-bit/2-line
    command(0xC);      //Set cursor
    command(0x06);      //Entry Mode set
    command(0x01);
}
/**********************************************************/
//End methods for LCD
/**********************************************************/

View attachment 62213

ivan21 · Apr 30, 2012

thanks for sharing!

markort4211 · Aug 27, 2012

Hello, do you know how to send a int value on the LCD ?

Ian Rogers · Aug 27, 2012

What Language?..... What chip?.. What LCD?..

markort4211 · Aug 28, 2012

PIC 18f4550, C18 compiler, I create simulation in proteus and put lcd 16x2.

Ian Rogers · Aug 28, 2012

There are two ways.... Firstly, have you included the LCD routines <XLCD.H>?

If you want to output an integer you need to convert it to ascii first. Then you either write your own output function, or you use printf() or sprintf().

I use sprintf() as its easier for me... If you use printf() you need to specify....

Code:

stdout = _H_USER

at the beginning of your code. Then write a function

Code:

void _user_putc(unsigned char ch)
   {
   WriteDataXLCD(ch);
   }

xabi · Sep 26, 2012

hi

i am using pic18f4620 and using c18
i having problem initialize the lcd
the lcd only shows blackscreen

attached is the lcd datasheet

xabi · Sep 26, 2012

is there something i miss out?
appreciate help
thx

Ian Rogers · Sep 27, 2012

Your code!!! Your schematic!!! We can't guess the problem, there are MANY reasons why the screen wont work

xabi · Sep 27, 2012

my apologies
i did not mention i copy Ayie29 codes
my output port also the same as Ayie29

only the micro controller is different

Code:

//turns watch dog timer off, turn low voltage programming off
#pragma config WDT=OFF, LVP=OFF, DEBUG=ON, MCLRE = OFF
 
#pragma config OSC=HS
 
#include <p18f4620.h>
#include <delays.h>
 
 
//LCD (PortD)
#define  E LATDbits.LATD6
#define  R_W LATDbits.LATD5 
#define  RS  LATDbits.LATD4
#define LCDdata LATD
 
 
void command(unsigned char);
void write(unsigned char);
void Nybble(unsigned char);
void init(void);
void PutMessage(const rom char *);
 
void main()
{   
   	ADCON1 = 0x0F;                //make RA0 digital
 
       //data direction registers all 0's mean that all pins are set to output
	//all 1's means that all of the pins are set to operate as inputs
	TRISA = 0x00;  
	TRISB = 0x00; 
	TRISD = 0x00;
        init();
        PutMessage(" Hello World!");
        command(0xc0);
        PutMessage(" WELCOME");
        while(1);
}
 
//Write a string to the LCD
void PutMessage(const rom char *Message)
{
const rom char *Pos = Message;
	while(*Pos!=0)
	    write(*Pos++);
}
 
/**********************************************************/
//4-bit methods for LCD
/**********************************************************/
void command(unsigned char i)
{
	RS =0;
	R_W =0;          //R/W=LOW : Write
	Nybble(i>>4);    //Send upper 4 bits
	Nybble(i);       //Send lower 4 bits
	Delay1KTCYx(2);  //must wait at least 2mS (2*1000*4/1e6 = 8ms used)
}
 
void write(unsigned char i)
{
	RS =1;
	R_W =0;          //R/W=LOW : Write
	Nybble(i>>4);    //Send upper 4 bits
	Nybble(i);       //Send lower 4 bits
	Delay1KTCYx(2);  //must wait 2mS
}
 
/**********************************************************/
void Nybble(unsigned char dat)
{
    dat &= 0x0f;             //clear top bits of dat
    LCDdata &= 0xf0;         //clear bottom bits of port (interested only in DB7-DB4)
    LCDdata |= dat;          //or the two and store at port
    E = 1;
    Delay1TCY();             //enable pulse width >= 300ns (used 4uS)
    E = 0;                   //Clock enable: falling edge
}
 
/**********************************************************/
 
void init(void)
{
    LCDdata=0x00; 
    Delay1KTCYx(40);    //Wait >15 msec after power is applied (used 20mS)
    Nybble(0x3); 	//command 0x30 = Wake up
    Delay1KTCYx(15);     //must wait 160us, busy flag not available (used 160uS)
    Nybble(0x2); 	//command 0x30 = Wake up #2
    Delay1KTCYx(15); 	//must wait 160us, busy flag not available (used 160uS) 
 
    command(0x2C);      //Function set: 4-bit/2-line
    command(0xC);      //Set cursor
    command(0x06);      //Entry Mode set
    command(0x01);
}
/**********************************************************/
//End methods for LCD
/**********************************************************/

Ian Rogers · Sep 27, 2012

Tested in ISIS..... Runs good!!

xabi · Sep 27, 2012

erm..
is it something to do with the programming e.g. the delay?

Ian Rogers · Sep 28, 2012

No!! The software is good.. I didn't change anything. Looking at your hardware.... Have you a ground on the micro?

xabi · Sep 28, 2012

i connected the vss to mirco ground
it succeeded to show the hello world
but when i reset it, the words are blurred
after a few tries, it is blank

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HELP: Interfacing LCD with PIC18f4520 (MpLab C18 Compiler)

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