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LCD JHD162A interface wid pic 16F877

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sastraster

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I am using 16*2 LCD. I am using Hitech C compiler . I am trying to display some word. Sometimes it will display correctly sometimes it will not ..Sometimes some characters will be missing or it will display something else. I have tried to increase the delay.after each initialisation i am giving 5 sec as the delay just to cross check it. but even after tat i am facing the same problem. So kindly help me. I have attached the code also .


#include<htc.h>
#include<pic.h>
#define EN RC5 // 24
#define RS RC6 // 25
#define RW RC7 // 26
#define DB0 RB0
#define DB1 RB1
#define DB2 RB2
#define DB3 RB3
#define DB4 RB4
#define DB5 RB5
#define DB6 RB6
#define DB7 RB7
#define Data PORTB
char x;
#ifndef _XTAL_FREQ
#define _XTAL_FREQ 20000000
#endif
char count=0;


void init_LCD()
{
TRISB=0x00;
TRISC=0x00;
RS=0;
RW=0;
Data=0x38;
EN=1;
asm("nop");
EN=0;
for(i=1;i<1000;i++)
{ __delay_ms(5);
}
RS=0;
RW=0;
Data=0x0f;
EN=1;
asm("nop");
EN=0;
for(i=1;i<1000;i++)
{ __delay_ms(5);
}

RS=0;
RW=0;
Data=0x06;
EN=1;
asm("nop");
EN=0;
for(i=1;i<1000;i++)
{ __delay_ms(5);
}


RS=0;
RW=0;
Data=0x01;
EN=1;
asm("nop");
EN=0;
for(i=1;i<1000;i++)
{ __delay_ms(5);
}

}


void display(char x)
{ RW=0;
RS=1;
Data=x;
EN=1;
asm("nop");
EN=0;
for(i=1;i<1000;i++)
{ __delay_ms(5);
}
}

void LCD_sendstring(unsigned char *var)
{
while(*var) //till string ends
display(*var++); //send characters one by one
}

void main()
{
unsigned char msg1[] ="Traffic Density";
for(int i=1;i<50;i++)
{
__delay_ms(1);
}

init_LCD();
RC0=~RC0;
LCD_sendstring(msg1);
while(1)
{
}

}
 

BGAman

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Hi,
what frequency you are running your PIC? From datasheet minimum pulse width for EN is 230ns or 450ns and data setup 80ns or 195 ns, so your EN = 1; asm("nop"); EN = 0; is not enough!
Minimum E cycle frequency is 1ms, so __delay_ms(1) between commands is enough. I also recommend place one NOP between RS and/or RW changes and E rising edge.
Your control signals on scope should be as pictures on page 4 of datasheet.
Regards
Pavel.
 

kandhu26

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This is the proper initialization of LCD As per datasheet... But many people are not following this initialization... So can you try with this initialization.. I also sometime faced this kind of problem due to unproper initialization... But i am sure this is the problem... but you could try this one...
STEP1: Write Function set [0x38] into Command Register.. [8 bit interfacing, Multiple Line, 5x7 font size]
STEP2: Give 4ms delay
STEP3: Same Step 1
STEP4: Give 1ms delay
STEP5: Same Step 1
STEP6: Write the cursor/display shift [0x1C] into Command Register with delay... [Shift Entire display into right]
STEP7: Write Display ON/OFF control [0x0C] into Command Register with Delay... [No cursor and No blink]
STEP8: Write Entry mode set [0x06] into Command Register with Delay... [Increment without shift]
STEP9: Write Home cursor [0x02] into command register with Delay...[Home cursor]
STEP10: Write Clear display [0x01] into command register with delay... [Clear Display]
 

qwertyuiop415263

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use capacitor(of any value) with your power supply. i think your power supply is not well regulated.
 

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