[SOLVED] 16X4 Lcd displaying unreadable characters with Pic18f4550

Praveen Kumar P S · Aug 21, 2014

Hey GUYS........
I'm new to pic programming and to this forum. I'm trying to program a pic18f4550 which receives data from virtual terminal(isis) and display it on a 16x4 lcd display....But it displays unreadable characters like α α α α

My Compiler:: CCS C Compiler 5.015
HERE is my prgm:

Code:

#include <18f4550.h> 
#fuses HSPLL,NOWDT,NOPROTECT,NOLVP,NODEBUG,USBDIV,PLL5,CPUDIV1,VREGEN,NOPBADEN 
#use delay(clock=48000000) 
#use rs232(baud=56000, xmit=PIN_C6,parity=N,rcv=PIN_C7,ERRORS,bits=8)            
#include <flex_lcd416.c> 
void main()                                        
{ 
for(;;) 
  { 
    lcd_init();                  
    lcd_setcursor_vb(1,1);    
    lcd_putc("Receving Data\n"); 
    delay_ms(1000);                                                                        
  
    if(kbhit()) 
    {    
    lcd_putc(getc());  
    output_high(PIN_A0); 
    delay_ms(500); 
    }                                
    else                                                        
    {                  
    output_low(PIN_A0); 
    delay_ms(100); 
    } 
} 
                                            
}

Here is my LCD Driver:

Code:

             // flex_lcd.c 

// These pins are for the Microchip PicDem2-Plus board, 
// which is what I used to test the driver.  Change these 
// pins to fit your own board. 

#define LCD_DB4   PIN_B4                                    
#define LCD_DB5   PIN_B5 
#define LCD_DB6   PIN_B6 
#define LCD_DB7   PIN_B7 
#define LCD_RS    PIN_C0 
#define LCD_RW    PIN_C1                        
#define LCD_E     PIN_C2 
                                                  
// If you only want a 6-pin interface to your LCD, then 
// connect the R/W pin on the LCD to ground, and comment 
// out the following line. 

#define USE_LCD_RW   1 

//======================================== 

#define lcd_type 2        // 0=5x7, 1=5x10, 2=2 lines 
#define lcd_line_two 0x40 // LCD RAM address for the 2nd line 


int8 const LCD_INIT_STRING[4] = 
{ 
 0x20 | (lcd_type << 2), // Func set: 4-bit, 2 lines, 5x8 dots 
 0xc,                    // Display on 
 1,                      // Clear display 
 6                       // Increment cursor 
 }; 


//------------------------------------- 
void lcd_send_nibble(int8 nibble) 
{ 
// Note:  !! converts an integer expression 
// to a boolean (1 or 0). 
 output_bit(LCD_DB4, !!(nibble & 1)); 
 output_bit(LCD_DB5, !!(nibble & 2)); 
 output_bit(LCD_DB6, !!(nibble & 4)); 
 output_bit(LCD_DB7, !!(nibble & 8)); 

 delay_cycles(1); 
 output_high(LCD_E); 
 delay_us(2); 
 output_low(LCD_E); 
} 

//----------------------------------- 
// This sub-routine is only called by lcd_read_byte(). 
// It's not a stand-alone routine.  For example, the 
// R/W signal is set high by lcd_read_byte() before 
// this routine is called. 

#ifdef USE_LCD_RW 
int8 lcd_read_nibble(void) 
{ 
int8 retval; 
// Create bit variables so that we can easily set 
// individual bits in the retval variable. 
#bit retval_0 = retval.0 
#bit retval_1 = retval.1 
#bit retval_2 = retval.2 
#bit retval_3 = retval.3 

retval = 0; 

output_high(LCD_E); 
delay_cycles(1); 

retval_0 = input(LCD_DB4); 
retval_1 = input(LCD_DB5); 
retval_2 = input(LCD_DB6); 
retval_3 = input(LCD_DB7); 

output_low(LCD_E); 

return(retval); 
} 
#endif 

//--------------------------------------- 
// Read a byte from the LCD and return it. 

#ifdef USE_LCD_RW 
int8 lcd_read_byte(void) 
{ 
int8 low; 
int8 high; 

output_high(LCD_RW); 
delay_cycles(1); 

high = lcd_read_nibble(); 

low = lcd_read_nibble(); 

return( (high<<4) | low); 
} 
#endif 

//---------------------------------------- 
// Send a byte to the LCD. 
void lcd_send_byte(int8 address, int8 n) 
{ 
output_low(LCD_RS); 

#ifdef USE_LCD_RW 
while(bit_test(lcd_read_byte(),7)) ; 
#else 
delay_us(60); 
#endif 

if(address) 
   output_high(LCD_RS); 
else 
   output_low(LCD_RS); 

 delay_cycles(1); 

#ifdef USE_LCD_RW 
output_low(LCD_RW); 
delay_cycles(1); 
#endif 

output_low(LCD_E); 

lcd_send_nibble(n >> 4); 
lcd_send_nibble(n & 0xf); 
} 

//---------------------------- 
void lcd_init(void) 
{ 
int8 i; 

output_low(LCD_RS); 

#ifdef USE_LCD_RW 
output_low(LCD_RW); 
#endif 

output_low(LCD_E); 

delay_ms(15); 

for(i=0 ;i < 3; i++) 
   { 
    lcd_send_nibble(0x03); 
    delay_ms(5); 
   } 

lcd_send_nibble(0x02); 

for(i=0; i < sizeof(LCD_INIT_STRING); i++) 
   { 
    lcd_send_byte(0, LCD_INIT_STRING[i]); 

    // If the R/W signal is not used, then 
    // the busy bit can't be polled.  One of 
    // the init commands takes longer than 
    // the hard-coded delay of 60 us, so in 
    // that case, lets just do a 5 ms delay 
    // after all four of them. 
    #ifndef USE_LCD_RW 
    delay_ms(5); 
    #endif 
   } 

} 

//---------------------------- 

void lcd_gotoxy(int8 x, int8 y) 
{ 
int8 address; 

if(y != 1) 
   address = lcd_line_two; 
else 
   address=0; 

address += x-1; 
lcd_send_byte(0, 0x80 | address); 
} 

//----------------------------- 
void lcd_putc(char c) 
{ 
 switch(c) 
   { 
    case '\f': 
      lcd_send_byte(0,1); 
      delay_ms(2); 
      break; 

    case '\n': 
       lcd_gotoxy(1,2); 
       break; 

    case '\b': 
       lcd_send_byte(0,0x10); 
       break; 

    default: 
       lcd_send_byte(1,c); 
       break; 
   } 
} 

//------------------------------ 
#ifdef USE_LCD_RW 
char lcd_getc(int8 x, int8 y) 
{ 
char value; 

lcd_gotoxy(x,y); 

// Wait until busy flag is low. 
while(bit_test(lcd_read_byte(),7)); 

output_high(LCD_RS); 
value = lcd_read_byte(); 
output_low(lcd_RS); 

return(value); 
} 
#endif 

void lcd_setcursor_vb(short visible, short blink) { 
  lcd_send_byte(0, 0xC|(visible<<1)|blink); 
}

here is the output:

plzzz help me guys..............:bang::bang::bang::bang:

Raady Here · Aug 21, 2014

lcd_putc("Receving Data\n")
change to
lcd_putc("Receving Data")

paulfjujo · Aug 21, 2014

hello,

lcd_putc write a caractere not a string..
use lcd_put_text(...
or similar function

if you have not this kind of function, write one like this

Code:

char s[21]; // table to store a string  // in Ram


void Lcd_Put_String(char * t)
{
char * p;
p=t;   // use p pointer to don't modify the  original t pointer
while(*p>0)
{
lcd_putc(*p):
p++;
}


... in main program
lcd_setcursor_vb(1,1);  // set cursor on the right place
strcyprgm2ram(s,"Receveiving Data);                             // function to transfer ROM string to RAM string
Lcd_Put_String(s);   //

Praveen Kumar P S · Aug 21, 2014

Raady Here said:
lcd_putc("Receving Data\n")
change to
lcd_putc("Receving Data")

First of thnk u very much for that quick replay....:-D

I tried it....but still the same.....:bang::bang::bang::bang::bang:

Is their any thing wrong in the program....???:roll:

Thank u......

Raady Here · Aug 22, 2014

paulfjujo was right !
i didnt go through your program much yesterday, switch case you are using the function lcd_puts doesnt work. comparision neither a string nor a ascii.

Praveen Kumar P S · Aug 22, 2014

Raady Here said:
paulfjujo was right !
i didnt go through your program much yesterday, switch case you are using the function lcd_puts doesnt work. comparision neither a string nor a ascii.

I change my lcd driver to the below one.....

Code:

    // Flex_LCD416.c 

// These pins are for my Microchip PicDem2-Plus board, 
// which I used to test this driver. 
// An external 20x4 LCD is connected to these pins. 
// Change these pins to match your own board's connections. 

#define LCD_DB4   PIN_B4 
#define LCD_DB5   PIN_B5 
#define LCD_DB6   PIN_B6 
#define LCD_DB7   PIN_B7 

#define LCD_RS    PIN_C4 
#define LCD_RW    PIN_C5 
#define LCD_E     PIN_C6 

/* 
// To prove that the driver can be used with random 
// pins, I also tested it with these pins: 
#define LCD_DB4   PIN_D4 
#define LCD_DB5   PIN_B1 
#define LCD_DB6   PIN_C5                    
#define LCD_DB7   PIN_B5 

#define LCD_RS    PIN_E2 
#define LCD_RW    PIN_B2 
#define LCD_E     PIN_D6 
*/ 

// If you want only a 6-pin interface to your LCD, then 
// connect the R/W pin on the LCD to ground, and comment 
// out the following line.  Doing so will save one PIC 
// pin, but at the cost of losing the ability to read from 
// the LCD.  It also makes the write time a little longer 
// because a static delay must be used, instead of polling 
// the LCD's busy bit.  Normally a 6-pin interface is only 
// used if you are running out of PIC pins, and you need 
// to use as few as possible for the LCD. 
#define USE_RW_PIN   1      


// These are the line addresses for most 4x20 LCDs. 
#define LCD_LINE_1_ADDRESS 0x00 
#define LCD_LINE_2_ADDRESS 0x40 
#define LCD_LINE_3_ADDRESS 0x10 
#define LCD_LINE_4_ADDRESS 0x50 

// These are the line addresses for LCD's which use 
// the Hitachi HD66712U controller chip. 
/* 
#define LCD_LINE_1_ADDRESS 0x00 
#define LCD_LINE_2_ADDRESS 0x20 
#define LCD_LINE_3_ADDRESS 0x40 
#define LCD_LINE_4_ADDRESS 0x60 
*/ 


//======================================== 

#define lcd_type 2   // 0=5x7, 1=5x10, 2=2 lines(or more) 

int8 lcd_line; 

int8 const LCD_INIT_STRING[4] = 
{ 
 0x20 | (lcd_type << 2),  // Set mode: 4-bit, 2+ lines, 5x8 dots 
 0xc,                     // Display on 
 1,                       // Clear display 
 6                        // Increment cursor 
 }; 


//------------------------------------- 
void lcd_send_nibble(int8 nibble) 
{ 
// Note:  !! converts an integer expression 
// to a boolean (1 or 0). 
 output_bit(LCD_DB4, !!(nibble & 1)); 
 output_bit(LCD_DB5, !!(nibble & 2)); 
 output_bit(LCD_DB6, !!(nibble & 4));    
 output_bit(LCD_DB7, !!(nibble & 8));    

 delay_cycles(1); 
 output_high(LCD_E); 
 delay_us(2); 
 output_low(LCD_E); 
} 

//----------------------------------- 
// This sub-routine is only called by lcd_read_byte(). 
// It's not a stand-alone routine.  For example, the 
// R/W signal is set high by lcd_read_byte() before 
// this routine is called.      

#ifdef USE_RW_PIN 
int8 lcd_read_nibble(void) 
{ 
int8 retval; 
// Create bit variables so that we can easily set 
// individual bits in the retval variable. 
#bit retval_0 = retval.0 
#bit retval_1 = retval.1 
#bit retval_2 = retval.2 
#bit retval_3 = retval.3 

retval = 0; 
    
output_high(LCD_E); 
delay_us(1); 

retval_0 = input(LCD_DB4); 
retval_1 = input(LCD_DB5); 
retval_2 = input(LCD_DB6); 
retval_3 = input(LCD_DB7); 
  
output_low(LCD_E); 
delay_us(1); 
    
return(retval);    
}    
#endif 

//--------------------------------------- 
// Read a byte from the LCD and return it. 

#ifdef USE_RW_PIN 
int8 lcd_read_byte(void) 
{ 
int8 low; 
int8 high; 

output_high(LCD_RW); 
delay_cycles(1); 

high = lcd_read_nibble(); 

low = lcd_read_nibble(); 

return( (high<<4) | low); 
} 
#endif 

//---------------------------------------- 
// Send a byte to the LCD. 
void lcd_send_byte(int8 address, int8 n) 
{ 
output_low(LCD_RS); 

#ifdef USE_RW_PIN 
while(bit_test(lcd_read_byte(),7)) ; 
#else 
delay_us(60); 
#endif 

if(address) 
   output_high(LCD_RS); 
else 
   output_low(LCD_RS); 
      
 delay_cycles(1); 

#ifdef USE_RW_PIN 
output_low(LCD_RW); 
delay_cycles(1); 
#endif 

output_low(LCD_E); 

lcd_send_nibble(n >> 4); 
lcd_send_nibble(n & 0xf); 
} 
//---------------------------- 

void lcd_init(void) 
{ 
int8 i; 

lcd_line = 1; 

output_low(LCD_RS); 

#ifdef USE_RW_PIN 
output_low(LCD_RW); 
#endif 

output_low(LCD_E); 

// Some LCDs require 15 ms minimum delay after 
// power-up.  Others require 30 ms.  I'm going 
// to set it to 35 ms, so it should work with 
// all of them. 
delay_ms(35);          

for(i=0 ;i < 3; i++) 
   { 
    lcd_send_nibble(0x03); 
    delay_ms(5); 
   } 

lcd_send_nibble(0x02); 

for(i=0; i < sizeof(LCD_INIT_STRING); i++) 
   { 
    lcd_send_byte(0, LCD_INIT_STRING[i]); 

    // If the R/W signal is not used, then 
    // the busy bit can't be polled.  One of 
    // the init commands takes longer than 
    // the hard-coded delay of 50 us, so in 
    // that case, lets just do a 5 ms delay 
    // after all four of them. 
    #ifndef USE_RW_PIN 
    delay_ms(5); 
    #endif 
   } 

} 

//---------------------------- 

void lcd_gotoxy(int8 x, int8 y) 
{ 
int8 address; 


switch(y) 
  { 
   case 1: 
     address = LCD_LINE_1_ADDRESS; 
     break; 

   case 2: 
     address = LCD_LINE_2_ADDRESS; 
     break; 

   case 3: 
     address = LCD_LINE_3_ADDRESS; 
     break; 

   case 4: 
     address = LCD_LINE_4_ADDRESS; 
     break; 

   default: 
     address = LCD_LINE_1_ADDRESS; 
     break; 
      
  } 

address += x-1; 
lcd_send_byte(0, 0x80 | address); 
} 

//----------------------------- 
void lcd_putc(char c) 
{ 
 switch(c) 
   { 
    case '\f': 
      lcd_send_byte(0,1); 
      lcd_line = 1; 
      delay_ms(2); 
      break; 
    
    case '\n': 
       lcd_gotoxy(1, ++lcd_line); 
       break; 
    
    case '\b': 
       lcd_send_byte(0,0x10); 
       break; 
    
    default: 
       lcd_send_byte(1,c); 
       break; 
   } 
} 

//------------------------------ 
#ifdef USE_RW_PIN 
char lcd_getc(int8 x, int8 y) 
{ 
char value; 

lcd_gotoxy(x,y); 

// Wait until busy flag is low. 
while(bit_test(lcd_read_byte(),7)); 

output_high(LCD_RS); 
value = lcd_read_byte(); 
output_low(LCD_RS); 

return(value); 
} 
#endif 

void lcd_setcursor_vb(short visible, short blink) { 
  lcd_send_byte(0, 0xC|(visible<<1)|blink); 
}

now lcd works perfectly....But it not works when following staments are used in the main program....

Code:

1) #use rs232(baud=56000, xmit=PIN_C6,parity=N,rcv=PIN_C7,ERRORS,bits=8) 

2) getc();

Any Ideaaa.....Guys:fight::fight::fight:

paulfjujo · Aug 22, 2014

hello,

I didn't check all your LCD program
but if you are using RC5 bit, i suspect a probleme with PORT C, wich is concern by UART (RC7 Rx and RC6 Tx)...
try to use another bit ,not in PORT C for DB6..

to change only one bit in a port, it needs to use :
Read the PORT, then apply AND and OR function to change only one bit
without affecting other bits.

Praveen Kumar P S · Aug 22, 2014

paulfjujo said:
hello,

I didn't check all your LCD program
but if you are using RC5 bit, i suspect a probleme with PORT C, wich is concern by UART (RC7 Rx and RC6 Tx)...
try to use another bit ,not in PORT C for DB6..

to change only one bit in a port, it needs to use :
Read the PORT, then apply AND and OR function to change only one bit
without affecting other bits.

I changed my lcd from port C to Port B now my Lcd works fine......:-D
Could u please tell me how to enable serial communication with pin C6 and C7. Is Serial communication possible with other ports????:thinker:

Praveen Kumar P S · Aug 22, 2014

Hey Guys Finally it worked ....................
I removed my lcd from port C to Port D and removed UART1 from #use 232() and it worked sucessfully..........
thanks to all guys who helped me and a special thanks to...paulfjujo....

Here is my final program::

Code:

#include <18f4550.h> 
#fuses HSPLL,NOWDT,NOPROTECT,NOLVP,NODEBUG,USBDIV,PLL5,CPUDIV1,VREGEN,NOPBADEN,BORV45,PUT
#use delay(clock=48000000)
#use rs232(baud=9600,xmit=PIN_C6,parity=N,rcv=PIN_C7,ERRORS,bits=8)
#include <flex_lcd416.c>
#include <kbd.c>

void main()
{
int p;
 lcd_init();                  
 lcd_setcursor_vb(1,1);    
 lcd_putc("Receving Data\n");                      
 delay_ms(1000); 
 for(;;)
 {  
     output_high(PIN_A0);
     p=getc();
     lcd_putc(p);
     delay_ms(100);
     printf("Data Send");
     delay_ms(100);
     } 
  }

THANK YOU............:-D:-D

[SOLVED] 16X4 Lcd displaying unreadable characters with Pic18f4550

Praveen Kumar P S

Member level 4

Raady Here

Full Member level 5

Praveen Kumar P S

paulfjujo

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Praveen Kumar P S

Praveen Kumar P S

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Raady Here

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Praveen Kumar P S

Praveen Kumar P S

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paulfjujo

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Praveen Kumar P S

Praveen Kumar P S

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Praveen Kumar P S

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