How to display variables in LCD using PIC18 and XC8 compiler

Question

I am trying to display a variable in an LCD. I am using a PIC18F4550 and I am compiling with XC8. My code is the next:

#include<pic18f4550.h> //----Include Reg file of Pic18f4550
#define lcd PORTD //----Assing PORTD as lcd
#define rs PORTCbits.RC0 //----Register Select Pin for Control of LCD
#define rw PORTCbits.RC1 //----Read/Write Pin for Control of LCD
#define en PORTCbits.RC2 //----Enable Pin for Control of LCD
#include "lcd.h";
#include "stdlib.h";
//////////// Main Program //////////////////////////////////////////////////////
void main()
{
 DDRD = 0x00; //----Set as output
 DDRC = 0x00; //----Set as output
 lcd_init(); //----Initialize LCd
 char k = "p";
 while(1) //-----Creating Super Loop
 {
 lcd_cmd(0x80); //----- First row in LCD
 lcd_msg("LCD Display"); //-----Data
 lcd_cmd(0xC0); //-----Last lacation of 1st Line
 lcd_msg("Variable:");
 lcd_msg(k);
 delay(250); //-----250 msec delay
 }
}

and I am using the next lcd.h header:

////// Proto-Type Decleration //////////////////////////////////////////////////
void lcd_cmd(unsigned char x); //----Function to Send Command to LCD
void lcd_dwr(unsigned char x); //----Function to Send Data to LCD
void lcd_msg(unsigned char *c); //----Function to Send String of Data to LCD
void lcd_lat(); //----Function to Latch data into LCD
void lcd_ready(); //----Function to Check LCD is Busy
void lcd_init(); //----Initialization of LCD
void delay(unsigned int ms); //----Delay Function for 1ms
////////////////////////////////////////////////////////////////////////////////
void lcd_cmd(unsigned char x)
{
 lcd_ready(); //----To Check whether lcd is busy
 lcd = x; //----8-Bit Command is Send to PORTD
 rs = 0; //----Register Select Pin is Low => Command Register
 rw = 0; //----Read/Write Pin is Low => Write.
 lcd_lat(); //----Latch data into LCD
}
void lcd_dwr(unsigned char x)
{
 lcd_ready(); //----To Check whether lcd is busy
 lcd = x; //----8-Bit Data is Send to PORTD
 rs = 1; //----Register Select Pin is High => Data Register
 rw = 0; //----Read/Write Pin is Low => Write.
 lcd_lat(); //----Latch data into LCD
}
void lcd_msg(unsigned char *c)
{
 while(*c != 0) //---Check till last data is send
 lcd_dwr(*c++); //---Send data to lcd and increment
}
void lcd_lat() //----To Latch data into LCD
{
 en = 1; //----Enable Pin goes high
 delay(1); //----delay of 1ms
 en = 0; //----Enable Pin goes Low
}
void lcd_ready()
{
 lcd = 0xFF; //----PORTD is High
 lcd &= 0x80; //----D7 is set as high
 rs = 0; //----Command Register is Selected
 rw = 1; //----Read/Write Pin is High => Read
 en = 0; delay(1); en = 1; //----Low to High to read data from LCD
 if(lcd == 0x80)
 {
 en = 0; delay(1); en = 1; //----Low to High to read data from LCD
 }
 else
 {
 //---Do nothing.
 }
}
void lcd_init()
{
 lcd_cmd(0x38); //----8-bit data and 16x2 line
 lcd_cmd(0x0E); //----Cusor Blinking
 lcd_cmd(0x01); //----Clear LCD
 lcd_cmd(0x06); //----Increment Cusor
 lcd_cmd(0x80); //----1st low of 1st row
}
void delay(unsigned int ms)
{
 unsigned int i,j;
 for(i=0;i<=120;i++) //---To generate 1ms delay
 for(j=0;j<=ms;j++); //---To generate user define delay
}

But I am not capable to display the character "p" enter image description here

I am new on pics. I would appreciate any suggestions, thanks

• DigitalNinja: Are the other parts of your LCD code working? Is it just the variable that isn't being displayed? If so, is it displaying anything for the variable? A char is just a single character, so you should assign it like this char k = 'p';, using single quotes. Double quotes are for strings.
• Nau: Yes, the other parts are working, I can even create and display special characters. I tried to use single quotes too. But I obtain the same result as the image I uploaded
• DigitalNinja: It looks like lcd_msgwants a char*. If you want to display a single character try using lcd_dwr instead. So keep char k = 'p'; (single quotes), and call lcd_dwr(k); instead of lcd_msg(k);.

Answer 1

The problem is that the lcd_msg() routine wants a char *, but you're passing it a single char instead. You could either turn your variable into a NUL terminated string like this:

char *k = "p";
// other code
lcd_msg(k);

Or you could display a single character like so:

char k = 'p'; // note use of single quotes for single char
// other code
lcd_dwr(k);