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Circuit Description

This applet demonstrates a PIC16-based controller for a LC Display and shows how to create custom symbols via the user-writeable character-generator functions. The circuit consists of the microcontroller and a standard ASCII-mode liquid-crystal display..

Open the PIC user-interface to watch the program execution, setting breakpoints, etc. (I recommend to uncheck the 'update display' checkbox and to click the data and program memories to enforce repainting. This saves a lot of CPU cycles and makes the animation go smoothly).

The LC display show a simple animantion based on two new chacracter. The C source code has been written by Ricardo Ferreira to teach embedded systme during the Computer Organization Undergraduate Course, Universidade Federal de Viçosa, Brazil.

The following C code shows how you could create new characters via the built-in user-writeable character-generator of the LCD. You can also download an archive file (.tar.gz) with the source code and include files.

// usr/hitech/bin/picl -16f84 -C -Zg gerandocaracter2.c lcd.c delay.c
// usr/hitech/bin/picl -16f84 -Ogerandocaracter2.hex \
//                                gerandocaracter2.obj lcd.obj delay.obj

#include	
#include	"lcd.h"
#include	"delay.h"



void SendNumbertoLCD(char n)
{
    char c;
    c = (char)((n/10)+48); // Dezena
    lcd_putch(c);
    c = (char)((n%10)+48); // Unidade
    lcd_putch(c);
}

void Wait()
{
	DelayMs(50);

}

main(){



  TRISA = 0x00; // Output bits porta, xxxRE
  TRISB = 0x00; // Output bits portb 7654xxxx


  lcd_init();
  lcd_puts("DPI.....");

  /* create a new caracter
    address 0x40 (you can use 48,50,58,...,78
    to use: select 0x00  (you can use 01,...07)
    matrix 5x7

	set position 40
	write 8 words (caracter definition)

  */
  lcd_write(0x40);  // set 40
  lcd_putch(0x04);  // first line 00100
  lcd_putch(0x0A);  //            01010
  lcd_putch(0x04);  //            00100
  lcd_putch(0x1F);  //            11111
  lcd_putch(0x04);  //            00100
  lcd_putch(0x0A);  //            01010
  lcd_putch(0x11);  //            10001
  lcd_putch(0x00);  //            00000

  lcd_write(0x48);  // set 48
  lcd_putch(0x04);  // first line 00100
  lcd_putch(0x1B);  //            11011
  lcd_putch(0x15);  //            10101
  lcd_putch(0x0e);  //            01110
  lcd_putch(0x04);  //            00100
  lcd_putch(0x0A);  //            01010
  lcd_putch(0x0A); //             01010
  lcd_putch(0x00);  //            00000



  while(1){
// goto to colunm 5
  lcd_goto(5);
  // write the  caracter.0..
  lcd_putch(0x00);
  Wait();
// goto to colunm 5
  lcd_goto(5);
  // write the  caracter.1..
  lcd_putch(0x01);
  Wait();


    }
}