3 Wires LCD HEF4094B

Este esquema é totalmente baseado no da página http://www.arduino.cc/playground/Code/LCD3wires e bastante simples, desta forma 'poupamos' muitos pinos do Arduino, pois com apenas 3 pinos podemos controlar um LCD de 1 ou 2 linhas.

Utilizando o Shift Register HEF4094B temos o seguinte esquema:

A library está disponível em http://arduino.cc/playground/uploads/Code/LCD3WireLibrary.zip e podemos usar o exemplo que vem com a mesma:

// Example use of LCD3Wire library

// Almost a carbon-copy of LCD4BitExample.pde

#include <LCD3Wire.h> 

// Arduino pins

#define LCD_LINES 2  // number of lines in your display

#define DOUT_PIN  11  // Dout pin

#define STR_PIN   12  // Strobe pin

#define CLK_PIN   10  // Clock pin

#define LED_PIN   13 // we'll use the debug LED to output a heartbeat

//create object to control an LCD.  

LCD3Wire lcd = LCD3Wire(LCD_LINES, DOUT_PIN, STR_PIN, CLK_PIN); 

//some messages to display on the LCD

char msgs[6][15] = {"apple", "banana", "pineapple", "mango", "watermelon", "pear"};

int NUM_MSGS = 6;

void setup() { 

  lcd.init();

  //optionally, now set up our application-specific display settings, overriding whatever the lcd did in lcd.init()

  //lcd.commandWrite(0x0F);//cursor on, display on, blink on.  (nasty!)

  pinMode(LED_PIN, OUTPUT);  

}

void loop() {  

  digitalWrite(LED_PIN, HIGH);  //light the debug LED

  //pick a random message from the array

  int pick = random(NUM_MSGS);

  char* msg = msgs[pick];

  lcd.clear();

  lcd.printIn(msg);

  delay(1000);

  digitalWrite(LED_PIN, LOW);

  //print some dots individually

  for (int i=0; i<3; i++){

    lcd.print('.');

    delay(100);

  }

  //print something on the display's second line. 

  if(LCD_LINES>1){

    lcd.cursorTo(2, 0);  //line=2, x=0.

    lcd.printIn("Score: 6/7");

    delay(1000);

  }

  //scroll entire display 20 chars to left, delaying 50ms each inc

  lcd.leftScroll(20, 50);

}

Resultado:

Para termos suporte a LCDs 20x4:

Com a ajuda do fórum do Arduino (na página http://arduino.cc/forum/index.php/topic,10539.0.html), podemos facilmente adaptar a library para usarmos um LCD 20x4.

Basta alterar o método "cursorTo" na library para:

void LCD3Wire::cursorTo(int line_num, int x){

  //first, put cursor home

  commandWrite(CMD_HOME);

  //if we are on a 1-line display, set line_num to 1st line, regardless of given

  if (lcd_lines==1){

    line_num = 1;

  }

  //offset 40 chars in if second line requested

  if (line_num == 2){

    x += 40;

  }

// add the following code for 4 line display

  if (line_num == 3) {   // In fact, line 3 is an extension of the line 1 (beyond the 20 first characters)

    x += 20;

  }

  if (line_num == 4) {   // Line 4 is an extension of line 2

    x += 60;

  }

  //advance the cursor to the right according to position. (second line starts at position 40).

  for (int i=0; i<x; i++) {

    commandWrite(0x14);

  }

}

No exemplo podemos adaptar da seguinte forma:

// Example use of LCD3Wire library

// Almost a carbon-copy of LCD4BitExample.pde

#include <LCD3Wire.h> 

// Arduino pins

#define LCD_LINES 4  // number of lines in your display

#define DOUT_PIN  11  // Dout pin

#define STR_PIN   12  // Strobe pin

#define CLK_PIN   10  // Clock pin

#define LED_PIN   13 // we'll use the debug LED to output a heartbeat

//create object to control an LCD.  

LCD3Wire lcd = LCD3Wire(LCD_LINES, DOUT_PIN, STR_PIN, CLK_PIN); 

//some messages to display on the LCD

char msgs[6][15] = {"Arduino", "LCD 20X4", "Testing", "GrcByte", "Almamater", "LCD Test"};

int NUM_MSGS = 6;

void setup() { 

  lcd.init();

  //optionally, now set up our application-specific display settings, overriding whatever the lcd did in lcd.init()

  //lcd.commandWrite(0x0F);//cursor on, display on, blink on.  (nasty!)

  pinMode(LED_PIN, OUTPUT);  

}

void loop() {  

  digitalWrite(LED_PIN, HIGH);  //light the debug LED

  //pick a random message from the array

  int pick = random(NUM_MSGS);

  char* msg = msgs[pick];

  lcd.clear();

  lcd.printIn(msg);

  delay(1000);

  digitalWrite(LED_PIN, LOW);

  //print some dots individually

  for (int i=0; i<3; i++){

    lcd.print('.');

    delay(100);

  }

  //print something on the display's second line. 

  if(LCD_LINES==1){

    lcd.cursorTo(1, 0);  //line=2, x=0.

    lcd.printIn("Score: 6/7");

    delay(1000);

  }

    if(LCD_LINES==2){

    lcd.cursorTo(2, 0);  //line=2, x=0.

    lcd.printIn("Score: 6/7");

    delay(1000);

  }

   if(LCD_LINES==3){

    lcd.cursorTo(3, 0);  //line=2, x=0.

    lcd.printIn("Score: 6/7");

    delay(1000);

  }

  if(LCD_LINES==4){

    lcd.cursorTo(2, 0);  //line=2, x=0.

    lcd.printIn("Linha 2");

    delay(2000);

    lcd.cursorTo(3, 0);  //line=3, x=0.

    lcd.printIn("Linha 3");

    delay(2000);

    lcd.cursorTo(4, 0);  //line=4, x=0.

    lcd.printIn("Linha 4 - Yeahhhh!!");

    delay(2000);

  }

  //scroll entire display 20 chars to left, delaying 50ms each inc

  lcd.leftScroll(20, 50);

}

Download: Library Modificada

Resultado: