Reference for a very cheap (3.99 € with free shipping) LCD keypad shield for Arduino bought from banggood (SKU: SKU083549).
Here goes the source code (adapted from this source, slightly improved with custom functions to switch light when pushing the Select button):
//Sample using LiquidCrystal library
#include <LiquidCrystal.h>
/*******************************************************
This program will test the LCD panel and the buttons
Mark Bramwell, July 2010
********************************************************/
// select the pins used on the LCD panel
LiquidCrystal lcd(8, 9, 4, 5, 6, 7);
// define some values used by the panel and buttons
int lcd_key = 0;
int adc_key_in = 0;
#define btnRIGHT 0
#define btnUP 1
#define btnDOWN 2
#define btnLEFT 3
#define btnSELECT 4
#define btnNONE 5
// read the buttons
int read_LCD_buttons()
{
adc_key_in = analogRead(0); // read the value from the sensor
// my buttons when read are centered at these values: 0, 144, 329, 504, 741
// we add approx 50 to those values and check to see if we are close
if (adc_key_in > 1000) return btnNONE; // We make this the 1st option for speed reasons since it will be the most likely result
// For V1.1 use this threshold
/* if (adc_key_in < 50) return btnRIGHT;
if (adc_key_in < 250) return btnUP;
if (adc_key_in < 450) return btnDOWN;
if (adc_key_in < 650) return btnLEFT;
if (adc_key_in < 850) return btnSELECT;
*/
// For V1.0 comment the other threshold and use the one below:
if (adc_key_in < 50) return btnRIGHT;
if (adc_key_in < 195) return btnUP;
if (adc_key_in < 380) return btnDOWN;
if (adc_key_in < 555) return btnLEFT;
if (adc_key_in < 790) return btnSELECT;
return btnNONE; // when all others fail, return this...
}
#define LCDbacklight() pinMode(10, INPUT) // turn on backlight
#define LCDnoBacklight() pinMode(10, OUTPUT) // turn off backlight
int lightUp = 1;
int previousBtn = -1;
int switchLight()
{
if(lightUp)
{
LCDnoBacklight();
}
else
{
LCDbacklight();
}
lightUp=(++lightUp)%2;
return 0;
}
void setup()
{
LCDbacklight();
digitalWrite(10,LOW); // when D10 is set to high it burns the arduino and shield, see http://forum.arduino.cc/index.php?topic=96747.msg725979#msg725979
lcd.begin(16, 2); // start the library
lcd.setCursor(0,0);
lcd.print("Push the buttons"); // print a simple message
}
void loop()
{
lcd.setCursor(9,1); // move cursor to second line "1" and 9 spaces over
lcd.print(millis()/1000); // display seconds elapsed since power-up
lcd.setCursor(0,1); // move to the begining of the second line
lcd_key = read_LCD_buttons(); // read the buttons
if(lcd_key == btnSELECT && previousBtn != btnSELECT)
{
switchLight();
}
previousBtn = lcd_key;
switch (lcd_key) // depending on which button was pushed, we perform an action
{
case btnRIGHT:
{
lcd.print("RIGHT ");
break;
}
case btnLEFT:
{
lcd.print("LEFT ");
break;
}
case btnUP:
{
lcd.print("UP ");
break;
}
case btnDOWN:
{
lcd.print("DOWN ");
break;
}
case btnSELECT:
{
lcd.print("SELECT");
break;
}
case btnNONE:
{
lcd.print("NONE ");
break;
}
}
}
And now animations! (with serial debugging example) WIP!
//Sample using LiquidCrystal library
#include <LiquidCrystal.h>
/*******************************************************
This program will show some animations on your LCD screen
Based on Mark Bramwell version, July 2010 http://www.dfrobot.com/wiki/index.php?title=Arduino_LCD_KeyPad_Shield_%28SKU:_DFR0009%29#Example_use_of_LiquidCrystal_library
********************************************************/
// select the pins used on the LCD panel
LiquidCrystal lcd(8, 9, 4, 5, 6, 7);
// define some values used by the panel and buttons
byte lcd_key = 0;
int adc_key_in = 0;
#define btnRIGHT 0
#define btnUP 1
#define btnDOWN 2
#define btnLEFT 3
#define btnSELECT 4
#define btnNONE 5
// read the buttons
byte read_LCD_buttons()
{
adc_key_in = analogRead(0); // read the value from the sensor
// my buttons when read are centered at these valies: 0, 144, 329, 504, 741
// we add approx 50 to those values and check to see if we are close
if (adc_key_in > 1000) return btnNONE; // We make this the 1st option for speed reasons since it will be the most likely result
// For V1.0 comment the other threshold and use the one below:
if (adc_key_in < 50) return btnRIGHT;
if (adc_key_in < 195) return btnUP;
if (adc_key_in < 380) return btnDOWN;
if (adc_key_in < 555) return btnLEFT;
if (adc_key_in < 790) return btnSELECT;
return btnNONE; // when all others fail, return this...
}
#define LCDbacklight() pinMode(10, INPUT) // turn on backlight
#define LCDnoBacklight() pinMode(10, OUTPUT) // turn off backlight
boolean lightUp = true;
byte previousBtn = -1;
byte menu = 0;
byte menusNumber = 2;
void switchLight()
{
if(lightUp)
{
LCDnoBacklight();
}
else
{
LCDbacklight();
}
lightUp=!lightUp;
return;
}
byte X = 0;
byte Y = 0;
byte sizeX = 16;
byte sizeY = 2;
void chenillard()
{
lcd.setCursor(X,Y);
lcd.write(254); // clear char where cursor is
if(Y == 0 && X <= sizeX)
{
X++;
}
if(X == sizeX && Y <= sizeY-1)
{
Y++;
}
if(X == 0 && Y > 0)
{
Y--;
}
else
{
if(Y == sizeY-1 && X >= 0)
{
X--;
}
}
lcd.setCursor(X,Y);
lcd.write(255);
}
void randomStars()
{
lcd.setCursor(X,Y);
lcd.write(254);
X=random(0, sizeX);
Y=random(0, sizeY);
lcd.setCursor(X,Y);
lcd.write('*');
}
void setup()
{
digitalWrite(10,LOW); // when D10 is set to high it burns the arduino and shield, see http://forum.arduino.cc/index.php?topic=96747.msg725979#msg725979
lcd.begin(sizeX, sizeY); // start the library
lcd.setCursor(0,0);
lcd.print("Push up and down buttons"); // print a simple message
delay(500);
lcd.clear();
randomSeed(analogRead(10));
Serial.begin(9600);
}
void loop()
{
lcd_key = read_LCD_buttons(); // read the buttons
if(previousBtn != lcd_key)
{
//lcd.setCursor(9,1); // move cursor to second line "1" and 9 spaces over
//lcd.print(millis()/1000); // display seconds elapsed since power-up
//lcd.setCursor(0,1); // move to the begining of the second line
switch (lcd_key) // depending on which button was pushed, we perform an action
{
X=0;Y=0;
case btnRIGHT:
{
//lcd.print("RIGHT ");
break;
}
case btnLEFT:
{
//lcd.print("LEFT ");
break;
}
case btnUP:
{
lcd.clear();
menu=(++menu)%menusNumber;
break;
}
case btnDOWN:
{
lcd.clear();
menu=(--menu)%menusNumber;
break;
}
case btnSELECT:
{
switchLight();
break;
}
case btnNONE:
{
break;
}
}
}
switch(menu)
{
case 0:
{
randomStars();
break;
}
case 1:
{
chenillard();
break;
}
}
previousBtn = lcd_key;
/*Serial.print('X=');*/Serial.println(X);
/*Serial.print('Y=');*/Serial.println(Y);
delay(200);
}