LCD.cpp

/*
 * Copyright (C) 2012 Southern Storm Software, Pty Ltd.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included
 * in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 */

#include "LCD.h"
#include <avr/pgmspace.h>
#if defined(ARDUINO) && ARDUINO >= 100
#include <Arduino.h>
#else
#include <WProgram.h>
#endif

#define LCD_BACK_LIGHT          3        // Default LCD backlight is on D3
#define LCD_BUTTON_PIN          A0       // Button state is on A0

#define DEBOUNCE_DELAY          10      // Delay in ms to debounce buttons

void LCD::init()
{
    // The Freetronics display is 16x2.
    begin(16, 2);

    // Configure the backlight pin, but don't activate it yet in
    // case the application sets it to something else during setup().
    // Initialization will be forced in the first call to getButton().
    _backlightPin = LCD_BACK_LIGHT;
    backlightInit = false;

    // Initialise button input.
    pinMode(LCD_BUTTON_PIN, INPUT);
    digitalWrite(LCD_BUTTON_PIN, LOW);
    prevButton = LCD_BUTTON_NONE;
    debounceButton = LCD_BUTTON_NONE;
    lastDebounce = 0;
    eatRelease = false;

    // Initialize screen saver.
    timeout = 0;
    lastRestore = millis();
    screenSaved = false;
    mode = DisplayOff;
}

void LCD::setBacklightPin(uint8_t pin)
{
    if (_backlightPin != pin) {
        if (backlightInit) {
            // Restore the previous backlight pin to input, floating.
            pinMode(_backlightPin, INPUT);
            digitalWrite(_backlightPin, LOW);

            // Need to re-initialize the backlight at the earliest opportunity.
            backlightInit = false;
        }
        _backlightPin = pin;
    }
}

void LCD::display()
{
    LiquidCrystal::display();
    pinMode(_backlightPin, OUTPUT);
    digitalWrite(_backlightPin, HIGH);
    screenSaved = false;
    backlightInit = true;
    lastRestore = millis();
}

void LCD::noDisplay()
{
    if (mode == DisplayOff)
        LiquidCrystal::noDisplay();
    pinMode(_backlightPin, OUTPUT);
    digitalWrite(_backlightPin, LOW);
    screenSaved = true;
    backlightInit = true;
}

void LCD::setScreenSaverMode(ScreenSaverMode mode)
{
    if (this->mode != mode) {
        this->mode = mode;
        if (screenSaved)
            noDisplay();
        else
            display();
    }
}

void LCD::enableScreenSaver(int timeoutSecs)
{
    if (timeoutSecs < 0)
        timeout = 0;
    else
        timeout = ((unsigned long)timeoutSecs) * 1000;
    display();
}

void LCD::disableScreenSaver()
{
    timeout = 0;
    display();
}

// Button mapping table generated by genlookup.c
static unsigned char const buttonMappings[] PROGMEM = {
    2, 0, 0, 0, 3, 0, 0, 0, 0, 4, 4, 0, 0, 0, 0, 1,
    1, 0, 0, 0, 0, 0, 5, 5, 0, 0, 0, 0, 0, 0, 0, 0
};
#define mapButton(value) (pgm_read_byte(&(buttonMappings[(value) >> 5])))

int LCD::getButton()
{
    // Initialize the backlight for the first time if necessary.
    if (!backlightInit)
        display();

    // Read the currently pressed button.
    int button = mapButton(analogRead(LCD_BUTTON_PIN));

    // Debounce the button state.
    unsigned long currentTime = millis();
    if (button != debounceButton)
        lastDebounce = currentTime;
    debounceButton = button;
    if ((currentTime - lastDebounce) < DEBOUNCE_DELAY)
        button = prevButton;

    // Process the button event if the state has changed.
    if (prevButton == LCD_BUTTON_NONE && button != LCD_BUTTON_NONE) {
        prevButton = button;
        if (screenSaved) {
            // Button pressed when screen saver active.
            if (mode == BacklightOnSelect) {
                // Turn on the back light only if Select was pressed.
                if (button == LCD_BUTTON_SELECT) {
                    pinMode(_backlightPin, OUTPUT);
                    digitalWrite(_backlightPin, HIGH);
                    screenSaved = false;
                    backlightInit = true;
                }
            } else if (mode == DisplayOff) {
                display();
                eatRelease = true;
                return LCD_BUTTON_NONE;
            } else {
                display();
            }
        } else if (mode == BacklightOnSelect && button != LCD_BUTTON_SELECT) {
            eatRelease = false;
            return button;
        }
        eatRelease = false;
        lastRestore = currentTime;
        return button;
    } else if (prevButton != LCD_BUTTON_NONE && button == LCD_BUTTON_NONE) {
        button = -prevButton;
        prevButton = LCD_BUTTON_NONE;
        lastRestore = currentTime;
        if (eatRelease) {
            eatRelease = false;
            return LCD_BUTTON_NONE;
        }
        return button;
    } else {
        if (!screenSaved && prevButton == LCD_BUTTON_NONE &&
                timeout != 0 && (currentTime - lastRestore) >= timeout)
            noDisplay();    // Activate screen saver.
        return LCD_BUTTON_NONE;
    }
}