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Debounce the button state in FreetronicsLCD class

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This commit is contained in:
Rhys Weatherley 2012-05-10 11:34:50 +10:00
parent 45becdfc0e
commit 3487e6ec61
2 changed files with 23 additions and 3 deletions
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24
libraries/FreetronicsLCD/FreetronicsLCD.cpp
View File

@ -33,6 +33,8 @@
#define LCD_BUTTON_LEFT_VALUE 505 #define LCD_BUTTON_LEFT_VALUE 505
#define LCD_BUTTON_SELECT_VALUE 741 #define LCD_BUTTON_SELECT_VALUE 741
#define DEBOUNCE_DELAY 10 // Delay in ms to debounce buttons
/** /**
* \class FreetronicsLCD FreetronicsLCD.h <FreetronicsLCD.h> * \class FreetronicsLCD FreetronicsLCD.h <FreetronicsLCD.h>
* \brief Enhanced library for Freetronics 16x2 LCD shields * \brief Enhanced library for Freetronics 16x2 LCD shields
@ -123,6 +125,8 @@ void FreetronicsLCD::init()
pinMode(LCD_BUTTON_PIN, INPUT); pinMode(LCD_BUTTON_PIN, INPUT);
digitalWrite(LCD_BUTTON_PIN, LOW); digitalWrite(LCD_BUTTON_PIN, LOW);
prevButton = LCD_BUTTON_NONE; prevButton = LCD_BUTTON_NONE;
debounceButton = LCD_BUTTON_NONE;
lastDebounce = 0;
eatRelease = false; eatRelease = false;
// Initialize screen saver. // Initialize screen saver.
@ -224,10 +228,14 @@ void FreetronicsLCD::disableScreenSaver()
* will "eat" the button press and return LCD_BUTTON_NONE. The scrren saver * will "eat" the button press and return LCD_BUTTON_NONE. The scrren saver
* can also be deactivated under program control by calling display() * can also be deactivated under program control by calling display()
* *
* This function debounces the button state automatically so there is no
* need for the caller to worry about spurious button events.
*
* \sa enableScreenSaver(), display(), Form::dispatch() * \sa enableScreenSaver(), display(), Form::dispatch()
*/ */
int FreetronicsLCD::getButton() int FreetronicsLCD::getButton()
{ {
// Read the currently pressed button.
int value = analogRead(LCD_BUTTON_PIN); int value = analogRead(LCD_BUTTON_PIN);
int button; int button;
if (value < (LCD_BUTTON_RIGHT_VALUE + LCD_BUTTON_VALUE_GAP)) if (value < (LCD_BUTTON_RIGHT_VALUE + LCD_BUTTON_VALUE_GAP))
@ -246,6 +254,16 @@ int FreetronicsLCD::getButton()
button = LCD_BUTTON_SELECT; button = LCD_BUTTON_SELECT;
else else
button = LCD_BUTTON_NONE; button = LCD_BUTTON_NONE;
// 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) { if (prevButton == LCD_BUTTON_NONE && button != LCD_BUTTON_NONE) {
prevButton = button; prevButton = button;
if (screenSaved) { if (screenSaved) {
@ -255,12 +273,12 @@ int FreetronicsLCD::getButton()
return LCD_BUTTON_NONE; return LCD_BUTTON_NONE;
} }
eatRelease = false; eatRelease = false;
lastRestore = millis(); lastRestore = currentTime;
return button; return button;
} else if (prevButton != LCD_BUTTON_NONE && button == LCD_BUTTON_NONE) { } else if (prevButton != LCD_BUTTON_NONE && button == LCD_BUTTON_NONE) {
button = -prevButton; button = -prevButton;
prevButton = LCD_BUTTON_NONE; prevButton = LCD_BUTTON_NONE;
lastRestore = millis(); lastRestore = currentTime;
if (eatRelease) { if (eatRelease) {
eatRelease = false; eatRelease = false;
return LCD_BUTTON_NONE; return LCD_BUTTON_NONE;
@ -268,7 +286,7 @@ int FreetronicsLCD::getButton()
return button; return button;
} else { } else {
if (!screenSaved && prevButton == LCD_BUTTON_NONE && if (!screenSaved && prevButton == LCD_BUTTON_NONE &&
timeout != 0 && (millis() - lastRestore) >= timeout) timeout != 0 && (currentTime - lastRestore) >= timeout)
noDisplay(); // Activate screen saver. noDisplay(); // Activate screen saver.
return LCD_BUTTON_NONE; return LCD_BUTTON_NONE;
} }

2
libraries/FreetronicsLCD/FreetronicsLCD.h
View File

@ -61,8 +61,10 @@ public:
private: private:
int prevButton; int prevButton;
int debounceButton;
unsigned long timeout; unsigned long timeout;
unsigned long lastRestore; unsigned long lastRestore;
unsigned long lastDebounce;
bool screenSaved; bool screenSaved;
bool eatRelease; bool eatRelease;