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Simple input debouncing
#define CHECK_MSEC 5 // Read hardware every 5 msec
#define PRESS_MSEC 10 // Stable time before registering pressed
#define RELEASE_MSEC 100 // Stable time before registering released
// This function reads the key state from the hardware.
extern bool_t RawKeyPressed();
// This holds the debounced state of the key.
bool_t DebouncedKeyPress = false;
// Service routine called every CHECK_MSEC to
// debounce both edges
void DebounceSwitch1(bool_t *Key_changed, bool_t *Key_pressed)
{
static uint8_t Count = RELEASE_MSEC / CHECK_MSEC;
bool_t RawState;
*Key_changed = false;
*Key_pressed = DebouncedKeyPress;
RawState = RawKeyPressed();
if (RawState == DebouncedKeyPress) {
// Set the timer which allows a change from current state.
if (DebouncedKeyPress) Count = RELEASE_MSEC / CHECK_MSEC;
else Count = PRESS_MSEC / CHECK_MSEC;
} else {
// Key has changed - wait for new state to become stable.
if (--Count == 0) {
// Timer expired - accept the change.
DebouncedKeyPress = RawState;
*Key_changed=true;
*Key_pressed=DebouncedKeyPress;
// And reset the timer.
if (DebouncedKeyPress) Count = RELEASE_MSEC / CHECK_MSEC;
else Count = PRESS_MSEC / CHECK_MSEC;
}
}
}
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