/**
* This function calls ButtonsCheckEvents() once per call and returns which, if any,
* of the Morse code events listed in the enum above have been encountered. It checks for BTN4
* events in its input and should be called at 100Hz so that the timing works. The
* length that BTN4 needs to be held down for a dot is >= 0.25s and < 0.50s with a dash being a button
* down event for >= 0.5s. The button uptime various between dots/dashes (>= .5s), letters
* (>= 1s), and words (>= 2s).
*
* @note This function assumes that the buttons are all unpressed at startup, so that the first
* event it will see is a BUTTON_EVENT_*DOWN.
*
* So pressing the button for 0.1s, releasing it for 0.1s, pressing it for 0.3s, and then waiting
* will decode the string '.-' (A). It will trigger the following order of events:
* 9 MORSE_EVENT_NONEs, 1 MORSE_EVENT_DOT, 39 MORSE_EVENT_NONEs, a MORSE_EVENT_DASH, 69
* MORSE_EVENT_NONEs, a MORSE_EVENT_END_CHAR, and then MORSE_EVENT_INTER_WORDs.
*
* @return The MorseEvent that occurred.
*/
MorseEvent MorseCheckEvents(void) {
switch (myState) {
case(WAITING):
{// if in the state of waiting
if (ButtonsCheckEvents() == BUTTON_EVENT_4DOWN) {
myState = DOT;
myCount = 0;
}
return MORSE_EVENT_NONE;
break;
}
case(DOT):
{
// in the state of dot
myCount += 1;
if (myCount >= MORSE_EVENT_LENGTH_DOWN_DOT) {
myState = DASH;
}
if (ButtonsCheckEvents() == BUTTON_EVENT_4UP) {
// Chenge into Inter letter
myState = INTER_LETTER;
myCount = 0;
return MORSE_EVENT_DOT;
}
return MORSE_EVENT_NONE;
break;
}
case(DASH):
{
//in Dash state
if (ButtonsCheckEvents() == BUTTON_EVENT_4UP) {
// change my state to Inter letter
myState = INTER_LETTER;
myCount = 0;
return MORSE_EVENT_DASH;
}
return MORSE_EVENT_NONE;
break;
}
case(INTER_LETTER):
{
//In the inter letter state
myCount += 1;
if (myCount > MORSE_EVENT_LENGTH_UP_INTER_WORD) {
//if inter letter time out, we go to
myState = WAITING;
return MORSE_EVENT_INTER_WORD;
} else if (ButtonsCheckEvents() == BUTTON_EVENT_4DOWN) {
//
if (myCount > MORSE_EVENT_LENGTH_UP_INTER_LETTER) {
myCount = 0;
myState = DOT;
// return inter ltter event
return MORSE_EVENT_INTER_LETTER;
}
myCount = 0;
myState = DOT;
}
return MORSE_EVENT_NONE;
break;
}
default:
{
//In the deflaut state
FATAL_ERROR();
break;
}
}
}
/**
* Timer2 interrupt. Checks for button events.
*/
void __ISR(_TIMER_2_VECTOR, ipl4) TimerInterrupt100Hz(void)
{
// Clear the interrupt flag.
IFS0CLR = 1 << 8;
buttonEvents = ButtonsCheckEvents();
}
