void buzzer_play(note *notes)
{
/* Allow buzzer PWM output on P2.7 */
P2SEL |= BIT7;
/* 0x000F is the "stop bit" */
while (PITCH(*notes) != 0x000F) {
if (PITCH(*notes) == 0) {
/* Stop the timer! We are playing a rest */
TA1CTL &= ~MC_3;
} else {
/* Set PWM frequency */
TA1CCR0 = base_notes[PITCH(*notes)] >> OCTAVE(*notes);
/* Start the timer */
TA1CTL |= MC__UP;
}
/* Delay for DURATION(*notes) milliseconds,
use LPM1 because we need SMCLK for tone generation */
timer0_delay(DURATION(*notes), LPM1_bits);
/* Advance to the next note */
notes++;
}
/* Stop buzzer */
buzzer_stop();
}
void buzzer_callback()
{
/* Start by incrementing the counter; we are playing the next note
* This is here because the index must atually point to the note
* currently playing, so main knows if we can go to LPM3 */
buzzer_counter++;
/* Here the -1 is needed for the offset of buzzer_counter due to the
* increment above. */
note n = *(buzzer_buffer + buzzer_counter - 1);
/* 0x000F is the "stop bit" */
if(PITCH(n) == 0) {
/* Stop buzzer */
buzzer_stop();
return;
}
if (PITCH(n) == 0x000F) {
/* Stop the timer! We are playing a rest */
TA1CTL &= ~MC_3;
} else {
/* Set PWM frequency */
TA1CCR0 = base_notes[PITCH(n)] >> OCTAVE(n);
/* Start the timer */
TA1CTL |= MC__UP;
}
/* Delay for DURATION(*n) milliseconds, */
timer0_delay_callback(DURATION(n), &buzzer_callback);
}
// Play a sequence of MelodyNotes
// Sequence must terminate with octave == -1
void playMelody(prog_uint16_t* notes)
{
int i=0;
while (true) {
uint16_t melody_note = pgm_read_word_near(notes + i);
i++;
uint8_t duration = DURATION(melody_note);
if (duration == 0) {
// Silence the buzzer at the end, in case the sequence did not do so.
playMidiNote(0, NOTE_SILENCE);
return;
}
uint8_t octave = OCTAVE(melody_note);
uint8_t note = NOTE(melody_note);
playMidiNote(octave, note);
// NOTE(mikey): Originally, we used the busy-loop _delay_ms method to avoid
// tmr0. This was blowing up the program size as well.
delay(duration);
}
}