Romi32U4 library
PololuBuzzer.cpp
1 // Copyright Pololu Corporation. For more information, see http://www.pololu.com/
2 
3 #include <avr/interrupt.h>
4 #include "PololuBuzzer.h"
5 
6 #ifdef __AVR_ATmega32U4__
7 
8 // PD7 (OC4D)
9 #define BUZZER_DDR DDRD
10 #define BUZZER (1 << PORTD7)
11 
12 #define TIMER4_CLK_8 0x4 // 2 MHz
13 
14 #define ENABLE_TIMER_INTERRUPT() TIMSK4 = (1 << TOIE4)
15 #define DISABLE_TIMER_INTERRUPT() TIMSK4 = 0
16 
17 #else // 168P or 328P
18 
19 // PD3 (OC2B)
20 #define BUZZER_DDR DDRD
21 #define BUZZER (1 << PORTD3)
22 
23 #define TIMER2_CLK_32 0x3 // 500 kHz
24 
25 static const unsigned int cs2_divider[] = {0, 1, 8, 32, 64, 128, 256, 1024};
26 
27 #define ENABLE_TIMER_INTERRUPT() TIMSK2 = (1 << TOIE2)
28 #define DISABLE_TIMER_INTERRUPT() TIMSK2 = 0
29 
30 #endif
31 
32 unsigned char buzzerInitialized = 0;
33 volatile unsigned char buzzerFinished = 1; // flag: 0 while playing
34 const char * volatile buzzerSequence = 0;
35 
36 // declaring these globals as static means they won't conflict
37 // with globals in other .cpp files that share the same name
38 static volatile unsigned int buzzerTimeout = 0; // tracks buzzer time limit
39 static volatile char play_mode_setting = PLAY_AUTOMATIC;
40 
41 extern volatile unsigned char buzzerFinished; // flag: 0 while playing
42 extern const char * volatile buzzerSequence;
43 
44 
45 static volatile unsigned char use_program_space; // boolean: true if we should
46  // use program space
47 
48 // music settings and defaults
49 static volatile unsigned char octave = 4; // the current octave
50 static volatile unsigned int whole_note_duration = 2000; // the duration of a whole note
51 static volatile unsigned int note_type = 4; // 4 for quarter, etc
52 static volatile unsigned int duration = 500; // the duration of a note in ms
53 static volatile unsigned int volume = 15; // the note volume
54 static volatile unsigned char staccato = 0; // true if playing staccato
55 
56 // staccato handling
57 static volatile unsigned char staccato_rest_duration; // duration of a staccato rest,
58  // or zero if it is time to play a note
59 
60 static void nextNote();
61 
62 #ifdef __AVR_ATmega32U4__
63 
64 // Timer4 overflow interrupt
65 ISR (TIMER4_OVF_vect)
66 {
67  if (buzzerTimeout-- == 0)
68  {
69  DISABLE_TIMER_INTERRUPT();
70  sei(); // re-enable global interrupts (nextNote() is very slow)
71  TCCR4B = (TCCR4B & 0xF0) | TIMER4_CLK_8; // select IO clock
72  unsigned int top = (F_CPU/16) / 1000; // set TOP for freq = 1 kHz:
73  TC4H = top >> 8; // top 2 bits... (TC4H temporarily stores top 2 bits of 10-bit accesses)
74  OCR4C = top; // and bottom 8 bits
75  TC4H = 0; // 0% duty cycle: top 2 bits...
76  OCR4D = 0; // and bottom 8 bits
77  buzzerFinished = 1;
78  if (buzzerSequence && (play_mode_setting == PLAY_AUTOMATIC))
79  nextNote();
80  }
81 }
82 
83 #else
84 
85 // Timer2 overflow interrupt
86 ISR (TIMER2_OVF_vect)
87 {
88  if (buzzerTimeout-- == 0)
89  {
90  DISABLE_TIMER_INTERRUPT();
91  sei(); // re-enable global interrupts (nextNote() is very slow)
92  TCCR2B = (TCCR2B & 0xF8) | TIMER2_CLK_32; // select IO clock
93  OCR2A = (F_CPU/64) / 1000; // set TOP for freq = 1 kHz
94  OCR2B = 0; // 0% duty cycle
95  buzzerFinished = 1;
96  if (buzzerSequence && (play_mode_setting == PLAY_AUTOMATIC))
97  nextNote();
98  }
99 }
100 
101 #endif
102 
103 // this is called by playFrequency()
104 inline void PololuBuzzer::init()
105 {
106  if (!buzzerInitialized)
107  {
108  buzzerInitialized = 1;
109  init2();
110  }
111 }
112 
113 // initializes timer4 (32U4) or timer2 (328P) for buzzer control
114 void PololuBuzzer::init2()
115 {
116  DISABLE_TIMER_INTERRUPT();
117 
118 #ifdef __AVR_ATmega32U4__
119  TCCR4A = 0x00; // bits 7 and 6 clear: normal port op., OC4A disconnected
120  // bits 5 and 4 clear: normal port op., OC4B disconnected
121  // bit 3 clear: no force output compare for channel A
122  // bit 2 clear: no force output compare for channel B
123  // bit 1 clear: disable PWM for channel A
124  // bit 0 clear: disable PWM for channel B
125 
126  TCCR4B = 0x04; // bit 7 clear: disable PWM inversion
127  // bit 6 clear: no prescaler reset
128  // bits 5 and 4 clear: dead time prescaler 1
129  // bit 3 clear, 2 set, 1-0 clear: timer clock = CK/8
130 
131  TCCR4C = 0x09; // bits 7 and 6 clear: normal port op., OC4A disconnected
132  // bits 5 and 4 clear: normal port op., OC4B disconnected
133  // bit 3 set, 2 clear: clear OC4D on comp match when upcounting,
134  // set OC4D on comp match when downcounting
135  // bit 1 clear: no force output compare for channel D
136  // bit 0 set: enable PWM for channel 4
137 
138  TCCR4D = 0x01; // bit 7 clear: disable fault protection interrupt
139  // bit 6 clear: disable fault protection mode
140  // bit 5 clear: disable fault protection noise canceler
141  // bit 4 clear: falling edge triggers fault
142  // bit 3 clear: disable fault protection analog comparator
143  // bit 2 clear: fault protection interrupt flag
144  // bit 1 clear, 0 set: select waveform generation mode,
145  // phase- and frequency-correct PWM, TOP = OCR4C,
146  // OCR4D set at BOTTOM, TOV4 flag set at BOTTOM
147 
148  // This sets timer 4 to run in phase- and frequency-correct PWM mode,
149  // where TOP = OCR4C, OCR4D is updated at BOTTOM, TOV1 Flag is set on BOTTOM.
150  // OC4D is cleared on compare match when upcounting, set on compare
151  // match when downcounting; OC4A and OC4B are disconnected.
152 
153  unsigned int top = (F_CPU/16) / 1000; // set TOP for freq = 1 kHz:
154  TC4H = top >> 8; // top 2 bits...
155  OCR4C = top; // and bottom 8 bits
156  TC4H = 0; // 0% duty cycle: top 2 bits...
157  OCR4D = 0; // and bottom 8 bits
158 #else
159  TCCR2A = 0x21; // bits 7 and 6 clear: normal port op., OC4A disconnected
160  // bit 5 set, 4 clear: clear OC2B on comp match when upcounting,
161  // set OC2B on comp match when downcounting
162  // bits 3 and 2: not used
163  // bit 1 clear, 0 set: combine with bit 3 of TCCR2B...
164 
165  TCCR2B = 0x0B; // bit 7 clear: no force output compare for channel A
166  // bit 6 clear: no force output compare for channel B
167  // bits 5 and 4: not used
168  // bit 3 set: combine with bits 1 and 0 of TCCR2A to
169  // select waveform generation mode 5, phase-correct PWM,
170  // TOP = OCR2A, OCR2B set at TOP, TOV2 flag set at BOTTOM
171  // bit 2 clear, 1-0 set: timer clock = clkT2S/32
172 
173  // This sets timer 2 to run in phase-correct PWM mode, where TOP = OCR2A,
174  // OCR2B is updated at TOP, TOV2 Flag is set on BOTTOM. OC2B is cleared
175  // on compare match when upcounting, set on compare match when downcounting;
176  // OC2A is disconnected.
177  // Note: if the PWM frequency and duty cycle are changed, the first
178  // cycle of the new frequency will be at the old duty cycle, since
179  // the duty cycle (OCR2B) is not updated until TOP.
180 
181 
182  OCR2A = (F_CPU/64) / 1000; // set TOP for freq = 1 kHz
183  OCR2B = 0; // 0% duty cycle
184 #endif
185 
186  BUZZER_DDR |= BUZZER; // buzzer pin set as an output
187  sei();
188 }
189 
190 
191 // Set up the timer to play the desired frequency (in Hz or .1 Hz) for the
192 // the desired duration (in ms). Allowed frequencies are 40 Hz to 10 kHz.
193 // volume controls buzzer volume, with 15 being loudest and 0 being quietest.
194 // Note: frequency*duration/1000 must be less than 0xFFFF (65535). This
195 // means that you can't use a max duration of 65535 ms for frequencies
196 // greater than 1 kHz. For example, the max duration you can use for a
197 // frequency of 10 kHz is 6553 ms. If you use a duration longer than this,
198 // you will cause an integer overflow that produces unexpected behavior.
199 void PololuBuzzer::playFrequency(unsigned int freq, unsigned int dur,
200  unsigned char volume)
201 {
202  init(); // initializes the buzzer if necessary
203  buzzerFinished = 0;
204 
205  unsigned int timeout;
206  unsigned char multiplier = 1;
207 
208  if (freq & DIV_BY_10) // if frequency's DIV_BY_10 bit is set
209  { // then the true frequency is freq/10
210  multiplier = 10; // (gives higher resolution for small freqs)
211  freq &= ~DIV_BY_10; // clear DIV_BY_10 bit
212  }
213 
214  unsigned char min = 40 * multiplier;
215  if (freq < min) // min frequency allowed is 40 Hz
216  freq = min;
217  if (multiplier == 1 && freq > 10000)
218  freq = 10000; // max frequency allowed is 10kHz
219 
220 #ifdef __AVR_ATmega32U4__
221  unsigned long top;
222  unsigned char dividerExponent = 0;
223 
224  // calculate necessary clock source and counter top value to get freq
225  top = (unsigned int)(((F_CPU/2 * multiplier) + (freq >> 1))/ freq);
226 
227  while (top > 1023)
228  {
229  dividerExponent++;
230  top = (unsigned int)((((F_CPU/2 >> (dividerExponent)) * multiplier) + (freq >> 1))/ freq);
231  }
232 #else
233  unsigned int top;
234  unsigned char newCS2 = 2; // try prescaler divider of 8 first (minimum necessary for 10 kHz)
235  unsigned int divider = cs2_divider[newCS2];
236 
237  // calculate necessary clock source and counter top value to get freq
238  top = (unsigned int)(((F_CPU/16 * multiplier) + (freq >> 1))/ freq);
239 
240  while (top > 255)
241  {
242  divider = cs2_divider[++newCS2];
243  top = (unsigned int)(((F_CPU/2/divider * multiplier) + (freq >> 1))/ freq);
244  }
245 #endif
246 
247  // set timeout (duration):
248  if (multiplier == 10)
249  freq = (freq + 5) / 10;
250 
251  if (freq == 1000)
252  timeout = dur; // duration for silent notes is exact
253  else
254  timeout = (unsigned int)((long)dur * freq / 1000);
255 
256  if (volume > 15)
257  volume = 15;
258 
259  DISABLE_TIMER_INTERRUPT(); // disable interrupts while writing to registers
260 
261 #ifdef __AVR_ATmega32U4__
262  TCCR4B = (TCCR4B & 0xF0) | (dividerExponent + 1); // select timer 4 clock prescaler: divider = 2^n if CS4 = n+1
263  TC4H = top >> 8; // set timer 4 pwm frequency: top 2 bits...
264  OCR4C = top; // and bottom 8 bits
265  unsigned int width = top >> (16 - volume); // set duty cycle (volume):
266  TC4H = width >> 8; // top 2 bits...
267  OCR4D = width; // and bottom 8 bits
268  buzzerTimeout = timeout; // set buzzer duration
269 
270  TIFR4 |= 0xFF; // clear any pending t4 overflow int.
271 #else
272  TCCR2B = (TCCR2B & 0xF8) | newCS2; // select timer 2 clock prescaler
273  OCR2A = top; // set timer 2 pwm frequency
274  OCR2B = top >> (16 - volume); // set duty cycle (volume)
275  buzzerTimeout = timeout; // set buzzer duration
276 
277  TIFR2 |= 0xFF; // clear any pending t2 overflow int.
278 #endif
279 
280  ENABLE_TIMER_INTERRUPT();
281 }
282 
283 
284 
285 // Determine the frequency for the specified note, then play that note
286 // for the desired duration (in ms). This is done without using floats
287 // and without having to loop. volume controls buzzer volume, with 15 being
288 // loudest and 0 being quietest.
289 // Note: frequency*duration/1000 must be less than 0xFFFF (65535). This
290 // means that you can't use a max duration of 65535 ms for frequencies
291 // greater than 1 kHz. For example, the max duration you can use for a
292 // frequency of 10 kHz is 6553 ms. If you use a duration longer than this,
293 // you will cause an integer overflow that produces unexpected behavior.
294 void PololuBuzzer::playNote(unsigned char note, unsigned int dur,
295  unsigned char volume)
296 {
297  // note = key + octave * 12, where 0 <= key < 12
298  // example: A4 = A + 4 * 12, where A = 9 (so A4 = 57)
299  // A note is converted to a frequency by the formula:
300  // Freq(n) = Freq(0) * a^n
301  // where
302  // Freq(0) is chosen as A4, which is 440 Hz
303  // and
304  // a = 2 ^ (1/12)
305  // n is the number of notes you are away from A4.
306  // One can see that the frequency will double every 12 notes.
307  // This function exploits this property by defining the frequencies of the
308  // 12 lowest notes allowed and then doubling the appropriate frequency
309  // the appropriate number of times to get the frequency for the specified
310  // note.
311 
312  // if note = 16, freq = 41.2 Hz (E1 - lower limit as freq must be >40 Hz)
313  // if note = 57, freq = 440 Hz (A4 - central value of ET Scale)
314  // if note = 111, freq = 9.96 kHz (D#9 - upper limit, freq must be <10 kHz)
315  // if note = 255, freq = 1 kHz and buzzer is silent (silent note)
316 
317  // The most significant bit of freq is the "divide by 10" bit. If set,
318  // the units for frequency are .1 Hz, not Hz, and freq must be divided
319  // by 10 to get the true frequency in Hz. This allows for an extra digit
320  // of resolution for low frequencies without the need for using floats.
321 
322  unsigned int freq = 0;
323  unsigned char offset_note = note - 16;
324 
325  if (note == SILENT_NOTE || volume == 0)
326  {
327  freq = 1000; // silent notes => use 1kHz freq (for cycle counter)
328  playFrequency(freq, dur, 0);
329  return;
330  }
331 
332  if (note <= 16)
333  offset_note = 0;
334  else if (offset_note > 95)
335  offset_note = 95;
336 
337  unsigned char exponent = offset_note / 12;
338 
339  // frequency table for the lowest 12 allowed notes
340  // frequencies are specified in tenths of a Hertz for added resolution
341  switch (offset_note - exponent * 12) // equivalent to (offset_note % 12)
342  {
343  case 0: // note E1 = 41.2 Hz
344  freq = 412;
345  break;
346  case 1: // note F1 = 43.7 Hz
347  freq = 437;
348  break;
349  case 2: // note F#1 = 46.3 Hz
350  freq = 463;
351  break;
352  case 3: // note G1 = 49.0 Hz
353  freq = 490;
354  break;
355  case 4: // note G#1 = 51.9 Hz
356  freq = 519;
357  break;
358  case 5: // note A1 = 55.0 Hz
359  freq = 550;
360  break;
361  case 6: // note A#1 = 58.3 Hz
362  freq = 583;
363  break;
364  case 7: // note B1 = 61.7 Hz
365  freq = 617;
366  break;
367  case 8: // note C2 = 65.4 Hz
368  freq = 654;
369  break;
370  case 9: // note C#2 = 69.3 Hz
371  freq = 693;
372  break;
373  case 10: // note D2 = 73.4 Hz
374  freq = 734;
375  break;
376  case 11: // note D#2 = 77.8 Hz
377  freq = 778;
378  break;
379  }
380 
381  if (exponent < 7)
382  {
383  freq = freq << exponent; // frequency *= 2 ^ exponent
384  if (exponent > 1) // if the frequency is greater than 160 Hz
385  freq = (freq + 5) / 10; // we don't need the extra resolution
386  else
387  freq += DIV_BY_10; // else keep the added digit of resolution
388  }
389  else
390  freq = (freq * 64 + 2) / 5; // == freq * 2^7 / 10 without int overflow
391 
392  if (volume > 15)
393  volume = 15;
394  playFrequency(freq, dur, volume); // set buzzer this freq/duration
395 }
396 
397 
398 
399 // Returns 1 if the buzzer is currently playing, otherwise it returns 0
400 unsigned char PololuBuzzer::isPlaying()
401 {
402  return !buzzerFinished || buzzerSequence != 0;
403 }
404 
405 
406 // Plays the specified sequence of notes. If the play mode is
407 // PLAY_AUTOMATIC, the sequence of notes will play with no further
408 // action required by the user. If the play mode is PLAY_CHECK,
409 // the user will need to call playCheck() in the main loop to initiate
410 // the playing of each new note in the sequence. The play mode can
411 // be changed while the sequence is playing.
412 // This is modeled after the PLAY commands in GW-BASIC, with just a
413 // few differences.
414 //
415 // The notes are specified by the characters C, D, E, F, G, A, and
416 // B, and they are played by default as "quarter notes" with a
417 // length of 500 ms. This corresponds to a tempo of 120
418 // beats/min. Other durations can be specified by putting a number
419 // immediately after the note. For example, C8 specifies C played as an
420 // eighth note, with half the duration of a quarter note. The special
421 // note R plays a rest (no sound).
422 //
423 // Various control characters alter the sound:
424 // '>' plays the next note one octave higher
425 //
426 // '<' plays the next note one octave lower
427 //
428 // '+' or '#' after a note raises any note one half-step
429 //
430 // '-' after a note lowers any note one half-step
431 //
432 // '.' after a note "dots" it, increasing the length by
433 // 50%. Each additional dot adds half as much as the
434 // previous dot, so that "A.." is 1.75 times the length of
435 // "A".
436 //
437 // 'O' followed by a number sets the octave (default: O4).
438 //
439 // 'T' followed by a number sets the tempo (default: T120).
440 //
441 // 'L' followed by a number sets the default note duration to
442 // the type specified by the number: 4 for quarter notes, 8
443 // for eighth notes, 16 for sixteenth notes, etc.
444 // (default: L4)
445 //
446 // 'V' followed by a number from 0-15 sets the music volume.
447 // (default: V15)
448 //
449 // 'MS' sets all subsequent notes to play staccato - each note is played
450 // for 1/2 of its allotted time, followed by an equal period
451 // of silence.
452 //
453 // 'ML' sets all subsequent notes to play legato - each note is played
454 // for its full length. This is the default setting.
455 //
456 // '!' resets all persistent settings to their defaults.
457 //
458 // The following plays a c major scale up and back down:
459 // play("L16 V8 cdefgab>cbagfedc");
460 //
461 // Here is an example from Bach:
462 // play("T240 L8 a gafaeada c+adaeafa <aa<bac#ada c#adaeaf4");
463 void PololuBuzzer::play(const char *notes)
464 {
465  DISABLE_TIMER_INTERRUPT(); // prevent this from being interrupted
466  buzzerSequence = notes;
467  use_program_space = 0;
468  staccato_rest_duration = 0;
469  nextNote(); // this re-enables the timer interrupt
470 }
471 
472 void PololuBuzzer::playFromProgramSpace(const char *notes_p)
473 {
474  DISABLE_TIMER_INTERRUPT(); // prevent this from being interrupted
475  buzzerSequence = notes_p;
476  use_program_space = 1;
477  staccato_rest_duration = 0;
478  nextNote(); // this re-enables the timer interrupt
479 }
480 
481 
482 // stop all sound playback immediately
484 {
485  DISABLE_TIMER_INTERRUPT(); // disable interrupts
486 
487 #ifdef __AVR_ATmega32U4__
488  TCCR4B = (TCCR4B & 0xF0) | TIMER4_CLK_8; // select IO clock
489  unsigned int top = (F_CPU/16) / 1000; // set TOP for freq = 1 kHz:
490  TC4H = top >> 8; // top 2 bits... (TC4H temporarily stores top 2 bits of 10-bit accesses)
491  OCR4C = top; // and bottom 8 bits
492  TC4H = 0; // 0% duty cycle: top 2 bits...
493  OCR4D = 0; // and bottom 8 bits
494 #else
495  TCCR2B = (TCCR2B & 0xF8) | TIMER2_CLK_32; // select IO clock
496  OCR2A = (F_CPU/64) / 1000; // set TOP for freq = 1 kHz
497  OCR2B = 0; // 0% duty cycle
498 #endif
499 
500  buzzerFinished = 1;
501  buzzerSequence = 0;
502 }
503 
504 // Gets the current character, converting to lower-case and skipping
505 // spaces. For any spaces, this automatically increments sequence!
506 static char currentCharacter()
507 {
508  char c = 0;
509  do
510  {
511  if(use_program_space)
512  c = pgm_read_byte(buzzerSequence);
513  else
514  c = *buzzerSequence;
515 
516  if(c >= 'A' && c <= 'Z')
517  c += 'a'-'A';
518  } while(c == ' ' && (buzzerSequence ++));
519 
520  return c;
521 }
522 
523 // Returns the numerical argument specified at buzzerSequence[0] and
524 // increments sequence to point to the character immediately after the
525 // argument.
526 static unsigned int getNumber()
527 {
528  unsigned int arg = 0;
529 
530  // read all digits, one at a time
531  char c = currentCharacter();
532  while(c >= '0' && c <= '9')
533  {
534  arg *= 10;
535  arg += c-'0';
536  buzzerSequence ++;
537  c = currentCharacter();
538  }
539 
540  return arg;
541 }
542 
543 static void nextNote()
544 {
545  unsigned char note = 0;
546  unsigned char rest = 0;
547  unsigned char tmp_octave = octave; // the octave for this note
548  unsigned int tmp_duration; // the duration of this note
549  unsigned int dot_add;
550 
551  char c; // temporary variable
552 
553  // if we are playing staccato, after every note we play a rest
554  if(staccato && staccato_rest_duration)
555  {
556  PololuBuzzer::playNote(SILENT_NOTE, staccato_rest_duration, 0);
557  staccato_rest_duration = 0;
558  return;
559  }
560 
561  parse_character:
562 
563  // Get current character
564  c = currentCharacter();
565  buzzerSequence ++;
566 
567  // Interpret the character.
568  switch(c)
569  {
570  case '>':
571  // shift the octave temporarily up
572  tmp_octave ++;
573  goto parse_character;
574  case '<':
575  // shift the octave temporarily down
576  tmp_octave --;
577  goto parse_character;
578  case 'a':
579  note = NOTE_A(0);
580  break;
581  case 'b':
582  note = NOTE_B(0);
583  break;
584  case 'c':
585  note = NOTE_C(0);
586  break;
587  case 'd':
588  note = NOTE_D(0);
589  break;
590  case 'e':
591  note = NOTE_E(0);
592  break;
593  case 'f':
594  note = NOTE_F(0);
595  break;
596  case 'g':
597  note = NOTE_G(0);
598  break;
599  case 'l':
600  // set the default note duration
601  note_type = getNumber();
602  duration = whole_note_duration/note_type;
603  goto parse_character;
604  case 'm':
605  // set music staccato or legato
606  if(currentCharacter() == 'l')
607  staccato = false;
608  else
609  {
610  staccato = true;
611  staccato_rest_duration = 0;
612  }
613  buzzerSequence ++;
614  goto parse_character;
615  case 'o':
616  // set the octave permanently
617  octave = tmp_octave = getNumber();
618  goto parse_character;
619  case 'r':
620  // Rest - the note value doesn't matter.
621  rest = 1;
622  break;
623  case 't':
624  // set the tempo
625  whole_note_duration = 60*400/getNumber()*10;
626  duration = whole_note_duration/note_type;
627  goto parse_character;
628  case 'v':
629  // set the volume
630  volume = getNumber();
631  goto parse_character;
632  case '!':
633  // reset to defaults
634  octave = 4;
635  whole_note_duration = 2000;
636  note_type = 4;
637  duration = 500;
638  volume = 15;
639  staccato = 0;
640  // reset temp variables that depend on the defaults
641  tmp_octave = octave;
642  tmp_duration = duration;
643  goto parse_character;
644  default:
645  buzzerSequence = 0;
646  return;
647  }
648 
649  note += tmp_octave*12;
650 
651  // handle sharps and flats
652  c = currentCharacter();
653  while(c == '+' || c == '#')
654  {
655  buzzerSequence ++;
656  note ++;
657  c = currentCharacter();
658  }
659  while(c == '-')
660  {
661  buzzerSequence ++;
662  note --;
663  c = currentCharacter();
664  }
665 
666  // set the duration of just this note
667  tmp_duration = duration;
668 
669  // If the input is 'c16', make it a 16th note, etc.
670  if(c > '0' && c < '9')
671  tmp_duration = whole_note_duration/getNumber();
672 
673  // Handle dotted notes - the first dot adds 50%, and each
674  // additional dot adds 50% of the previous dot.
675  dot_add = tmp_duration/2;
676  while(currentCharacter() == '.')
677  {
678  buzzerSequence ++;
679  tmp_duration += dot_add;
680  dot_add /= 2;
681  }
682 
683  if(staccato)
684  {
685  staccato_rest_duration = tmp_duration / 2;
686  tmp_duration -= staccato_rest_duration;
687  }
688 
689  // this will re-enable the timer overflow interrupt
690  PololuBuzzer::playNote(rest ? SILENT_NOTE : note, tmp_duration, volume);
691 }
692 
693 
694 // This puts play() into a mode where instead of advancing to the
695 // next note in the sequence automatically, it waits until the
696 // function playCheck() is called. The idea is that you can
697 // put playCheck() in your main loop and avoid potential
698 // delays due to the note sequence being checked in the middle of
699 // a time sensitive calculation. It is recommended that you use
700 // this function if you are doing anything that can't tolerate
701 // being interrupted for more than a few microseconds.
702 // Note that the play mode can be changed while a sequence is being
703 // played.
704 //
705 // Usage: playMode(PLAY_AUTOMATIC) makes it automatic (the
706 // default), playMode(PLAY_CHECK) sets it to a mode where you have
707 // to call playCheck().
708 void PololuBuzzer::playMode(unsigned char mode)
709 {
710  play_mode_setting = mode;
711 
712  // We want to check to make sure that we didn't miss a note if we
713  // are going out of play-check mode.
714  if(mode == PLAY_AUTOMATIC)
715  playCheck();
716 }
717 
718 
719 // Checks whether it is time to start another note, and starts
720 // it if so. If it is not yet time to start the next note, this method
721 // returns without doing anything. Call this as often as possible
722 // in your main loop to avoid delays between notes in the sequence.
723 //
724 // Returns true if it is still playing.
725 unsigned char PololuBuzzer::playCheck()
726 {
727  if(buzzerFinished && buzzerSequence != 0)
728  nextNote();
729  return buzzerSequence != 0;
730 }
#define DIV_BY_10
frequency bit that indicates Hz/10 e.g. frequency = (445 | DIV_BY_10) gives a frequency of 44...
Definition: PololuBuzzer.h:86
#define SILENT_NOTE
silences buzzer for the note duration
Definition: PololuBuzzer.h:81
static void playMode(unsigned char mode)
Controls whether play() sequence is played automatically or must be driven with playCheck().
#define PLAY_AUTOMATIC
Specifies that the sequence of notes will play with no further action required by the user...
Definition: PololuBuzzer.h:42
static void playNote(unsigned char note, unsigned int duration, unsigned char volume)
Plays the specified note for the specified duration.
static unsigned char playCheck()
Starts the next note in a sequence, if necessary, in PLAY_CHECK mode.
static void playFromProgramSpace(const char *sequence)
Plays the specified sequence of notes from program space.
static unsigned char isPlaying()
Checks whether a note, frequency, or sequence is being played.
static void playFrequency(unsigned int freq, unsigned int duration, unsigned char volume)
Plays the specified frequency for the specified duration.
static void stopPlaying()
Stops any note, frequency, or melody being played.
static void play(const char *sequence)
Plays the specified sequence of notes.