Merge pull request #5 from tannewt/pwm_support

Support PWM output.

Author: kattni

adafruit_rtttl.py

@@ -32,37 +32,76 @@
 __repo__ = "https://github.com/adafruit/Adafruit_CircuitPython_RTTTL"
 
 import time
-from adafruit_waveform import sine
-import audioio
-
-PIANO = {"4a#": 466.16,
-         "4b" : 493.88,
-         "5c" : 523.25,
-         "5c#": 554.37,
-         "5d" : 587.33,
-         "5d#": 622.25,
-         "5e" : 659.26,
-         "5f" : 698.46,
-         "5f#": 739.99,
-         "5g" : 783.99,
-         "5g#": 830.61,
+import pulseio
+
+AUDIOIO_AVAILABLE = False
+try:
+    import audioio
+    from adafruit_waveform import sine
+    AUDIOIO_AVAILABLE = True
+except ImportError:
+    pass
+
+PIANO = {"4c" : 261.626,
+         "4c#": 277.183,
+         "4d" : 293.665,
+         "4d#": 311.127,
+         "4e" : 329.628,
+         "4f" : 349.228,
+         "4f#": 369.994,
+         "4g" : 391.995,
+         "4g#": 415.305,
+         "4a" : 440,
+         "4a#": 466.164,
+         "4b" : 493.883,
+         "5c" : 523.251,
+         "5c#": 554.365,
+         "5d" : 587.330,
+         "5d#": 622.254,
+         "5e" : 659.255,
+         "5f" : 698.456,
+         "5f#": 739.989,
+         "5g" : 783.991,
+         "5g#": 830.609,
          "5a" : 880,
-         "5a#": 932.33,
-         "5b" : 987.77,
-         "6c" : 1046.5,
-         "6c#": 1108.7,
-         "6d" : 1174.7,
-         "6d#": 1244.5,
-         "6e" : 1318.5,
-         "6f" : 1396.9,
-         "6f#": 1480,
-         "6g" : 1568,
-         "6g#": 1661.2,
+         "5a#": 932.328,
+         "5b" : 987.767,
+         "6c" : 1046.50,
+         "6c#": 1108.73,
+         "6d" : 1174.66,
+         "6d#": 1244.51,
+         "6e" : 1318.51,
+         "6f" : 1396.91,
+         "6f#": 1479.98,
+         "6g" : 1567.98,
+         "6g#": 1661.22,
          "6a" : 1760,
-         "6a#": 1864.7,
-         "6b" : 1975.5,
+         "6a#": 1864.66,
+         "6b" : 1975.53,
          "7c" : 2093,
-         "7c#": 2217.5}
+         "7c#": 2217.46}
+
+def _parse_note(note, duration=2, octave="6"):
+    note = note.strip()
+    piano_note = None
+    note_duration = duration
+    if note[0].isdigit() and note[1].isdigit():
+        note_duration = int(note[:2])
+        piano_note = note[2]
+    elif note[0].isdigit():
+        note_duration = int(note[0])
+        piano_note = note[1]
+    else:
+        piano_note = note[0]
+    if "." in note:
+        note_duration *= 1.5
+    if "#" in note:
+        piano_note += "#"
+    note_octave = octave
+    if note[-1].isdigit():
+        note_octave = note[-1]
+    piano_note = note_octave + piano_note
+    return piano_note, note_duration
 
 def _get_wave(tune, octave):
     """Returns the proper waveform to play the song along with the minimum
@@ -71,17 +110,7 @@ def _get_wave(tune, octave):
     min_freq = 13000
 
     for note in tune.split(","):
-        piano_note = None
-        if note[0].isdigit():
-            piano_note = note[1]
-        else:
-            piano_note = note[0]
-        if "#" in note:
-            piano_note += "#"
-        note_octave = octave
-        if note[-1].isdigit():
-            note_octave = note[-1]
-        piano_note = note_octave + piano_note
+        piano_note, _ = _parse_note(note, octave=octave)
         if piano_note[-1] != "p" and PIANO[piano_note] < min_freq:
             min_freq = PIANO[piano_note]
     return sine.sine_wave(16000, min_freq), min_freq
@@ -91,28 +120,22 @@ def _get_wave(tune, octave):
 def _play_to_pin(tune, base_tone, min_freq, duration, octave, tempo):
     """Using the prepared input send the notes to the pin
     """
+    pwm = isinstance(base_tone, pulseio.PWMOut)
     for note in tune.split(","):
-        piano_note = None
-        note_duration = duration
-        if note[0].isdigit():
-            note_duration = int(note[0])
-            piano_note = note[1]
-        else:
-            piano_note = note[0]
-        if "." in note:
-            note_duration *= 1.5
-        if "#" in note:
-            piano_note += "#"
-        note_octave = octave
-        if note[-1].isdigit():
-            note_octave = note[-1]
-        piano_note = note_octave + piano_note
+        piano_note, note_duration = _parse_note(note, duration, octave)
         if piano_note in PIANO:
-            base_tone.frequency = int(16000 * (PIANO[piano_note] / min_freq))
-            base_tone.play(loop=True)
+            if pwm:
+                base_tone.frequency = int(PIANO[piano_note])
+                base_tone.duty_cycle = 2 ** 15
+            else:
+                base_tone.frequency = int(16000 * (PIANO[piano_note] / min_freq))
+                base_tone.play(loop=True)
         print(piano_note, note_duration)
         time.sleep(4 / note_duration * 60 / tempo)
-        base_tone.stop()
+        if pwm:
+            base_tone.duty_cycle = 0
+        else:
+            base_tone.stop()
         time.sleep(0.02)
 
 #pylint: disable-msg=too-many-arguments
@@ -124,7 +147,7 @@ def play(pin, rtttl, octave=None, duration=None, tempo=None):
     :param int duration: length of notes (default 4 quarter note)
     :param int tempo: how fast (default 63 beats per minute)
     """
-    _, defaults, tune = rtttl.split(":")
+    _, defaults, tune = rtttl.lower().split(":")
     for default in defaults.split(","):
         if default[0] == "d" and not duration:
             duration = int(default[2:])
@@ -141,8 +164,18 @@ def play(pin, rtttl, octave=None, duration=None, tempo=None):
 
     print("tempo", tempo, "octave", octave, "duration", duration)
 
-    wave, min_freq = _get_wave(tune, octave)
+    base_tone = None
+    min_freq = 440
+    if AUDIOIO_AVAILABLE:
+        wave, min_freq = _get_wave(tune, octave)
+        try:
+            base_tone = audioio.AudioOut(pin, wave)
+        except ValueError:
+            # No DAC on the pin so use PWM.
+            pass
 
-    base_tone = audioio.AudioOut(pin, wave)
+    # Fall back to PWM
+    if not base_tone:
+        base_tone = pulseio.PWMOut(pin, duty_cycle=0, variable_frequency=True)
 
     _play_to_pin(tune, base_tone, min_freq, duration, octave, tempo)

docs/conf.py

@@ -15,7 +15,7 @@
     'sphinx.ext.viewcode',
 ]
 
-autodoc_mock_imports = ["audioio", "adafruit_waveform"]
+autodoc_mock_imports = ["audioio", "adafruit_waveform", "pulseio"]
 
 intersphinx_mapping = {'python': ('https://docs.python.org/3.4', None),'CircuitPython': ('https://circuitpython.readthedocs.io/en/latest/', None)}