fizban99 / upy-rtttl

Python Parser for Ring Tone Text Transfer Language (RTTTL)

Ring Tone Text Transfer Language Parser

This library can parse RTTTL text lines and delivers the frequency and duration for each note.

A typical RTTTL string looks like this:

Entertainer:d=4,o=5,b=140:8d,8d#,8e,c6,8e,c6,8e,2c.6,8c6,8d6,8d#6,8e6,8c6,8d6,e6,8b,d6,2c6,p,8d,8d#,8e,c6,8e,c6,8e,2c.6,8p,8a,8g,8f#,8a,8c6,e6,8d6,8c6,8a,2d6

You can find many more sample ring tones here: http://www.picaxe.com/RTTTL-Ringtones-for-Tune-Command/

You can find a description of RTTTL here: https://en.wikipedia.org/wiki/Ring_Tone_Transfer_Language

Using RTTTL on the pyboad

Instantiate an instance of the RTTTL class, passing in the tune string to the constructor.

tune = RTTTL('Entertainer:d=4,o=5,b=140:8d,8d#,8e,c6,8e,c6,8e,2c.6,8c6,8d6,8d#6,8e6,8c6,8d6,e6,8b,d6,2c6,p,8d,8d#,8e,c6,8e,c6,8e,2c.6,8p,8a,8g,8f#,8a,8c6,e6,8d6,8c6,8a,2d6')

Then use the notes generator to enumerate the notes in the tune. The notes generator will return a tuple, where the first entry in the tuple contains the frequency of the note (in Hz) and the second entry in the tuple contains the duration of the note.

for freq, msec in tune.notes()
    play_tone(freq, msec)

When using a piezo you basically provide a 50% PWM signal to the piezo using the frequency of the note. Some piezo speakers can vary the volume by using a different duty cycle. The piezo on the G30DEV board I tested this on, it didn't seem to make any difference.

In order to distinguish consequtive notes, you need a small gap between the notes. I chose to use 90% of the duration to play the tone, and 10% of duration to play silence.

I used the following play_tone routine on the G30DEV board:

import pyb
buz_tim = pyb.Timer(3, freq=440)
buz_ch = buz_tim.channel(1, pyb.Timer.PWM, pin=pyb.Pin.board.BUZZER, pulse_width=0)
def play_tone(freq, msec):
    print('freq = {:6.1f} msec = {:6.1f}'.format(freq, msec))
    if freq > 0:
        buz_tim.freq(freq)
        buz_ch.pulse_width_percent(50)
    pyb.delay(int(msec * 0.9))
    buz_ch.pulse_width_percent(0)
    pyb.delay(int(msec * 0.1))

I put a recording of the above on YouTube: https://youtu.be/TadV2AEvfww

The G30DEV board definition files for MicroPython can be found here: https://github.com/dhylands/G30DEV