Plays "silent night" on a piezo buzzer attached to pin 18 of the Onion Omega2

silent-night-omega2.py

#!/usr/bin/env python
# Plays "silent night" on a piezo buzzer attached to pin 18 of the Onion Omega2
# Things required: python lite, pwm needs to be enabled via:
# omega2-ctrl gpiomux set pwm0 pwm

from time import sleep

exportStr="/sys/class/pwm/pwmchip0/export"
periodStr="/sys/class/pwm/pwmchip0/pwm%s/period"
dutyStr="/sys/class/pwm/pwmchip0/pwm%s/duty_cycle"
enableStr="/sys/class/pwm/pwmchip0/pwm%s/enable"
unexportStr="/sys/class/pwm/pwmchip0/unexport"

# set a PWM channel to a duty cycle and frequency
def setPwmChannel( channel, duty, freq ):
    period = 1.0 / freq * 1000000000
    pulseWidth = period * duty / 100.0
    period = int(period)
    pulseWidth = int(pulseWidth)

    # set the PWM
    with open(exportStr,"w") as exportFile:
        exportFile.write( str(channel) + "\n" )
    with open(periodStr%str(channel),"w") as periodFile:
        periodFile.write( str(period) + "\n" )
    with open(dutyStr%str(channel),"w") as dutyFile:
        dutyFile.write( str(pulseWidth) + "\n" )
    with open(enableStr%str(channel),"w") as enableFile:
        enableFile.write( "1\n" )
    with open(unexportStr,"w") as unexportFile:
        unexportFile.write( str(channel) + "\n" )

def disablePwmChannel( channel ):
    # disable the PWM chanel
    with open(exportStr,"w") as exportFile:
        exportFile.write( str(channel) + "\n" )
    with open(enableStr%str(channel),"w") as enableFile:
        enableFile.write( "0\n" )
    with open(unexportStr,"w") as unexportFile:
        unexportFile.write( str(channel) + "\n" )

notes = {
    "cL": 129,
    "cLS": 139,
    "dL": 146,
    "dLS": 156,
    "eL": 163,
    "fL": 173,
    "fLS": 185,
    "gL": 194,
    "gLS": 207,
    "aL": 219,
    "aLS": 228,
    "bL": 232,

    "c": 261,
    "cS": 277,
    "d": 294,
    "dS": 311,
    "e": 329,
    "f": 349,
    "fS": 370,
    "g": 391,
    "gS": 415,
    "a": 440,
    "aS": 455,
    "b": 466,

    "cH": 523,
    "cHS": 554,
    "dH": 587,
    "dHS": 622,
    "eH": 659,
    "fH": 698,
    "fHS": 740,
    "gH": 784,
    "gHS": 830,
    "aH": 880,
    "aHS": 910,
    "bH": 933
    }

def beep( note, duration ):
    if note == "pause":
        sleep( duration / 1000.0 )
        return
    setPwmChannel( 0, 50, notes[note] )
    sleep( duration / 1000.0 )
    disablePwmChannel( 0 )
    sleep( 0.02 )

song = [
    ( "f",750 ), # si-
    ( "g",250 ),
    ( "f",500 ), # lent

    ( "d",1500 ), # night

    ( "f",750 ), # ho-
    ( "g",250 ),
    ( "f",500 ), # ly

    ( "d",1500 ), # night

    ( "cH",1000 ), # all
    ( "cH",500 ), # is

    ( "a",1500 ), # calm

    ( "aS",1000 ), # all
    ( "aS",500 ), # is

    ( "f",1000 ), # bright
    ( "pause", 500 ),

    ( "g",1000 ), # round
    ( "g",500 ), # you

    ( "aS",750 ), # vir-
    ( "a",250 ),
    ( "g",500 ), # gin

    ( "f",750 ), # moth-
    ( "g",250 ), # er
    ( "f",500 ), # and

    ( "d",1000 ), # child
    ( "pause", 500 ),

    ( "g",1000 ), # ho-
    ( "g",500 ), # ly

    ( "aS",750 ), # in-
    ( "a",250 ), # fant
    ( "g",500 ), # so

    ( "f",750 ), # ten-
    ( "g",250 ), # der
    ( "f",500 ), # and

    ( "d",1500 ), # mild

    ( "cH",1000 ), # sleep
    ( "cH",500 ), # in

    ( "dHS",750 ), # heav-
    ( "cH",250 ), # en-
    ( "a",500 ), # ly

    ( "aS",1500 ), # peace
    ( "dH",1500 ),

    ( "aS",500 ), # Sleep
    ( "f",500 ),
    ( "d",500 ), # in

    ( "f",750 ), # heav-
    ( "dS",250 ), # en-
    ( "c",500 ), # ly

    ( "bL",1500 ) # peace
    ]

map( lambda x: beep(x[0],x[1]),song )