ESP32 PWM

music.py

from time import sleep
from machine import Pin, PWM
import struct

# Function to calculate the frequency of a musical note based on its MIDI note number
def get_freq(note):
    return int(440 * 2 ** ((note - 69) / 12.0))

# Lists for note offsets and PWM duty values
offset = [0, -24, 0, 0, 0, -12, 12, 24, 36, 0, 0, 0, 0, 0, 0, 0]
duty = [24576, 32768, 0, 0, 0, 24576, 32768, 32768, 32768, 8192, 8192, 32768, 16384, 32768, 16384, 32768]

# Class for managing sound on multiple channels
class SoundManager:
    def __init__(self, *pins):
        self.channels = []
        self.size = len(pins)
        for pin in pins:
            pwm = PWM(Pin(pin))
            pwm.freq(48000)
            self.channels.append(pwm)
        self.active = 0

    def add(self, freq, inst):
        if self.active < self.size:
            self.channels[self.active].duty_u16(duty[inst])
            self.channels[self.active].freq(freq)
            self.active += 1

    def clear(self):
        self.active = 0

    def stop(self):
        for p in self.channels:
            p.freq(48000)
        self.active = 0

# Initialize the SoundManager with specified pins
snd = SoundManager(4, 5, 19, 22)

# Open and read the music file in binary mode
f = open('music/牛仔很忙.mcs', 'rb')

# Read the magic bytes, version, delay, and length from the file
magic = f.read(4)
version, delay, length = struct.unpack("<hfi", f.read(10))
print(version, delay, length)

# Clear any existing sounds
snd.clear()

print(1)

# Function to pause the sound for a specified time
def pause(time):
    sleep(time * 0.05 * delay)
    snd.stop()

# Function to play a note with a given frequency and instrument
def play(freq, inst):
    snd.add(freq, inst)

try:
    while True:
        for i in range(length):
            # Read timing, instrument, and note data from the file
            timing, inst, note = struct.unpack("<hbb", f.read(4))
            print(i, timing, inst, note)

            if inst in (2, 3, 4):  # Check if the instrument is for percussion
                if timing != 0:
                    pause(timing)
                continue

            if version == 0:
                play(get_freq(note + offset[inst]), inst)
                if timing != 0:
                    pause(timing)
            elif version == 1:
                if timing != 0:
                    pause(timing)
                play(get_freq(note + offset[inst]), inst)

        snd.stop()
        sleep(1)
        f.seek(14)
except KeyboardInterrupt:
    snd.stop()