import math
import struct
from machine import I2S, Pin

# 1. 設定 I2S 腳位
GPIO_BCK = 2   # SCK
GPIO_LRC = GPIO_BCK + 1   # WS (必須是 ws = sck + 1)
GPIO_DIN = 4   # SD

# 2. 初始化 I2S 介面
# 採樣率 44.1kHz, 16位元, 單聲道 (Mono)
audio_out = I2S(
    0, 
    sck=Pin(GPIO_BCK), 
    ws=Pin(GPIO_LRC), 
    sd=Pin(GPIO_DIN), 
    mode=I2S.TX, 
    bits=16, 
    format=I2S.MONO, 
    rate=44100, 
    ibuf=10240
)

# 3. 產生 440Hz 正弦波數據 (A4 音符)
sample_rate = 44100
frequency = 440
amplitude = 10000 # 音量大小 (最大 32767)

sample_data = bytearray()

def waveform(frequency):
    global sample_data

    # 預先計算一個週期的波形
    samples_per_cycle = sample_rate // frequency

    for i in range(samples_per_cycle):
        sample = int(amplitude * math.sin(2 * math.pi * i / samples_per_cycle))
        # 將整數轉為 16-bit 有符號小端序位元組 (Little-endian)
        sample_data += struct.pack('<h', sample)

print("開始播放測試音...")
waveform(frequency)

# 4. 循環播放
try:
    while True:
        audio_out.write(sample_data)

    # with open("test.wav", "rb") as f:
        # f.seek(44) # 跳過 WAV 標頭 (Header)
        # while True:
            # data = f.read(1024)
            # if not data:
                # break
            # audio_out.write(data)
except KeyboardInterrupt:
    print("停止播放")
    audio_out.deinit()