no change on INMP441 microphone result

[ebad84]

hi, i'm working with INMP441 microphone on raspberry pi pico, and i connected the microphone by what should it be, but when i run the record_mic_to_sdcard_blocking.py file, the result is not what it supposed to be so i added a print after while num_sample_bytes_written_to_wav < RECORDING_SIZE_IN_BYTES: here's the output :

>>> %Run -c $EDITOR_CONTENT
Recording size: 441000 bytes
==========  START RECORDING ==========
10000
10000
10000
10000
10000
10000
10000
10000
10000
10000
10000
10000
10000
10000
10000
10000
10000
10000
10000
10000
10000
10000
10000
10000
10000
10000
10000
10000
10000
10000
10000
10000
10000
10000
10000
10000
10000
10000
10000
10000
10000
10000
10000
10000
10000
==========  DONE RECORDING ==========
>>> 

i checked that if i disconnect INMP441 from wires, what happens. and the output wasn't changed at all. only 10000 was printed on each line. i don't think the problem should be from sd card

MicroPython v1.20.0 on 2023-04-26; Raspberry Pi Pico with RP2040

Type "help()" for more information.

thank you and sorry for my poor english🙏

[ebad84]

here's my code :

# The MIT License (MIT)
# Copyright (c) 2022 Mike Teachman
# https://opensource.org/licenses/MIT

# Purpose: Read audio samples from an I2S microphone and write to SD card
#
# - read 32-bit audio samples from I2S hardware, typically an I2S MEMS Microphone
# - convert 32-bit samples to specified bit size
# - write samples to a SD card file in WAV format
# - samples will be continuously written to the WAV file
#   until a keyboard interrupt (ctrl-c) is detected
#
# Blocking version
# - the readinto() method blocks until
#   the supplied buffer is filled

import os
from machine import Pin
from machine import I2S


if os.uname().machine.count("Raspberry"):
    from sdcard import SDCard
    from machine import SPI

    cs = Pin(9, machine.Pin.OUT)
    spi = SPI(
        1,
        baudrate=1_000_000,  # this has no effect on spi bus speed to SD Card
        polarity=0,
        phase=0,
        bits=8,
        firstbit=machine.SPI.MSB,
        sck=Pin(10),
        mosi=Pin(11),
        miso=Pin(8),
    )

    sd = SDCard(spi, cs)
#     sd.init_spi(25_000_000)  # increase SPI bus speed to SD card
    os.mount(sd, "/sd")

    # ======= I2S CONFIGURATION =======
    SCK_PIN = 16
    WS_PIN = 17
    SD_PIN = 18
    I2S_ID = 0
    BUFFER_LENGTH_IN_BYTES = 60000  # larger buffer to accommodate slow SD card driver
    # ======= I2S CONFIGURATION =======


# ======= AUDIO CONFIGURATION =======
WAV_FILE = "mic.wav"
RECORD_TIME_IN_SECONDS = 10
WAV_SAMPLE_SIZE_IN_BITS = 32
FORMAT = I2S.MONO
SAMPLE_RATE_IN_HZ = 22_050
# ======= AUDIO CONFIGURATION =======

format_to_channels = {I2S.MONO: 1, I2S.STEREO: 2}
NUM_CHANNELS = format_to_channels[FORMAT]
WAV_SAMPLE_SIZE_IN_BYTES = WAV_SAMPLE_SIZE_IN_BITS // 8
RECORDING_SIZE_IN_BYTES = (
    RECORD_TIME_IN_SECONDS * SAMPLE_RATE_IN_HZ * WAV_SAMPLE_SIZE_IN_BYTES * NUM_CHANNELS
)


def create_wav_header(sampleRate, bitsPerSample, num_channels, num_samples):
    datasize = num_samples * num_channels * bitsPerSample // 8
    o = bytes("RIFF", "ascii")  # (4byte) Marks file as RIFF
    o += (datasize + 36).to_bytes(
        4, "little"
    )  # (4byte) File size in bytes excluding this and RIFF marker
    o += bytes("WAVE", "ascii")  # (4byte) File type
    o += bytes("fmt ", "ascii")  # (4byte) Format Chunk Marker
    o += (16).to_bytes(4, "little")  # (4byte) Length of above format data
    o += (1).to_bytes(2, "little")  # (2byte) Format type (1 - PCM)
    o += (num_channels).to_bytes(2, "little")  # (2byte)
    o += (sampleRate).to_bytes(4, "little")  # (4byte)
    o += (sampleRate * num_channels * bitsPerSample // 8).to_bytes(4, "little")  # (4byte)
    o += (num_channels * bitsPerSample // 8).to_bytes(2, "little")  # (2byte)
    o += (bitsPerSample).to_bytes(2, "little")  # (2byte)
    o += bytes("data", "ascii")  # (4byte) Data Chunk Marker
    o += (datasize).to_bytes(4, "little")  # (4byte) Data size in bytes
    return o


wav = open("/sd/{}".format(WAV_FILE), "wb")

# create header for WAV file and write to SD card
wav_header = create_wav_header(
    SAMPLE_RATE_IN_HZ,
    WAV_SAMPLE_SIZE_IN_BITS,
    NUM_CHANNELS,
    SAMPLE_RATE_IN_HZ * RECORD_TIME_IN_SECONDS,
)
num_bytes_written = wav.write(wav_header)

SCK_PIN = 19
WS_PIN = 20
SD_PIN = 21
I2S_ID = 0

audio_in = I2S(
    I2S_ID,
    sck=Pin(SCK_PIN),
    ws=Pin(WS_PIN),
    sd=Pin(SD_PIN),
    mode=I2S.RX,
    bits=WAV_SAMPLE_SIZE_IN_BITS,
    format=FORMAT,
    rate=SAMPLE_RATE_IN_HZ,
    ibuf=BUFFER_LENGTH_IN_BYTES,
)

# allocate sample arrays
# memoryview used to reduce heap allocation in while loop
mic_samples = bytearray(10000)
mic_samples_mv = memoryview(mic_samples)

num_sample_bytes_written_to_wav = 0

print("Recording size: {} bytes".format(RECORDING_SIZE_IN_BYTES))
print("==========  START RECORDING ==========")
try:
    while num_sample_bytes_written_to_wav < RECORDING_SIZE_IN_BYTES:
        # read a block of samples from the I2S microphone
        num_bytes_read_from_mic = audio_in.readinto(mic_samples_mv)
        print(num_bytes_read_from_mic)
        if num_bytes_read_from_mic > 0:
            num_bytes_to_write = min(
                num_bytes_read_from_mic, RECORDING_SIZE_IN_BYTES - num_sample_bytes_written_to_wav
            )
            # write samples to WAV file
            num_bytes_written = wav.write(mic_samples_mv[:num_bytes_to_write])
            num_sample_bytes_written_to_wav += num_bytes_written

    print("==========  DONE RECORDING ==========")
except (KeyboardInterrupt, Exception) as e:
    print("caught exception {} {}".format(type(e).__name__, e))

# exit()

# cleanup
wav.close()
if os.uname().machine.count("PYBD"):
    os.umount("/sd")
elif os.uname().machine.count("ESP32"):
    os.umount("/sd")
    sd.deinit()
elif os.uname().machine.count("Raspberry"):
    os.umount("/sd")
    spi.deinit()
elif os.uname().machine.count("MIMXRT"):
    os.umount("/sd")
    sd.deinit()
audio_in.deinit()

[ebad84]

Could someone please help me in solving my problem? I'm trying to create a wake word detection using MicroPython, with inmp441. Is there anyone who can assist me in resolving this issue?

[jimtal001]

Hello ebad84,

Did you find the solution to this issue? If so, please share it with us. Thanks!

[jimtal001]

OK, I see that you are printing the wrong variable. I believe you need to print: mic_samples_mv.
num_bytes_read_from_mic will always be a constant value.

[ebad84]

@jimtal001 I tried every variable that I could, no change on output Also I tried an arduino script and it worked pretty well. If you want I can send it Have you succeeded in it?

[jimtal001]

I will be experimenting over the next few days if I have good results I will let you know.

On Sat, Feb 10, 2024, 13:42 Mohammad Reza Ebadollah < @.***> wrote:

@jimtal001 https://github.com/jimtal001 I tried every variable that I could, no change on output Also I tried an arduino script and it worked pretty well. If you want I can send it Have you succeeded in it?

— Reply to this email directly, view it on GitHub https://github.com/miketeachman/micropython-i2s-examples/issues/25#issuecomment-1937104646, or unsubscribe https://github.com/notifications/unsubscribe-auth/AB5LB7XSAL4ZPRZVWOKAL7TYS7ESTAVCNFSM6AAAAAA3RH6VXWVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMYTSMZXGEYDINRUGY . You are receiving this because you were mentioned.Message ID: @.***>

[ebad84]

@jimtal001 ok

[jimtal001]

try changing your I2S_ID from 0 to 1