Seeed Studio XIAO ESP32S3 microphone incompatible with Micropython?

[claudiaeng]

So far, all attempts to read data from the Seeed Studio XIAO ESP32S3 microphone have been unsuccessful. Cannot find any Micropython code samples to reference. I've tried with the pins found in the C sample code, but others have also found that these are incorrect. Is I2S completely incompatible here, or is there something I'm missing? Have tried PDM to PCM conversion, other pins, other buffer sizes, other bit rates, etc. and no data ever comes in. I'm aware that the mic might have a sound threshold. Have tried loud noises as well. Nothing. FYI: I'm using the Micropython firmware provided by Seeed Studio.

Here is some sample code:

import time
from machine import I2S, Pin

# Define GPIO pins for Xiao ESP32S3 Sense
BCLK_PIN = 12  # Bit Clock (SCK)
LRCK_PIN = 11  # Word Select (WS)
DATA_PIN = 13   # Data In (SD)

def initialize_i2s():
    try:
        # Initialize I2S interface
        print("Initializing I2S...")
        i2s = I2S(
            0,                # Use I2S0
            sck=Pin(BCLK_PIN),
            ws=Pin(LRCK_PIN),
            sd=Pin(DATA_PIN),
            mode=I2S.RX,
            bits=16,          # 16 bits per sample
            format=I2S.MONO,  # Mono audio
            rate=16000,       # 16 kHz sample rate
            ibuf=4096,        # Input buffer size
        )
        print("I2S initialized successfully")
        return i2s
    except Exception as e:
        print("I2S Initialization Error:", e)
        return None

def capture_and_print_audio(i2s, num_samples=10):
    if not i2s:
        print("I2S not initialized. Cannot capture audio.")
        return
    print("I2S stabilized. Starting audio capture...")
    try:
        buf = bytearray(2048)  # Buffer for 1024 samples (2 bytes per sample)
        for sample_num in range(num_samples):
            bytes_read = i2s.readinto(buf)
            print(f"Bytes read: {bytes_read}")
            if bytes_read:
                # Print the first 8 bytes for debugging
                print(f"Raw bytes: {buf[:8].hex()}")
                # Print first few sample values
                for i in range(0, min(16, bytes_read), 2):
                    if i+2 > bytes_read:
                        break  # Prevent overflow
                    sample = int.from_bytes(buf[i:i+2], 'little', True)
                    print(f"Audio Sample {i//2 + 1}: {sample}")
            else:
                print("No data read")
            time.sleep(0.1)  # Short delay between captures
    except Exception as e:
        print("Error during audio capture:", e)

def deinitialize_i2s(i2s):
    if i2s:
        try:
            i2s.deinit()
            print("I2S deinitialized successfully")
        except Exception as e:
            print("Error during I2S deinitialization:", e)
    else:
        print("I2S was not initialized; skipping deinitialization.")

def main():
    i2s = initialize_i2s()
    time.sleep(1)  # Allow microphone to stabilize
    capture_and_print_audio(i2s, num_samples=10)
    deinitialize_i2s(i2s)

if __name__ == "__main__":
    main()

[miketeachman]

The microphone on this Seeed Studio product is a PDM microphone. The PDM protocol is not supported by MicroPython. It is not possible to use the machine.I2S class with a PDM microphone.

[claudiaeng]

This was my conclusion but wanted to make sure. Is there a way to write a C module to get this working without being disruptive to my other functionality? Thanks @miketeachman for the quick response!!

[mattytrentini]

FWIW adding general PDM support would be a very desirable feature 😉

[sophiedegran]

Claudia have a look to the #14176

[claudiaeng]

I'm testing this out before abandoning the mic altogether! Thanks @sophiedegran

[sosi-deadeye]

You can use it now, if you use Circuitpython instead of Micropython.
Library-Docs: https://docs.circuitpython.org/en/latest/shared-bindings/audiobusio/

Circuitpython is not a drop-in replacement. Keep this in mind.

[jonnor]

audiobus.PDMIn documentations say under Limitations: ".... Not available on Espressif". So it sounds like it is not implemented for ESP32?