What is it

This is a TDK INMP441 I2S MEMS microphone module that can be used with Sonocotta ESP32 Audio boards. For the ESP32-specific pinout, refer to the board documentation and the silkscreen hints on the board.

Features

• Interface: Digital Output (I2S)
• Sensitivity: -26dB FS ±3dB FS at 1kHz, 94dB SPL
• S/N Ratio [SNR] (Typ.): 61dBA
• Sound Pressure Level: 105dB at THD 3% Max., 1kHz
• Acoustic Overload Point: 120dB SPL at 10% THD
• Total Harmonic Distortion [THD]: 3% Max. at 105dB SPL, 1kHz
• Lower Cutoff Frequency (Min.): 60Hz
• Current Consumption [Icc] (Typ.): 2.2mA
• Operating Temperature Range: -40 to 85°C

Compatibility list

ESP32 Boards

• HiFi ESP32 and HiFi ESP32 Plus
• Loud ESP32 and Loud ESP32 Plus
• Louder ESP32 and Louder ESP32 Plus
• Amped ESP32 and Amped ESP32 Plus

Practical Observations

Most recent revisions of the ESP32 Audio boards have an unsoldered header for external I2S mic: left and right channels. ESP32 uses the same I2S bus with an extra DATA IN pin due to the pin limitations, while S3 uses a dedicated I2S bus. It can be used for wake word functionality in the Home Assistant or for custom firmware.

Note that when purchased together with ESP32 Audio Boards, it would be required to solder the Mic module to the board. It is not a hard task for 100 mil pins, but it requires some experience with a soldering iron.

The mic model that I used for testing and validation is the INMP441 MEMS microphone; the pinout is created for this model. Other models might be available.