GY-SPH0645LM4H MEMS Microphone Digital Sound Sensor Module I2S Interface

Specifications

• Interface: I2S (Digital Audio).

• Sensor Type: MEMS (Micro-Electro-Mechanical Systems).

• Operating Voltage: 3.3V DC (NOT 5V compatible).

• Frequency Response: 50Hz – 15kHz (Wideband).

• Sensitivity: -26 dBFS.

• S/N Ratio: 65dB (Very low noise floor).

• Data Format: 24-bit I2S data frames.

• Dimensions: Tiny! ~15mm x 15mm.

Compatibility & Platform Support

• ESP32:Perfect Match. The ESP32 has hardware I2S support. This is the #1 choice for Wi-Fi walkie-talkies or streaming radios.

• Raspberry Pi (Zero/3/4/5): Excellent. The Pi has a dedicated I2S bus on the GPIO header. You can configure this as a system-level sound card (ALSA device).

• Arduino Uno/Nano: Not Compatible. Standard 8-bit Arduinos are too slow and lack the I2S interface to handle this data stream.

• Teensy / STM32:Compatible (Requires specific I2S libraries).

Key Applications & Projects

• DIY Smart Speaker: Build your own privacy-focused version of Alexa or Google Home using a Raspberry Pi.

• Audio Visualizer: Create a real-time LED music visualizer that reacts to specific frequencies (Bass/Treble) with high precision.

• Environmental Monitor: Detect specific sounds (like glass breaking or a baby crying) using Machine Learning on the Edge (TinyML).

• Voice Recorder: Build a high-fidelity dictaphone.

Unlock New Capabilities (Project Evolution)

• Prerequisites: You must be comfortable with installing libraries (I2S for ESP32) or editing config files (/boot/config.txt on Raspberry Pi).

• The Upgrade: Stereo Recording!

• The Logic: The module has a SEL (Select) pin. Connect one mic's SEL to GND (Left Channel) and another mic's SEL to 3.3V (Right Channel). Wire them to the same I2S bus, and boom—you have True Stereo Recording for spatial audio projects.

Virtual Technician: Wiring & Safety ⚠️

• 3V: Connect to 3.3V. DO NOT connect to 5V; it will fry the MEMS chip instantly.

• GND: Connect to Ground.

• BCLK: Bit Clock (Connect to SCK/BCLK pin).

• DOUT: Data Out (Connect to SD/DIN pin).

• LRCL: Left/Right Clock (Connect to WS/Word Select pin).

• SEL: Channel Select. Leave unconnected for Mono/Left. Connect to 3.3V for Right channel.

Accessories

• Included in the Package:

  • 1 x GY-SPH0645LM4H Module

  • 1 x Header Pin Strip (Unsoldered)

• Required Accessories:

  • Controller: ESP32 or Raspberry Pi.

  • Wires: Female-to-Male Jumper Wires.

Helpful Tutorials & Resources

• GY-SPH0645LM4H_Datasheet

Frequently Asked Questions (FAQ)

1. Is this better than the blue "Sound Sensor" with the potentiometer?

   Yes, infinitely better. The blue ones only detect "Loudness" (Clap ON/OFF). This module records actual high-fidelity audio like a phone microphone.

2. Can I plug this into a standard AUX/Headphone jack?

   No. This outputs digital 1s and 0s (I2S data), not analog voltage. It cannot directly drive a speaker or amplifier input.

3. Does it work with Arduino Uno or Nano?

   No. The ATMega328 chip on the Uno is too slow and lacks the hardware I2S interface required to read the data stream.

4. Why is the volume so low on my Raspberry Pi recordings?

   Digital mics often have "DC Offset" or scaling issues in raw capture. You usually need to apply a "SoftVol" (Software Volume) plugin in your .asoundrc config to boost the gain digitally.

5. Is it waterproof?

   No. The tiny hole on top is the acoustic port. If water, oil, or flux gets in there, the mic is permanently damaged.

6. What is the effective pickup range?

   It can pick up normal conversation clearly from 2-3 meters away in a quiet room. It is quite sensitive.

7. Does it have hardware noise cancellation?

   No, it records raw audio. However, because the signal is digital and clean (no wire noise), it is much easier to apply software noise reduction later.

8. Can I use two of these at once for Stereo?

   Yes! Connect the SEL pin to GND on the first mic (Left Channel) and to 3.3V on the second mic (Right Channel). Wire them to the same I2S pins.

9. What sampling rates does it support?

   It typically works well at standard audio rates: 16kHz, 32kHz, and 44.1kHz.

10. Is this the same as the INMP441?

    They are very similar I2S mics. The SPH0645 is often preferred for Raspberry Pi because it has slightly better driver support in standard Linux kernels, but functionally they are interchangeable for most projects.

11. Can I use 5V logic from an Arduino Mega?

    No! The logic levels must be 3.3V. Using 5V on the data pins or power pin will destroy the MEMS chip.

12. Why do I hear a "Pop" sound when recording starts?

    I2S mics need a few milliseconds to wake up and stabilize their data stream. It's common practice to discard the first few samples in your code to avoid this "pop."

13. How long can the wires be?

    I2S is a high-speed digital protocol. Keep wires short—ideally under 10cm-15cm. Long wires introduce capacitance that corrupts the data, causing "clicking" sounds.

14. Does it work with Jetson Nano?

    Yes, the Jetson Nano GPIO header supports I2S, similar to the Raspberry Pi.

15. What is "DC Offset" and do I need to fix it?

    The SPH0645 output is sometimes not centered at 0. This can make the audio waveform look shifted. Simple audio processing software (like Audacity or Python code) can remove this offset easily.

16. Can I use this for FFT (Fast Fourier Transform) visualization?

    Yes, this is the perfect sensor for that. Its clean digital signal allows for very accurate frequency analysis for music reactive LEDs.

17. How do I clean the sensor if it gets dusty?

    Do not use liquid cleaners or compressed air directly into the port! You can gently brush off the PCB, but avoid the port hole.

18. What is the LRCL pin for?

    "Left/Right Clock" (also called WS or Word Select). It tells the sensor whether the current data bit belongs to the Left channel or the Right channel.

19. Does it need a driver on Raspberry Pi?

    Yes, it usually requires enabling the I2S overlay in /boot/config.txt. The generic rpi-i2s-audio or googlevoicehat-soundcard overlays often work.

20. Is the output PCM or PDM?

    It is PCM (Pulse Code Modulation) over I2S. It is not PDM (Pulse Density Modulation), so you don't need a decimation filter—the data is ready to use.