Adafruit
Adafruit PDM MEMS Microphone Breakout
The Adafruit PDM MEMS Microphone Breakout provides a digital audio input using Pulse Density Modulation (PDM) — a common interface in commercial products tha...
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The Adafruit PDM MEMS Microphone Breakout provides a digital audio input using Pulse Density Modulation (PDM) — a common interface in commercial products that's distinct from both analogue and I2S microphones. It's ideal for microcontrollers without analogue inputs, and most modern 32-bit processors include a hardware PDM peripheral.
PDM works by clocking the microphone at 1–3 MHz and reading a 1-bit digital output whose pulse density represents the analogue audio signal. When filtered and decimated, this produces clean audio samples. Many platforms (nRF52, RP2040, SAMD51) handle this in hardware with library support, while others may require manual filtering.
Key Features
- PDM Digital Output – 1-bit pulse density modulation, not analogue or I2S
- MEMS Microphone – Compact, high-quality digital microphone element
- 1–3 MHz Clock Rate – Standard PDM clocking compatible with most 32-bit MCUs
- No Analogue Input Required – Fully digital interface, no ADC needed
- Breadboard Friendly – Includes header strip for easy prototyping
Integration Approaches
- Hardware PDM Peripheral – Best option: the MCU handles clocking, filtering, and decimation automatically (nRF52, RP2040, SAMD51, etc.)
- Hardware Peripheral + Manual Filtering – The MCU provides raw PDM data; you apply decimation and filtering in software
- Analogue Filter Hack – Generate the clock externally, apply an analogue low-pass filter on the data line, and read the result as an analogue value
Ideal For
- Voice and audio capture on digital-only microcontrollers
- Sound-reactive projects and audio level detection
- Adding microphone input to boards without analogue pins
Package Contents
- 1× PDM MEMS Microphone Breakout (assembled and tested)
- 1× Header strip for breadboard use
Resources
- PDM Microphone Learn Guide (wiring, schematics, example code, datasheet)
Jargon buster
Plain-language definitions for the technical terms used above.
- ADC
- An analogue-to-digital converter reads a changing voltage and turns it into a number the microcontroller can use. It matters when connecting analogue sensors such as light, sound, or variable-resistor sensors.
- AVR
- AVR is a family of 8-bit microcontrollers (made by Microchip, formerly Atmel) used in many classic Arduino-style boards such as the Uno and Nano. They are widely supported but older, which can be a limit for memory- or speed-intensive tasks.
- breakout
- A breakout board carries a small or fine-pitched component and brings its connections out to standard, breadboard- and header-friendly pins. Describing a part as a breakout means it can be wired into a project without soldering directly to the component's tiny contacts.
- I2S
- I2S is a digital audio interface used to send sound data between chips, such as from a microcontroller to an audio amplifier or DAC. It matters if your project needs cleaner digital audio output than a basic buzzer or PWM signal can provide.
- MEMS microphone
- A tiny microphone made using micro-electromechanical systems, the same style of miniature manufacturing used in many phone sensors. It lets the board detect sound without needing an external microphone, which is useful for noise-reactive projects and simple audio input.
- RP2040
- The RP2040 is a dual-core Arm Cortex-M0+ microcontroller chip from Raspberry Pi, used on many maker boards and offering programmable I/O, multiple GPIO pins and reasonable processing speed. Code and accessories built for that chip should work where RP2040 compatibility is listed, though demanding tasks such as reading a camera can require careful pin allocation and timing.
- SAMD51
- A family of 32-bit ARM Cortex-M4 microcontroller chips from Microchip, often used to run the main program on a development board. When a board is built around a SAMD51 it generally offers more speed and memory than basic 8-bit microcontrollers, which helps with demanding tasks such as graphics, audio or fast data handling.
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