Adafruit PDM MEMS Microphone Breakout

Adafruit PDM MEMS Microphone Breakout is based on an STMicroelectronics MP34DTx MEMS Audio Microphone. The MP34DTx MEMS Microphones are capable of detecting acoustic waves and are manufactured using a specialized silicon micromachining process dedicated to producing audio sensors. The IC interface uses a CMOS process that allows designing a dedicated circuit able to provide a digital signal externally in PDM form. 

The PDM has a very simple digital interface but it's not PWM or I2S, so the chip has to have a PDM interface. Most 32-bit processors available do. PDM is a little like 1-bit PWM. Clock the mic with a 1-3MHz clock rate, and on the data line to get a square wave out that syncs with the clock. The data line with be 0 or 1 logic output, with the square wave creating a density that, when averaged, will result in the analog value out.


  • MP34DTx MEMS Audio Microphone
  • 1.8V to 3.3V input voltage range
  • 1MHz to 3.25MHz clock rate
  • 0.6mA current draw
  • 61dB signal-to-noise ratio
  • -26dBFS sensitivity
  • 14.0mm x 12.8mm x 2.8mm PCB; 0.5g


Board Layout

Adafruit PDM MEMS Microphone Breakout
Published: 2018-02-23 | Updated: 2022-08-15