ST 公司的MP34DT01是超小型低功耗全方位數(shù)字MEMS麥克風(fēng),具有容性傳感元件和IC接口,單電源工作,聲學(xué)過載點(diǎn)120 dBSPL,信噪比63dB,全方位靈敏度,靈敏度-26dBFC,PDM輸出,主要用在手機(jī),筆記本電腦,手持媒體播放器(PMP),VoIP,語音識別,數(shù)碼相機(jī)和攝像機(jī),防盜系統(tǒng)等.本文介紹了MP34DT01主要特性,以及采用MP34DT01和STM32 MCU的STEVAL-MKI117V1演示板主要特性,電路圖,材料清單和PCB布局圖.

The MP34DT01 is an ultra-compact, low-power,omnidirectional, digital MEMS microphone built with a capacitive sensing element and an IC interface.

The sensing element, capable of detecting acoustic waves, is manufactured using a specialized silicon micromachining process dedicated to produce audio sensors.

The IC interface is manufactured using a CMOS process that allows designing a dedicated circuit able to provide a digital signal externally in PDM format.

The MP34DT01 has an acoustic overload point of 120 dBSPL with a 63 dB signal-to-noise ratio and –26 dBFS sensitivity.

The MP34DT01 is available in a top-port, SMDcompliant, EMI-shielded package and is guaranteed to operate over an extended temperature range from -30℃ to +70℃.

MP34DT01主要特性:

■ Single supply voltage

■ Low power consumption

■ 120 dBSPL acoustic overload point

■ 63 dB signal-to-noise ratio

■ Omnidirectional sensitivity

■ –26 dBFS sensitivity

■ PDM output

■ HCLGA package

– Top-port design

SMD-compliant

– EMI-shielded

– ECOPACK® , RoHS, and “Green” compliant

MP34DT01應(yīng)用:

■ Mobile terminals

■ Laptop and notebook computers

■ Portable media players

■ VoIP

■ Speech recognition

■ A/V eLearning devices

■ Gaming and virtual reality input devices

■ Digital still and video cameras

■ Antitheft systems

MEMS microphone demonstration board based on the MP34DT01 and STM32

The purpose of the STEVAL-MKI117V1 demonstration board is to provide an example of the decoding and streaming of digital MEMS microphone outputs.

The STEVAL-MKI117V1 demonstration board hosts the MP34DT01 (bottom-port digital microphone), working as a sensor, and the STM32F107RC microcontroller, working as an audio decoder.

These microphones are analog-to-digital transducers. They are able to sense sound pressure and convert this signal into a digital signal using the PDM technique.

The STM32 microcontroller decodes the PDM signal coming from the microphones and streams the audio via the USB.

The STEVAL-MKI117V1 demonstration board is a sound card automatically recognized by the PC as an audio device. Connection is made through a USB cable which also supplies the board and then streams the collected audio.

STEVAL-MKI117V1演示板主要特性:

■ Powered and connected to PC through USB

■ Sound card automatically recognized by the PC as an audio device

■ The onboard microphones are digital MEMS devices

■ MEMS microphones provide a high frequency data stream (1 to 3.25 MHz) of 1-bit digital samples (PDM technique)

■ Audio collected from the microphones is sent to the PC through the USB

■ LED status indicator

■ RoHS compliant

圖1.STEVAL-MKI117V1演示板外形圖:左,頂視圖,右,底視圖

圖2.STEVAL-MKI117V1演示板電路圖(1)

圖3.STEVAL-MKI117V1演示板電路圖(2)

STEVAL-MKI117V1演示板材料清單:

圖4.STEVAL-MKI117V1演示板PCB布局圖:頂層

圖5.STEVAL-MKI117V1演示板PCB布局圖:底層