ST 公司的MP34DT01是超小型低功耗全方位数字MEMS麦克风,具有容性传感元件和IC接口,单电源工作,声学过载点120 dBSPL,信噪比63dB,全方位灵敏度,灵敏度－26dBFC,PDM输出,主要用在手机,笔记本电脑,手持媒体播放器(PMP),VoIP,语音识别,数码相机和摄像机,防盗系统等.本文介绍了MP34DT01主要特性,以及采用MP34DT01和STM32 MCU的STEVAL-MKI117V1演示板主要特性,电路图,材料清单和PCB布局图.

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应用:

■ 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

图1.STEVAL-MKI117V1演示板外形图:左,顶视图,右,底视图


图2.STEVAL-MKI117V1演示板电路图(1)

图3.STEVAL-MKI117V1演示板电路图(2)
STEVAL-MKI117V1演示板材料清单:




图4.STEVAL-MKI117V1演示板PCB布局图:顶层

图5.STEVAL-MKI117V1演示板PCB布局图:底层
详情请见:
http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/DATASHEET/DM00039779.pdf
和
http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/DATA_BRIEF/DM00051593.pdf