March 2013

DocID024106 Rev 1

1/13

AN4227

Application note

Audio hub demonstration kit supporting the MP45DT02,

MP34DB01, and MP34DT01 microphones

Introduction

This document provides a brief description of the audio hub demonstration board STEVAL-

APWorkbench software tool.

The purpose of this board is twofold:

1.

It can be used as an STSmartVoice interface. In combination with this board

(STEVAL-MKI126Vx), it manages the signal coming from the onboard microphones.

The STSmartVoice board hosts up to six microphones and the STA321MPL

format. (For additional details, please refer to AN4146 “STSmartVoice demonstration

the STM32F107RC microcontroller, is able to program the STA321MPL device via the

captured by the microphones. Multiple features for using the microphones on the

STSmartVoice demonstration board are listed and accessible thanks to the

APWorkbench software tool.

2.

It can be used as a USB sound card. As shown in Figure 1, the audio hub board hosts

either the MP45DT02 or MP34DT01 (top-port digital microphones) and the MP34DB01

which is a bottom-port digital microphone. The board is able to host both types of

microphones as shown below. The task of the STM32 microcontroller is to decode the

PDM signals coming from the microphones and stream the audio via the USB.

Figure 1. STEVAL-MKI138V1

Entire board (top and bottom views)

Microphone section (zoom)

MP45DT02

MP34DT01

MP34DB01

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