STMicroelectronics STEVAL-MKI138V1

Overview

STEVAL-MKI138V1 from STMicroelectronics is a USB interface demonstration board built around the MP34DT01 top-port digital MEMS microphone and STM32F107RC microcontroller, serving as a PDM-to-USB audio streaming platform. It delivers 1–3.25 MHz PDM bitstreams from dual MEMS sensors, decodes them in real time, and presents itself as a plug-and-play Windows/Mac sound card without driver installation.

For engineers reviewing the STEVAL-MKI138V1 datasheet, STEVAL-MKI138V1 pinout, STEVAL-MKI138V1 application, or STEVAL-MKI138V1 equivalent, this board enables rapid validation of MEMS microphone signal chain integrity, USB audio class compliance, PDM decimation performance, and cross-platform host recognition behavior in acoustic sensing prototyping.

Technical Context

The board implements a two-stage signal path: first, the MP34DT01 generates 1-bit PDM output at up to 3.25 MHz; second, the STM32F107RC executes on-chip firmware to perform digital decimation (PDM-to-PCM conversion) and USB Audio Class 1.0 streaming. No external codec or FPGA is required.

It operates exclusively in self-powered mode via USB 2.0 (no external supply), uses full-speed USB (12 Mbps), and relies on standard OS audio stack support - no proprietary drivers. The board supports direct connection to STEVAL-MKI126Vx microphone carrier boards for multi-mic array expansion.

Key Specifications

Availability

STEVAL-MKI138V1 is available at Aetrix Electronics and suitable for acoustic sensor evaluation, USB audio subsystem validation, and MEMS microphone algorithm development requiring stable component supply and documented reference firmware.

Supply support for STEVAL-MKI138V1 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

STMicroelectronics is a global semiconductor leader headquartered in Geneva, designing and manufacturing microcontrollers, sensors, power ICs, and analog/mixed-signal devices for industrial, automotive, and consumer applications.

This board belongs to ST's STEVAL (ST Evaluation) product line, engineered specifically to accelerate customer adoption of ST's MEMS microphones and STM32 MCUs in audio capture and edge processing use cases.

FAQ

Does STEVAL-MKI138V1 require custom drivers on Windows or macOS?

No. The board implements USB Audio Class 1.0, so it is recognized natively as a stereo input device on Windows 7+, macOS 10.10+, and Linux with ALSA. No INF files, kexts, or SDKs are needed for basic audio capture functionality.

Can STEVAL-MKI138V1 stream audio at sample rates other than 48 kHz?

No. Firmware is fixed to 48 kHz PCM output. The STM32F107RC decimation logic and USB descriptor are configured exclusively for 16-bit, 48 kHz, stereo streaming. Rate switching or resampling is not supported in the shipped firmware.

Is the MP34DT01 microphone replaceable with another PDM MEMS device?

No. The board layout, firmware timing, and GPIO routing are optimized for MP34DT01's specific PDM clock/data phase relationship and startup sequence. Substitution with other PDM mics (e.g., INMP441 or IM69D130) is not supported without hardware and firmware redesign.

What software tools are recommended for configuring or reprogramming STEVAL-MKI138V1?

APWorkbench is the official ST tool for configuring microphone parameters and generating custom firmware images. For low-level development, STSW-STM32068 (STM32F107 USB Audio firmware package) and STM32CubeMX are required to rebuild or modify the USB audio stack and PDM interface drivers.