Project Hub /Audio Displays & Interactive Media/LED Matrix & Cube Displays/DIY ESP32 Voice Recorder with SD Card and OLED Display

Intermediate

ESP32

Project Specific

3 – 6 Hours

Partial Kit

DIY ESP32 Voice Recorder with SD Card and OLED Display

Build a compact portable digital voice recorder using an ESP32-S2-based IndusBoard Coin, an INMP441 I2S MEMS microphone, an OLED display, and a microSD card.

Originally published on ElectronicsForU

View original tutorial

Parts You'll Need

This project is sourced from another site, not written by us — this list is our best match of their components against what we stock, not a verified bill of materials. Always check the original blog (linked above) for the actual parts list before buying.

0.96 Inch I2C/IIC 4pin OLED Display Module White Rs. 349.00
Microphone module - Analog Sound Sensor Module for Arduino Rs. 63.00
400 Points Mini Solderless Prototype PCB Breadboard High Quality Rs. 89.00
MB102 Adjustable Breadboard Power Supply Module (3.3V & 5V) for Arduino & Raspberry Pi Rs. 139.00
Jumper Wire 10 Pin Male To Male 20cm Rs. 45.00
Jumper Wire 10 Pin Male To Female 20cm Rs. 45.00

Selected: Rs. 0.00

We don't carry yet: Battery (generic / unspecified)
Other Dev Board (Indusboard / Maixduino / misc)
SD Card Module

Browse all components

How It Works

This portable digital voice recorder system operates by coordinating audio acquisition, local data storage, visual feedback, and power management through the ESP32-based IndusBoardV2 microcontroller. When the system is active, the INMP441 I2S MEMS microphone captures surrounding acoustic waves and converts them into digital audio data streams using the inter-IC sound (I2S) protocol, which allows for efficient, low-jitter serial transfer of high-fidelity digital audio directly to the microcontroller. The IndusBoardV2 processes these incoming audio blocks and streams them over a secondary interface to the SD card reader module, where the data is written and saved persistently onto a standard microSD card as raw or encoded audio files. Concurrently, the system drives an SSD1306 OLED 128x64 display via the I2C communication bus to provide real-time visual status updates, such as recording indicators, file information, or system readiness states. The entire standalone circuit is powered by a rechargeable 3.3V 1500mAh battery, delivering a stable operating voltage directly suited for the low-power logic levels of the microcontroller, display, and digital sensors. The firmware, compiled and uploaded via the Arduino IDE using the U8g2 display library, standard SD library, and built-in ESP32 I2S drivers, continuously manages the balance between reading audio data, writing blocks to storage, refreshing the graphical user interface, and monitoring system execution.

Why Build This

Design and deploy an embedded digital signal acquisition system capable of real-time audio sampling, protocol-based sensor communication, and persistent file writing for field research or automated data logging.

Gain practical undergraduate-level experience integrating multiple communication interfaces—specifically I2S for high-speed digital audio streaming and I2C for peripheral display control—within a single resource-constrained microcontroller environment.

Construct a completely portable, battery-powered embedded gadget that demonstrates power management, user interface rendering, and mass storage handling in a compact physical footprint.

Real-World Application

Interviews, field research, wildlife monitoring, covert audio capture, and machine sound analysis.

Skills You'll Learn

I2S digital audio communication

I2C display interfacing

SPI or SD card file system management

embedded power management

real-time sensor data acquisition

graphical user interface rendering

Safety Precautions

No specific precautions noted for this build — always follow general electronics safety practices.

Technology Tags

ESP32-S2

INDUSBOARD COIN

INMP441

I2S MEMS MICROPHONE

OLED DISPLAY

MICROSD CARD

AUDIO RECORDING

WAV FILE

SPI

I2C

ARDUINO IDE

Frequently Asked Questions

Can I use any standard microphone with the IndusBoardV2 for this project?

No, this project specifically requires an I2S digital MEMS microphone like the INMP441. Traditional analog microphones output a varying voltage that requires an Analog-to-Digital Converter, whereas the INMP441 outputs direct digital audio packets compatible with the ESP32's hardware I2S peripheral.

How is the audio data stored on the microSD card?

The ESP32 uses the standard SD card library to interface with the SD card reader module, allowing the microcontroller to create, write, and manage files directly on a formatted microSD card inserted into the module.

What software environment do I need to program the IndusBoardV2?

You will need the Arduino IDE installed on your computer, along with the ESP32 board package, the U8g2 graphics library for the OLED display, the SD library, and the ESP32 I2S driver to handle the audio pipeline.

Gallery

This page is part of Kitkraft's Project Hub — a curated collection of electronics & robotics projects gathered from the maker community to help students and hobbyists discover and learn to build. Kitkraft does not claim authorship of the original project, and makes no representation as to the accuracy, completeness or safety of third-party source material. The summary and "How It Works" explanation above are AI-generated, rewritten with reference to the original tutorial — not a reproduction of it. Full credit and a direct link to the original source are provided above. If you're the original creator and have a concern about how your work is represented here, please contact us and we'll address it promptly.

Kitkraft Project Hub — curated from the maker community, credited at the source.

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