Espressif ESP32-WROVER
Ultra-Compact Keychain MP3 Player
Overview
An ultra-compact, keychain-sized portable MP3 player powered by a microcontroller, featuring MicroSD storage, an audio codec with a 3.5mm headphone jack, a tiny display, and USB-C rechargeable LiPo battery power.
Aiman RosmanSystem architecture
MCU
POWER
MODULE
DISPLAY
ACTUATOR
- POWER → MCUPowerSupplies regulated operating voltage to the MCU
- POWER → DISPLAYPowerSupplies power to the OLED display
- POWER → AUDIO_DACPowerSupplies power to the audio DAC
- POWER → AMPPowerSupplies power to the headphone amplifier
- MCU → STORAGESPIReads MP3 files from the MicroSD card
- MCU → DISPLAYI2CSends graphical data and commands to the OLED screen
- MCU → AUDIO_DACI2STransfers digital audio stream via I2S protocol
- AUDIO_DAC → AMPGPIORoutes analog audio output from DAC into headphone amplifier input
Bill of materials
| Part number | Type | Component | Manufacturer | Package | Qty | Datasheet | Match |
|---|---|---|---|---|---|---|---|
| ESP32-WROVER | MCU | Espressif ESP32-WROVER Central processing unit for MP3 decoding, file system management, and peripheral control | Espressif Systems | MODULE_18X31.4MM_SM | 1 | Matched | |
5 alternatives consideredAI verified | |||||||
| RT9013-33 | POWER | TP4056 & RT9013 Manages USB-C LiPo battery charging and provides regulated 3.3V power rails | RICHTEK | — | 1 | Matched | |
2 alternatives consideredAI verified | |||||||
| 104031-0811 | MODULE | MicroSD Card Socket Stores MP3 audio files and user playlists via SPI/SDMMC interface | Molex | Reel | 1 | Matched | |
| SSD1306-470MT | DISPLAY | 0.96-inch OLED Display (SSD1306) Displays playback status, track names, and user navigation menus | Shenzhen Lantu Micro Electric Technology Co., Ltd. | 18.54 mm x 15.24 mm | 1 | Matched | |
3 alternatives consideredAI verified | |||||||
| PCM5102A | MODULE | Texas Instruments PCM5102A Converts digital I2S audio stream from MCU into high-fidelity analog signals | Texas Instruments | Tube Alternate Packaging | 1 | Matched | |
2 alternatives consideredAI verified | |||||||
| MAX97220AETE+ | ACTUATOR | MAX97220A Drives the 3.5mm headphone jack with pop-less stereo amplification | Maxim Integrated | Tube Alternate Packaging | 1 | Matched | |
1 alternatives consideredAI verified | |||||||
Build guide
5-7 hoursAdvanced
1
Procurement & Preparation
- Source and verify all required BOM components including the ESP32-WROVER, TP4056 & RT9013 power management ICs, MicroSD card socket, 0.96-inch SSD1306 OLED display, PCM5102A audio DAC, and MAX97220A headphone amplifier.
- Inspect the custom keychain-sized printed circuit board (PCB) for trace defects, shorts, or misaligned silkscreen markings, and prepare a 3.7V LiPo battery along with a 3.5mm headphone jack.
2
Hardware Assembly & Wiring
- Apply solder paste to the power management section and solder the TP4056 USB-C charging circuit and RT9013-33 LDO regulator to establish the 3.3V power rails for the entire system.
- Solder the Espressif ESP32-WROVER module onto the mainboard, ensuring all castellated pads make proper contact with the PCB ground and GPIO pads.
- Wire and solder the MicroSD Card Socket to the MCU using SPI interface lines (MISO, MOSI, SCK, CS) alongside 3.3V power and GND connections.
- Connect the 0.96-inch OLED display to the MCU via the I2C bus (SDA, SCL) and route the 3.3V power and GND rails.
- Integrate the Texas Instruments PCM5102A audio DAC, connecting it to the MCU through I2S signals (BCLK, LRCK, DATA), and wire its analog outputs to the MAX97220A headphone amplifier driving the 3.5mm jack.
3
Firmware Setup
- Connect the ESP32-WROVER module to a development computer via a USB-to-UART bridge adapter and configure the software development environment.
- Compile and flash the MP3 player firmware, which includes the audio decoding library, FAT filesystem driver for the MicroSD card, SSD1306 display menu logic, and I2S audio output routines.
4
Testing & Calibration
- Connect a 5V USB-C power source to the TP4056 charging circuit and verify proper battery charging behavior and that the RT9013 outputs a steady 3.3V rail.
- Insert a MicroSD card loaded with sample MP3 files into the socket and test file system initialization, directory navigation via the OLED display, and playback functionality.
- Plug standard headphones into the 3.5mm jack to test stereo audio output quality through the PCM5102A DAC and MAX97220A amplifier, checking for pops, clicks, or channel imbalances.
Document
Ultra-Compact Keychain MP3 Player
An ultra-compact, keychain-sized portable MP3 player powered by a microcontroller, featuring MicroSD storage, an audio codec with a 3.5mm headphone jack, a tiny display, and USB-C rechargeable LiPo battery power.
Design Overview
| Item | Details |
|---|---|
| Product Type | Portable MP3 Player |
| Key Functions | MP3 audio playback, MicroSD storage interface, Compact OLED/LCD display navigation, USB-C battery charging |
| Power Source | Rechargeable LiPo Battery with USB-C Charging |
| Connectivity | 3.5mm Headphone Jack |
| Size | Ultra-compact keychain size |
| Environment | Casual daily listening (commute, office) |
| Difficulty | Advanced |
| Est. Time | 5-7 hours |
System Architecture
Power Topology: USB-C input charges the LiPo battery via a TP4056 linear charger IC. A low-dropout regulator (RT9013) steps down the battery/USB voltage to provide a stable 3.3V rail for the ESP32 MCU, display, storage, DAC, and headphone amplifier.
Module List
| Module ID | Type | Name | Function | Voltage |
|---|---|---|---|---|
| MCU | MCU | Espressif ESP32-WROVER | Central processing unit for MP3 decoding, file system management, and peripheral control | 3.3V |
| POWER | POWER | TP4056 & RT9013 | Manages USB-C LiPo battery charging and provides regulated 3.3V power rails | 3.7V/5V |
| STORAGE | MODULE | MicroSD Card Socket | Stores MP3 audio files and user playlists via SPI/SDMMC interface | 3.3V |
| DISPLAY | DISPLAY | 0.96-inch OLED Display (SSD1306) | Displays playback status, track names, and user navigation menus | 3.3V |
| AUDIO_DAC | MODULE | Texas Instruments PCM5102A | Converts digital I2S audio stream from MCU into high-fidelity analog signals | 3.3V |
| AMP | ACTUATOR | MAX97220A | Drives the 3.5mm headphone jack with pop-less stereo amplification | 3.3V |
Key Components
6/6 modules matched to real parts. See the BOM tab for the full component table.
Espressif ESP32-WROVER (ESP32-WROVER)
Candidate 1 (ESP32-WROVER) matches the primary MPN exactly and is manufactured by Espressif Systems.
TP4056 & RT9013 (RT9013-33)
Candidate 2 has the exact MPN match 'RT9013-33' from manufacturer RICHTEK, including the correct 3.3V output suffix requ
Build Summary
- Difficulty: Advanced
- Estimated time: 5-7 hours
- Tools required: Digital Multimeter, Reflow Hot Air Station, Soldering Iron, Solder Paste Syringe, Tweezers, Magnifying Glass
See the Build tab for the full step-by-step assembly guide.
Generated by YuanQi AI Design System · Query: Small portable MP3 player with a microcontroller, audio solution (codec/DAC), storage interface (MicroSD), and a compact display (OLED/LCD).