ESP32 Bluetooth Speaker with MAX98357A I2S Amplifier

Uses ESP32 built-in Bluetooth to receive A2DP audio streams from smartphones and play them through speaker via MAX98357A I2S class-D amplifier. ESP32 acts as Bluetooth audio sink (like a Bluetooth speaker). Connect from phone by pairing with 'ESP32-BT-Speaker'. Audio quality: 44.1kHz, 16-bit stereo SBC codec. MAX98357A: mono I2S amplifier, 3W output into 4 Ohm speaker, powered at 3.3V or 5V. Stereo: use two MAX98357A with GAIN pin differentiating left/right channels. Volume control: rotary encoder mapped to software volume scaling. Display: I2C OLED shows track info (if AVRCP supported), volume bar, Bluetooth connection status. Auto-reconnect to last paired device on power-up. NVS stores last device info. Physical: 3W 4-ohm speaker in 3D printed enclosure, LiPo battery for portable use. Libraries: BluetoothA2DPSink (pschatzmann), I2S (built-in), U8g2.

Detailed Project Description

ESP32 Bluetooth Speaker with MAX98357A I2S Amplifier focuses on a specific hardware interface or peripheral and shows exactly how to wire it, drive it from firmware and verify it is working.

How It Works
1. The peripheral is connected to the controller using the required bus (SPI/I2C/UART/I2S/CAN/RS-485/PWM/ADC).
2. The driver library is initialised and the peripheral configured.
3. Firmware exchanges data with the peripheral and processes it (measure, decode, render, play).
4. Results are verified on a display, serial monitor or the receiving device.

Key Components and Their Role
- ESP32: dual-core Wi-Fi + Bluetooth microcontroller that runs the firmware, reads the sensors and hosts the network connection.
- OLED display (SSD1306): 128x64 I2C display used to show live readings and status.
- I2S audio interface: digital audio bus used for microphones and amplifiers.
- Li-ion battery + charger (TP4056): portable power with charge management.

Implementation Steps
1. Collect the components and study each module's datasheet (pin-out, voltage, interface).
2. Wire the circuit on a breadboard following the pin mapping; power sensors from the correct rail (3.3 V / 5 V).
3. Install Arduino IDE, BluetoothA2DPSink Library, U8g2 Library and the required libraries; flash a minimal test sketch for each module separately.
4. Write the main firmware: read sensors → process → drive outputs / send data.
5. Configure network or cloud credentials and test communication end-to-end.
6. Calibrate thresholds, add error handling (reconnect, sensor time-out) and run a long-duration test.
7. Finalise on a PCB / enclosure and document wiring, code and results.

Key Features
- Correct wiring and bus configuration
- Driver setup
- Data processing
- Verification on real hardware

Expected Output
On completion the student will have a working peripheral that is measured/driven exactly as intended.

Deliverables
- Complete source code with comments
- Circuit diagram and pin mapping
- Project report with screenshots and results
- Demonstration-ready build