Bluetooth Speaker using ESP32 and MAX98357 I2S Digital Amplifier
Table of Contents
Bluetooth Speaker using ESP32:
Bluetooth Speaker using ESP32 and MAX98357 I2S Digital Amplifier– In my free time, I often go to the terrace of my house and sit there. I frequently either listen to songs or watch a movie on Netflix. However, I can’t fully enjoy it because the sound from my cell phone is not loud enough. I also don’t prefer using headphones because they could cause ear infections.
I already have a powerful amplifier system, but I can’t take it to the terrace, and I can’t take it camping either.
So, I thought why not to make myself a very simple Bluetooth Speaker. Because I already have the required components like the ESP32 WiFi + Bluetooth module and as you know it supports I2S Audio Outputs.
I2S stands for “Inter-IC Sound” or “Integrated Interchip Sound,” is a digital audio interface standard used for transmitting digital audio data between integrated circuits (ICs) in electronic devices. It is commonly used in applications such as audio codecs, digital signal processors, and microcontrollers for processing and transmitting audio signals.
I also have this digital amplifier based on the MAX98357 I2S Class D amplifier and this 3W and 8Ω speaker.
So, for this project you only need these three components an ESP32 board, an amplifier module, and a speaker. So, without any further delay let’s get started!!!
Amazon Links:
ESP32 WiFi + Bluetooth Module(Recommended)
*Disclosure: These are affiliate links. As an Amazon Associate I earn from qualifying purchases.
MAX98357 I2S Amplifier Module:
This I2S digital amplifier is based on the MAX98357 I2S Class D amplifier module, offering exceptional compatibility with microcontrollers equipped with I2S audio outputs, such as the ESP32 WiFi + Bluetooth Module. It can be used in projects like IoT nodes, smart home devices, Bluetooth audio players, and so on.
It features a PH2.0 connector and stamped holes for seamless speaker connections, enhancing its adaptability and user-friendliness.
The module supports 3.3V-5V power supply. And it can output over 2.5W of power when driven by 5V and a 4Ω speaker. Besides, it allows users to set different modes (off, left channel, right channel, and mixed) by changing the resistance on the SD port. The product defaults to be mixed mode. Featuring a small size, this I2S amplifier comes with stamp holes that enable it to be directly plugged into or mounted on a PCB and breadboard. Also, it is designed with PH2.0 and stamp holes for connecting speakers, flexible and convenient to use.
These are some of the Features and Specifications:
Features
- MAX98357 I2S digital Class D amplifier, power >2.5W
- 3.3V~5V voltage power supply
- Switchable sound channel
- Adjustable gain
- Stamp holes design, support SMT and DIP
- Two ways to connect a speaker: PH2.0 and stamp holes
Specification
- MCU: MAX98357A
- Operating Voltage: DC 3.3V~5V
- Output Power: 8Ω 1.8W / 4Ω 2.5W (at 12db)
- Output Channel: single channel
- Communication Interface: I2S interface
- Operating Temperature: -40℃ – ＋80℃
- Storage Temperature: -40℃ – ＋80℃
- Dimension (Without Packaging): 18mm × 18mm/ 0.059 × 0.059
Application
- Bluetooth Audio Player
- IoT Node Audio Player
- Smart Home Voice Interaction
- Robotic Device Audio Player
Board Overview:
| in | Function | Remark |
| SPK- | Speaker negative | 4Ω/8Ω ＜3W |
| VCC | Power input | DC 3.3V-5V |
| GND | Ground | |
| NC | Not connected pin | |
| SD | Turn off amplifier, adjust sound channel | Refer to 4.1.2(SD Mode Description) |
| GAIN | Adjust amplifier gain | Default to 9dB/Refer to 4.1.1 Gain Control Description |
| SPK+ | Speaker positive | 4Ω/8Ω ＜3W |
| DIN | Digital input signal | |
| BCLK | Bit clock input | Bit Clock Input |
| LRC | Frame clock | Left/right clock of I2S and LJ mode. Synchronized clock in TDM mode |
What is I2S?
I2S, which stands for “Inter-IC Sound” or “Integrated Interchip Sound,” is a digital audio interface standard used for transmitting digital audio data between integrated circuits (ICs) in electronic devices. It is commonly used in applications such as audio codecs, digital signal processors, and microcontrollers for processing and transmitting audio signals.
I2S is characterized by its separate data and clock lines, making it a straightforward and efficient method for transferring high-quality audio data. The standard typically uses three signal lines:
- Serial Data (SD): This line carries the audio data in a serial bitstream format. It can be either left-justified, right-justified, or in I2S standard format, depending on the configuration.
- Word Select (WS) or Frame Sync (FS): This line indicates the start of a new audio data word and helps the receiver distinguish between left and right audio channels.
- Serial Clock (SCK): This line provides the clock signal that dictates the timing for the data transmission.
I2S is widely used in audio applications, such as connecting digital audio sources (like microphones and digital audio players) to audio processing components (like digital-to-analog converters and amplifiers). It enables high-fidelity audio transmission and is often found in consumer electronics, audio interfaces, and professional audio equipment.
3W and 8Ω Speaker:
It’s a 3W and 8Ω Speakers with JST PH2.0 interface which nice plugs into the PH2.0 connector. It is perfect for any DIY audio project which requires an 8 ohm impedance and 3W power. And these are some of the specifications.
SPECIFICATION
Power: 3 W
Resistance: 8 Ω
Line length: 42 cm
Distortion: < 10%
Product size: 70 * 30 * 16 mm/2.76 * 1.18 * 0.63 inches
The pitch of screws: 24 * 63 mm/ 0.94 * 2.5 inches
Weight: 24 g
Bluetooth Speaker Circuit Diagram:
Connect the VCC and GND pins of the MAX98357 amplifier module to the ESP32 3.3V and GND pins.
Connect LRC pin of the MAX98357 amplifier module to the GPIO26 on the ESP32.
Connect BCLK Pin to the GPIO27 pin on the ESP32.
Connect DIN to GPIO25.
Connect your speaker + and – wires to the amplifier module SPK+ AND SPK- pins. In my case, I am using the PH2.0 connector.
ESP32 Board installation in the Arduino IDE:
If this is your first time using an ESP32 board then first of all, you will need to install it in the Arduino IDE and for this you can read my article on the ESP32. It doesn’t matter if you are using another version of the ESP32 board. The installation is the same.
Once your ESP32 board is installed and its available in the Arduino IDE. Next, you will need to add ESP32-A2DP-MAIN library in the Arduino IDE.
After downloading the above library, simply go to the Sketch Menu, then to Include Library, and click on the Add .Zip library.
Browse to the location and select this library and press the open button.
You will see a message that the library is added in the Arduino IDE. Now, finally, you can copy the following code and upload it into your ESP32 board.
Bluetooth Speaker Programming:
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#include "BluetoothA2DPSink.h" BluetoothA2DPSink a2dp_sink; void setup() { i2s_pin_config_t my_pin_config = { .bck_io_num = 27, ////BCLK .ws_io_num = 26, ////LRC pin .data_out_num = 25, ///Din pin .data_in_num = I2S_PIN_NO_CHANGE }; a2dp_sink.set_pin_config(my_pin_config); a2dp_sink.start("MyMusic"); } void loop() { } |
Bluetooth Speaker Testing:
To power this Bluetooth speaker system you can use a single cell Lithium-ion battery, you can also use a power bank which you can connect to the Micro USB port of the EPS32 board. But in my case, I am going to use my created 4S lithium Ion battery pack and I am not worried about the voltage, as my ESP32 development board already has a 5V regulator based on the 7805 voltage regulator. Anyway, I powered up my Bluetooth Speaker system using a 4S lithium Ion battery.
Now, all I need is to connect my cell phone to the Bluetooth Speaker and that’s it.
I am quite impressed with the sound quality and the wireless range of my DIY Bluetooth Speaker is around 8 meters which is more than enough for me. So, that’s all for now.
