How to Play PCM Through I2S on ESP32

Learn how to effectively play PCM audio through I2S on an ESP32 board with step-by-step instructions and working code samples.
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How to Play PCM Through I2S on ESP32: A Complete Guide

If you're an electronics enthusiast or a developer working with the ESP32-WROOM-32D board and MAX98357A I2S board, you might find yourself in a situation where you need to play PCM audio. This task can be a bit tricky, especially when dealing with audio formats like 8kHz 8bit PCM. In this guide, I will walk you through the process of successfully playing PCM audio using the I2S protocol.

The Context

You have a constant buffer for PCM audio declared in a header file, but despite your efforts with multiple code snippets, you're not hearing any sound from the speaker. Before diving into the code, let’s clarify a few important aspects of the I2S configuration.

Why I2S?

I2S, or Inter-IC Sound, is a serial bus interface for connecting digital audio devices. It’s commonly used to connect audio codecs and digital-to-analog converters (DACs). The ESP32 supports I2S natively, making it a versatile choice for audio projects.

Setting Up Your Environment

Before you start writing code, ensure you have the necessary libraries installed in your Arduino IDE:

ESP32 Board Support - Make sure you have the ESP32 board definitions installed in your Arduino IDE.

I2S Library - This library facilitates easy communication over the I2S bus.

The Problem with Your Code

Your initial attempts contained two main pitfalls:

The MAX98357A chip typically requires a minimum of 16-bit audio to function properly.

The configuration settings related to pin assignments, sample rate, and bit depth must match the requirements of both the ESP32 and the I2S audio device.

Step-by-Step Solution

Working Code Sample

Here, I will provide a fully functional code sample that plays an audio buffer using I2S. We'll start with a sample that requires 16-bit audio.

Setup Code

[[See Video to Reveal this Text or Code Snippet]]

Adapting for 8-bit PCM Audio

If you want to play 8-bit PCM audio, you'll need to remap the byte values to the 16-bit range:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

Playing PCM audio through I2S on the ESP32 can be challenging but entirely doable with the right configuration and code setup. By understanding the requirements for your hardware and properly adjusting your code, you can effectively bring your audio projects to life.

Feel free to experiment with different audio files and settings to see what works best for your project.

Happy coding!

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