ESP32-LyraT V4.3 Getting Started Guide

This guide provides users with functional descriptions, configuration options for ESP32-LyraT V4.3 audio development board, as well as how to get started with the ESP32-LyraT board. Check section Other Versions of LyraT, if you have different version of this board.

The ESP32-LyraT is a hardware platform designed for the dual-core ESP32 audio applications, e.g., Wi-Fi or BT audio speakers, speech-based remote controllers, smart-home appliances with audio functionality(ies), etc.

What You Need

  • 1 × ESP32 LyraT V4.3 board
  • 2 x 4-ohm speakers with Dupont female jumper wires or headphones with a 3.5 mm jack
  • 2 x Micro-USB 2.0 cables, Type A to Micro B
  • 1 × PC loaded with Windows, Linux or Mac OS

If you like to start using this board right now, go directly to section Start Application Development.


The ESP32-LyraT V4.3 is an audio development board produced by Espressif built around ESP32. It is intended for audio applications, by providing hardware for audio processing and additional RAM on top of what is already onboard of the ESP32 chip. The specific hardware includes:

  • ESP32-WROVER Module
  • Audio Codec Chip
  • Dual Microphones on board
  • Headphone input
  • 2 x 3-watt Speaker output
  • Dual Auxiliary Input
  • MicroSD Card slot (1 line or 4 lines)
  • Six buttons (2 physical buttons and 4 touch buttons)
  • JTAG header
  • Integrated USB-UART Bridge Chip
  • Li-ion Battery-Charge Management

The block diagram below presents main components of the ESP32-LyraT and interconnections between components.

ESP32 LyraT block diagram

ESP32-LyraT Block Diagram


The following list and figure describe key components, interfaces and controls of the ESP32-LyraT used in this guide. This covers just what is needed now. For detailed technical documentation of this board, please refer to ESP32-LyraT V4.3 Hardware Reference and ESP32 LyraT V4.3 schematic (PDF).

The ESP32-WROVER module contains ESP32 chip to provide Wi-Fi / BT connectivity and data processing power as well as integrates 32 Mbit SPI flash and 32 Mbit PSRAM for flexible data storage.
Headphone Output

Output socket to connect headphones with a 3.5 mm stereo jack.


The socket may be used with mobile phone headsets and is compatible with OMPT standard headsets only. It does work with CTIA headsets. Please refer to Phone connector (audio) on Wikipedia.

ESP32 LyraT V4.3 Board Layout Overview

ESP32-LyraT V4.3 Board Layout Overview

Left Speaker Output
Output socket to connect 4 ohm speaker. The pins have a standard 2.54 mm / 0.1” pitch.
Right Speaker Output
Output socket to connect 4 ohm speaker. The pins have a standard 2.54 mm / 0.1” pitch.
Boot/Reset Press Keys
Boot button: holding down the Boot button and momentarily pressing the Reset button to initiate the firmware upload mode. Then you can upload firmware through the serial port. Reset button: pressing this button alone resets the system.
Audio Codec Chip
The Audio Codec Chip, ES8388, is a low power stereo audio codec with a headphone amplifier. It consists of 2-channel ADC, 2-channel DAC, microphone amplifier, headphone amplifier, digital sound effects, analog mixing and gain functions. It is interfaced with ESP32-WROVER Module over I2S and I2S buses to provide audio processing in hardware independently from the audio application.
Functions as the communication interface between a PC and the ESP32 WROVER module.
USB Power Port
Provides the power supply for the board.
Standby / Charging LEDs
The Standby green LED indicates that power has been applied to the Micro USB Port. The Charging red LED indicates that a battery connected to the Battery Socket is being charged.
Power Switch
Power on/off knob: toggling it to the left powers the board on; toggling it to the right powers the board off.
Power On LED
Red LED indicating that Power On Switch is turned on.

Start Application Development

Before powering up the ESP32-LyraT, please make sure that the board has been received in good condition with no obvious signs of damage.

Initial Setup

Prepare the board for loading of the first sample application:

  1. Connect 4-ohm speakers to the Right and Left Speaker Output. Connecting headphones to the Headphone Output is an option.
  2. Plug in the Micro-USB cables to the PC and to both USB ports of the ESP32 LyraT.
  3. The Standby LED (green) should turn on. Assuming that a battery is not connected, the Charging LED (red) will blink every couple of seconds.
  4. Toggle left the Power On Switch.
  5. The red Power On LED should turn on.

If this is what you see on the LEDs, the board should be ready for application upload. Now prepare the PC by loading and configuring development tools what is discussed in the next section.

Develop Applications

If the ESP32 LyraT is initially set up and checked, you can proceed with preparation of the development tools. Go to section Get Started, which will walk you through the following steps:

Summary of Key Changes from LyraT V4.2

  • Removed Red LED indicator light.
  • Introduced headphone jack insert detection.
  • Replaced single Power Amplifier (PA) chip with two separate chips.
  • Updated power management design of several circuits: Battery Charging, ESP32, MicorSD, Codec Chip and PA.
  • Updated electrical implementation design of several circuits: UART, Codec Chip, Left and Right Microphones, AUX Input, Headphone Output, MicroSD, Push Buttons and Automatic Upload.