What is it

Amped-ESP32 combines ubiquitous ESP32 with a PCM5100 HiFi DAC teamed up with a highly efficient TPA3110D2 D-class amplifier (replaced by TPA3128 starting Rev H). It brings all the best from the HiFi-ESP32 model and adds an onboard amp to form a complete solution that can be paired with speakers directly. It uses an external power source to feed hungry amps and the host MCU using an onboard drop-down converter. It has similar power capabilities to the Louder-ESP32 model, but it is much simpler to use since it only needs a valid I2S signal to operate, so a simple book example code will do it

Motivation

I spent the last few years developing different solutions based on ESP devices. It all started with ESP8266, where CPU power is not really sufficient to do real-time decoding, so you're limited to a rather simple ding-dong business. Then ESP32 came, bringing two much more capable cores, so you have a powerhouse to handle communication and decoding at the same time. Perhaps most importantly, it also came with SPIRAM, so you can do decent buffering (essential for streamed content). Now, new ESP32 C-Series and S-Series chips are entering the market, and their potential is mostly unrealized as of today

I created ESP32 Audio docks and subsequently development boards, to be able to quickly prototype for the whole range of ESP8266 and ESP32 chips, starting with the simplest finger-sized toys and going all the way up to full-sized speakers.

Recently I went a rabbit hole of Home Assistant integrations and discovered different ways ESP32 with a decent DAC can be integrated into complex Home setups.

Features

	HiFi-ESP32	HiFi-ESP32S3	Loud-ESP32	Loud-ESP32S3	Louder-ESP32	Louder-ESP32S3	Amped-ESP32	Amped-ESP32S3
MCU	ESP32-WROVER-N8R8	ESP32-S3-WROOM-N8R8	ESP32-WROVER-N8R8	ESP32-S3-WROOM-N8R8	ESP32-WROVER-N8R8	ESP32-S3-WROOM-N8R8	ESP32-WROVER-N8R8	ESP32-S3-WROOM-N8R8
DAC	PCM5100A 32-bit Stereo DAC -100 dB typical noise level	PCM5100A 32-bit Stereo DAC -100 dB typical noise level	Dual I2S DAC (MAX98357) with built-in D-Class amp	Dual I2S DAC (MAX98357) with built-in D-Class amp	Stereo I2S DAC (TAS5805M) with built-in D-Class amp	Stereo I2S DAC (TAS5805M) with built-in D-Class amp	PCM5100A 32-bit Stereo DAC working with TPA3128D2 D-class amp	PCM5100A 32-bit Stereo DAC working with TPA3128D2 D-class amp
Output (4Ω)	Non-amplified stereo output, 2.1V RMS	Non-amplified stereo output, 2.1V RMS	2x 5W	2x 5W	2x 32W (4Ω, 1% THD+N)	2x 32W (4Ω, 1% THD+N)	Line-level putput, 2.1V RMS, and 2x 40W (4Ω, 1% THD+N) at 20V 1x 60W (3Ω, 1% THD+N) at 20V (bridged)	Line-level putput, 2.1V RMS, and 2x 40W (4Ω, 1% THD+N) at 20V 1x 60W (3Ω, 1% THD+N) at 20V (bridged)
Output (8Ω)	Non-amplified stereo output	Non-amplified stereo output	2x 3W	2x 3W	2x 22W (8Ω, 1% THD+N)	2x 22W (8Ω, 1% THD+N)	2x 22W (8Ω, 1% THD+N) at 20V	2x 22W (8Ω, 1% THD+N) at 20V
PSRAM	8MB PSRAM (4MB usable) over 40MHz SPI	8MB PSRAM over 80MHz QSPI	8MB PSRAM (4MB usable) over 40MHz SPI	8MB PSRAM over 80MHz QSPI	8MB PSRAM (4MB usable) over 40MHz SPI	8MB PSRAM over 80MHz QSPI	8MB PSRAM (4MB usable) over 40MHz SPI	8MB PSRAM over 80MHz QSPI
Power	5V over USB-C, 2x LP5907 3.3 V Ultra-Low-Noise LDO for analog section	5V over USB-C, 2x LP5907 3.3 V Ultra-Low-Noise LDO for analog section	5V (up to 2.5A) from USB-C	5V (up to 2.5A) from USB-C	Up to 26V from external PSU 5V over USB-C with power limited to 2x5W	Up to 26V from external PSU 5V over USB-C with power limited to 2x5W	Up to 26V from external PSU 5V over USB-C with power limited to 2x5W	Up to 26V from external PSU 5V over USB-C with power limited to 2x5W
Connectivity	WiFi + BT4.2 + BLE W5500 Ethernet (optional module)	WiFi + BLE W5500 Ethernet (optional module)	WiFi + BT4.2 + BLE W5500 Ethernet (optional module)	WiFi + BLE W5500 Ethernet (optional module)	WiFi + BT4.2 + BLE W5500 Ethernet (optional module)	WiFi + BLE W5500 Ethernet (optional module)	WiFi + BT4.2 + BLE W5500 Ethernet (optional module)	WiFi + BLE W5500 Ethernet (optional module)

Onboard PSRAM

Audio streaming requires proper buffering to work, even with ESP32 500K of RAM it is a challenging task. For that reason, most of the projects will require WROVER modules that have onboard PSRAM chips. All ESP32 Audio boards have an 8MB PSRAM chip onboard, connected via a high-speed interface. Any code using PSRAM with just work out-of-the box.

Board Pinout

Amped-ESP32

Ethernet

Optional peripheral

Software samples

In the software section, two firmware examples are provided.

• esp32-i2s-bare is a base I2S implementation based on the ESP-IDF implementation.
• esp32-i2s-esp8266audio is based on the excellent ESP8266Audio library (it works with the whole ESP range, don't get fooled by the name), providing a minimum code implementation.
• esp32-i2s-web-radio is based on the same library, providing a minimal web radio stream player. It expects a playlist as input in the 'data' folder.

Platformio IDE

All samples are provided as Platformio IDE projects. After installing it, open the sample project. Select the proper environment based on your dock. Run the Build and Upload commands to install necessary tools and libraries, and build and upload the project to the board. Communication and proper upload method selection will be handled by IDE automatically.

Arduino IDE

Follow the ESP8266Audio library guide. Default settings will work out of the box with ESP8266 and ESP32 boards. For ESP32C3 and ESP32S2 board please adjust the pinout according to the above section

Home Assistant and ESPHome

Being an ESP32-based device, you can easily integrate it into your Home Assistant using ESPHome. Please find detailed instructions in the linked repo

Squeezelite-ESP32

Squeezelite-ESP32 is a multimedia software suite that started as a renderer (or player) of LMS (Logitech Media Server). Now it is extended with

• Spotify over-the-air player using SpotifyConnect (thanks to cspot)
• AirPlay controller (iPhone, iTunes ...) and enjoy synchronization multiroom as well (although it's AirPlay 1 only)
• Traditional Bluetooth device (iPhone, Android)

And LMS itself

• Streams your local music and connects to all major online music providers (Spotify, Deezer, Tidal, Qobuz) using Logitech Media Server - a.k.a LMS with multi-room audio synchronization.
• LMS can be extended by numerous plugins and can be controlled using a Web browser or dedicated applications (iPhone, Android).
• It can also send audio to UPnP, Sonos, Chromecast, and AirPlay speakers/devices.

All ESP32-based boards are tested with Squeezelite-ESP32 software, which can be flashed using nothing but a web browser. You can use Squeezelite-ESP32 installer for that purpose. more details and setup instructions can be found here

Squeezelite-ESP32 reboots and connection drops

The default configuration of the squeezelite-esp32 runs automatic discovery of the available LMS server nearby. In fact, it depends on it so much that in case the LMS service is not found on the network, it will reboot automatically (every few minutes).

In many cases, if you use squeezelite for AirPlay and Spotify only and don't have an LMS server, you need to disable discovery altogether. Currently, disabling Squeezelite in the GUI does not work correctly; it places too many spaces between the commands in the autoexec command. Following autoexec1 NVS setting can be used to disable it:

squeezelite -o i2s -s -disable -b 500:2000 -C 30 -d all=sdebug

Flashing ESP32-S3

ESP32-S3 boards have two ways of firmware update: (1) similarly to classing ESP32, they can be flashed over built-in UART, or (2) uniquely for S3, over built-in USB host controller. Since it is firmware-controlled, and may be disabled if not used (or, more commonly, not available with factory default empty firmware). When come unflashed, ESP32-S3 device comes into a boot loop, with a USB-CDC device appearing and disappearing every second, and **requires a special flashing initialisation sequence to get flashed**:

- Press IO0 (FLASH) button and keep it pressed

- Press RESET button and release FLASH button after

- ESP32-S3 will enter download mode, and USB-CDC device will appear and stay available

- Run flashing routine as usual, either through web-serial or `esp_tool`

- This time, it is not possible to reboot the device over USB, so press RESET once more

- Device will boot normally into firmware, and if USB-CDC is enabled in the firmware, you will be able to flash it normally, download mode and reset sequence will work over USB.

- If you manage to flash firmware without USB-CDC support, you need to go through the above sequence once more

Hardware

Please visit the hardware section for board schematics and PCB designs. Note that PCBs are shared as multi-layer PDFs.

Amped-ESP32 drawings

ESP32

Amped-ESP32 with TPA3128 amp

Originally, I used the TPA3110 amp with Amped Esparagus and Amped-ESP32 boards for its simplicity and availability. The only issue with TAP3110 is that it lacks the MUTE pin. It does have an STBY pin, but as it turned out, it is not pop-free, meaning each time you switch it on and off, the amp makes a loud pop in the speakers. I tried changing the level slowly, but it didn't help.

Help came with a newer TPA3128 amp with revision H of the Amped-ESP32

• It does have a true MUTE pin, and now it is software-controlled on Amped-ESP32. It means that the board starts dead-quiet, and it stays quiet when the audio is paused
• MUTE pin also disables PCM5100 DAC on rev H, so line-out is also dead quiet (not that it was noise before, but why not?)
• It can work with 4.5V, so it plays even when powered from a simple USB-C, similar to Louder-ESP32. TPA3110 needs at least 8V to spin up
• TPA3128 has a marginally better audio quality, as they say. I cannot hear the difference 😉

Optional SPI Ethernet module

Every board has a header that allows soldering in the W5500 SPI Ethernet module, which is very easy to find. The only downside is that with the module installed, the board will not fit the case unless it is cut to accommodate extra height.

Case

Amped-ESP32(S3) is mechanically compatible with Raspberry Pi 4 cases, tested with transparent ones. Also, community members created a few 3-D printable designs that can be found here and here