New custom PCB - MAX98357 powered stereo amp

A project log for Loud ESP

I'm looking for perfect audio DAC for ESP8266/ESP32

andriymalyshenkoandriy.malyshenko 02/09/2022 at 21:310 Comments

Based in the investigation done in this project I've decided to build series of development boards with audio capable DAC, starting from the ones with built-in amp. Since I already have in mind a kind of project I'd like to implement (no spoilers) i also planned some advanced peripheral on the board to support those projects.

To be fair I've done both ESP8266 and ESP32, since in my opinion they are both great chips and being similar on the paper, they are in a quite different league if it comes to power reserves, therefore they are not really competing. For smaller projects I prefer simplicity of ESP8266, for larger projects - spacier ESP32.

I'm using them both quite regularly, so why not to have 2 development boards instead of one.

With that said, here they are.

ESP8266 closer look

ESP32 closer look

So commonly they have

- Stereo DAC with built in amp (2x MAX98357)

- Power circuit with backup Li-Ion battery (using built-in battery holder or external using battery socket)

- Battery charging IC and battery overcurrent protection IC

- Battery voltage measurement with built-in ADC

- Boost converter to keep the music going when battery voltage is too low

- TFT screen (with touch support on the ESP32)

- USB-serial bridge for normal flashing and serial debugging, with auto-flashing circuit

- IR reciever to support IR remotes

- Micro SD-CARD socket

Given the extra pins on the ESP32 is exclusively has

- RGB led on the board and connector for the external RGB LED strip


- Joystick OR rotary encoder

- Few HW touch pads

- JTAG header for real debugging

Currently I'm testing all the peripherals and doing some small improvements. Also I've adopted cspot repo to play Spotify as a smart speaker, and looking into adding visual feedback to above project. I want to put it into the case, for that purpose I've bough broken smart speaker and planning to replace internals with my dev board. More details in the next post (hopefully).