ESP32-C3 Super Mini front - USB-C port and chip

Microcontroller

ESP32-C3

Using the ESP32-C3 with the MAX98357A guide - what changes, what stays the same

The ESP32-C3 is a single-core RISC-V microcontroller with WiFi and Bluetooth. It has one I2S peripheral and works with the MAX98357A guide - the only changes needed are the board selection in Arduino IDE and the three pin numbers in the sketch.

Pins to use

ESP32-C3 Pin	MAX98357A Pin	Signal
5V	VIN	Power
GND	GND	Common ground
GPIO4	BCLK	I2S bit clock
GPIO5	LRC	I2S word select (LRCLK)
GPIO6	DIN	I2S data out from ESP32-C3

Pins to avoid

GPIO range	Why to avoid
GPIO0	Boot strapping pin - affects startup mode
GPIO8, GPIO9	Strapping pins - can interfere with flashing
GPIO11-17	SPI flash - connected to internal flash chip
GPIO18, GPIO19	USB D- / D+ on boards with USB-CDC

Sketch changes

The guide sketches already include the ESP32-C3 pin defines as commented-out alternatives. Comment out the ESP32 Dev Board lines and uncomment the C3 lines:

// comment these out:
//#define I2S_BCLK   27
//#define I2S_LRCLK  14
//#define I2S_DOUT   13

// uncomment these:
#define I2S_BCLK   4
#define I2S_LRCLK  5
#define I2S_DOUT   6

The guide uses the legacy I2S driver which works on ESP32-C3 with Arduino-ESP32 v2.x, and still compiles on v3.x with deprecation warnings. Everything else in the sketch stays the same.

Arduino IDE settings

Setting	Value
Board	ESP32C3 Dev Module
Partition Scheme	Huge APP (3MB No OTA) - same as the guide
USB CDC On Boot	Enabled (needed if you use Serial.print for debugging)

What stays the same

Wiring to the MAX98357A module - pin functions are identical
Audio preparation with espeak-ng and ffmpeg
WAV-to-header Python script
The rest of the sketch - I2S config, DMA setup, playback loop

Key details

Use GPIO4 (BCLK), GPIO5 (LRC), GPIO6 (DIN)
Select "ESP32C3 Dev Module" in Arduino IDE
Only change needed in the sketch: the three pin #defines
Same wiring to MAX98357A, same audio prep, same partition scheme
Avoid GPIO8, GPIO9, and GPIO11-17