lucky-cat/docs/gpio-map.md

ESP32-S3 GPIO Map

This document defines the reference GPIO assignments for the ESP32-S3 board, current as of April 8, 2026. Signal direction is described from the MCU's perspective.

GPIO Table

U4 Pin	GPIO	Net	Direction	Connection / Function	Notes
1	GND	GND	N/A	Ground reference	Ground reference
2	3V3	3V3	Power	3.3 V supply rail	Power rail
3	EN/RST	EN	Input	Chip enable and reset input	Reset and enable
4	GPIO4	UNASSIGNED	N/A	No connection assigned	Reserved; no signal assigned
5	GPIO5	UNASSIGNED	N/A	No connection assigned	Reserved; no signal assigned
6	GPIO6	ESP_IO6	Output	Display interface CS	U9
7	GPIO7	ESP_IO7	Output	Display interface A0 (RS)	U9
8	GPIO15	ESP_IO15	Input	Function key K2	10 kOhm pull-up to 3V3; pulled to GND when pressed
9	GPIO16	UNASSIGNED	N/A	No connection assigned	Reserved; no signal assigned
10	GPIO17	ESP_IO17	Output	Display interface SDA	U9
11	GPIO18	ESP_IO18	Output	Display interface SCK	U9
12	GPIO8	UNASSIGNED	N/A	No connection assigned	Reserved; no signal assigned
13	GPIO19	ESP_D_N	Bidirectional	USB D-	Type-C
14	GPIO20	ESP_D_P	Bidirectional	USB D+	Type-C
15	GPIO3	ESP_IO3	Output	Display interface RST	U9 JLX240-00302
16	GPIO46	UNASSIGNED	N/A	No connection assigned	Reserved; no signal assigned
17	GPIO9	ESP_IO9	Output	Display interface LEDA	U9
18	GPIO10	SWING_PWM	Output	Swing coil control interface	J3
19	GPIO11	UNASSIGNED	N/A	No connection assigned	Reserved; no signal assigned
20	GPIO12	PA_CTRL	Output	NS4150B CTRL	Amplifier control
21	GPIO13	IN1	Output	ULN2003 IN1	Stepper motor phase control
22	GPIO14	IN2	Output	ULN2003 IN2	Stepper motor phase control
23	GPIO21	IN3	Output	ULN2003 IN3	Stepper motor phase control
24	GPIO47	IN4	Output	ULN2003 IN4	Stepper motor phase control
25	GPIO48	SW_1	Input	Microswitch interface for turntable calibration	External connector J7
26	GPIO45	SW_2	Input	Microswitch interface for slot-machine feature	External connector J?
27	GPIO0	UNLABELED	Input	K1 switch to GND	Purpose not annotated; commonly used for boot or download strapping
28	GPIO35	UNASSIGNED	N/A	No connection assigned	Reserved; no signal assigned
29	GPIO36	UNASSIGNED	N/A	No connection assigned	Reserved; no signal assigned
30	GPIO37	UNASSIGNED	N/A	No connection assigned	Reserved; no signal assigned
31	GPIO38	I2S_MCLK	Output	ES8311 MCLK	Audio interface
32	GPIO39	I2S_SCLK	Output	ES8311 SCLK	Audio interface
33	GPIO40	I2S_DSDIN	Output	ES8311 DSDIN	Audio interface
34	GPIO41	I2S_LRCK	Output	ES8311 LRCK	Audio interface
35	GPIO42	I2S_ASDOUT	Input	ES8311 ASDOUT	Audio interface
36	RXD0	esp_tx	Input	Debug UART	Routed to J2
37	TXD0	esp_rx	Output	Debug UART	Routed to J2
38	GPIO2	IO2_I2C_SCL	Bidirectional	ES8311 control interface SCL	Audio codec
39	GPIO1	IO1_I2C_SDA	Bidirectional	ES8311 control interface SDA	Audio codec
40	GND	GND	N/A	Ground reference	Ground reference
41	GND	GND	N/A	Ground reference	Ground reference