The ESP32-S3-DevKitC-1 has a lot of GPIOs, but not every pin is equally convenient to use.

Some pins affect boot, some are shared with native USB or debugging, and GPIO35–37 may be unavailable depending on the flash and PSRAM configuration of the module fitted to your board.

This guide focuses on ESP32-S3-DevKitC-1 pinout and GPIO selection, so you can connect sensors, relays, displays, SPI devices, UART peripherals and USB hardware without unexpected boot or peripheral conflicts.

The ESP32-S3-DevKitC-1 is Espressif’s official entry-level development board for ESP32-S3-WROOM-1, ESP32-S3-WROOM-1U and ESP32-S3-WROOM-2 modules.

The ESP32-S3 combines a dual-core Xtensa LX7 processor with 2.4 GHz Wi-Fi, Bluetooth Low Energy, native USB and a flexible GPIO matrix.

Scope: This guide covers the official ESP32-S3-DevKitC-1 with the J1 and J3 22-pin headers. The board exists in several flash/PSRAM configurations and in more than one hardware revision, which matters for a few GPIOs.

You can compare your board with the official ESP32-S3-DevKitC-1 documentation.

ESP32-S3 DevKitC-1 GPIO Quick Reference

If you simply want to know which pins to use, start here.

GPIO group	Recommendation
GPIO1, 2, 4–18, 21, 47	Best general-purpose starting points
GPIO0, 3, 45, 46	Avoid for normal peripherals: strapping pins
GPIO19, 20	Reserve when using native USB
GPIO35, 36, 37	Module-dependent: unavailable on several Octal-memory versions
GPIO38	RGB LED on DevKitC-1 v1.1
GPIO48	RGB LED on the original DevKitC-1
GPIO39–42	Usable, but also associated with external JTAG
GPIO43, 44	UART0 / USB-to-UART console
GPIO26–32	Internal flash/PSRAM bus; not broken out for normal use

For a project that needs ordinary digital inputs and outputs, GPIO1, GPIO2, GPIO4–18, GPIO21 and GPIO47 are the lowest-drama group to start with.

J1

No.	Name	Type 1	Function
1	3V3	P	3.3 V power supply
2	3V3	P	3.3 V power supply
3	RST	I	EN
4	4	I/O/T	RTC_GPIO4, GPIO4, TOUCH4, ADC1_CH3
5	5	I/O/T	RTC_GPIO5, GPIO5, TOUCH5, ADC1_CH4
6	6	I/O/T	RTC_GPIO6, GPIO6, TOUCH6, ADC1_CH5
7	7	I/O/T	RTC_GPIO7, GPIO7, TOUCH7, ADC1_CH6
8	15	I/O/T	RTC_GPIO15, GPIO15, U0RTS, ADC2_CH4, XTAL_32K_P
9	16	I/O/T	RTC_GPIO16, GPIO16, U0CTS, ADC2_CH5, XTAL_32K_N
10	17	I/O/T	RTC_GPIO17, GPIO17, U1TXD, ADC2_CH6
11	18	I/O/T	RTC_GPIO18, GPIO18, U1RXD, ADC2_CH7, CLK_OUT3
12	8	I/O/T	RTC_GPIO8, GPIO8, TOUCH8, ADC1_CH7, SUBSPICS1
13	3	I/O/T	RTC_GPIO3, GPIO3, TOUCH3, ADC1_CH2
14	46	I/O/T	GPIO46
15	9	I/O/T	RTC_GPIO9, GPIO9, TOUCH9, ADC1_CH8, FSPIHD, SUBSPIHD
16	10	I/O/T	RTC_GPIO10, GPIO10, TOUCH10, ADC1_CH9, FSPICS0, FSPIIO4, SUBSPICS0
17	11	I/O/T	RTC_GPIO11, GPIO11, TOUCH11, ADC2_CH0, FSPID, FSPIIO5, SUBSPID
18	12	I/O/T	RTC_GPIO12, GPIO12, TOUCH12, ADC2_CH1, FSPICLK, FSPIIO6, SUBSPICLK
19	13	I/O/T	RTC_GPIO13, GPIO13, TOUCH13, ADC2_CH2, FSPIQ, FSPIIO7, SUBSPIQ
20	14	I/O/T	RTC_GPIO14, GPIO14, TOUCH14, ADC2_CH3, FSPIWP, FSPIDQS, SUBSPIWP
21	5V	P	5 V power supply
22	G	G	Ground

J3

No.	Name	Type	Function
1	G	G	Ground
2	TX	I/O/T	U0TXD, GPIO43, CLK_OUT1
3	RX	I/O/T	U0RXD, GPIO44, CLK_OUT2
4	1	I/O/T	RTC_GPIO1, GPIO1, TOUCH1, ADC1_CH0
5	2	I/O/T	RTC_GPIO2, GPIO2, TOUCH2, ADC1_CH1
6	42	I/O/T	MTMS, GPIO42
7	41	I/O/T	MTDI, GPIO41, CLK_OUT1
8	40	I/O/T	MTDO, GPIO40, CLK_OUT2
9	39	I/O/T	MTCK, GPIO39, CLK_OUT3, SUBSPICS1
10	38	I/O/T	GPIO38, FSPIWP, SUBSPIWP, RGB LED
11	37	I/O/T	SPIDQS, GPIO37, FSPIQ, SUBSPIQ
12	36	I/O/T	SPIIO7, GPIO36, FSPICLK, SUBSPICLK
13	35	I/O/T	SPIIO6, GPIO35, FSPID, SUBSPID
14	0	I/O/T	RTC_GPIO0, GPIO0
15	45	I/O/T	GPIO45
16	48	I/O/T	GPIO48, SPICLK_N, SUBSPICLK_N_DIFF
17	47	I/O/T	GPIO47, SPICLK_P, SUBSPICLK_P_DIFF
18	21	I/O/T	RTC_GPIO21, GPIO21
19	20	I/O/T	RTC_GPIO20, GPIO20, U1CTS, ADC2_CH9, CLK_OUT1, USB_D+
20	19	I/O/T	RTC_GPIO19, GPIO19, U1RTS, ADC2_CH8, CLK_OUT2, USB_D-
21	G	G	Ground
22	G	G	Ground

P: Power supply; I: Input; O: Output; T: High impedance.

Board Overview

The ESP32-S3-DevKitC-1 exposes most usable ESP32-S3 signals through two 22-pin headers labelled J1 and J3.

The board includes:

• ESP32-S3-WROOM-1, WROOM-1U or WROOM-2 module
• 5 V to 3.3 V regulator
• USB-to-UART programming port
• native ESP32-S3 USB port
• BOOT button
• RESET / EN button
• addressable RGB LED
• 3.3 V power LED
• two 22-pin headers

The USB-to-UART port provides the traditional serial programming interface.

The second USB connector is connected directly to the ESP32-S3’s native USB peripheral and can be used for USB devices, USB host applications, firmware upload and built-in USB JTAG.

Watch the RGB LED pin

There are two DevKitC-1 hardware revisions still in circulation.

Original ESP32-S3-DevKitC-1:

• RGB LED → GPIO48

ESP32-S3-DevKitC-1 v1.1:

• RGB LED → GPIO38

So don’t blindly assume GPIO48 controls the LED just because an older tutorial says so.

If you don’t know which revision you have, treat both GPIO38 and GPIO48 as potentially board-connected until you identify it.

Power Supply Options

There are three basic ways to power the DevKitC-1:

• through the USB ports
• through 5V + GND
• through 3V3 + GND

The USB-to-UART and native USB ports form the normal USB power option; Espressif allows either USB connector, or both, to be connected.

For normal development, the easiest option is simply to use the USB-to-UART connector.

If you’re powering the board from another system:

5V pin

Feed the board with a stable 5 V supply and let its onboard regulator generate 3.3 V.

This is a good option when powering an ESP32 project from something such as a 12 V supply through a DC/DC converter.

3V3 pin

You can bypass the onboard regulator and feed regulated 3.3 V directly.

Your external supply needs enough transient capability for Wi-Fi activity and any peripherals connected to the board.

ESP32-S3 GPIOs are 3.3 V logic

Do not connect 5 V signals directly to an ESP32-S3 GPIO.

Use a level shifter, resistor divider or suitable interface circuit when connecting 5 V hardware.

ESP32-S3 GPIO Basics

The ESP32-S3 has 45 physical GPIOs:

GPIO0–21 and GPIO26–48

GPIO22–25 do not exist.

The important word here is physical. Not every chip GPIO is actually available on the DevKitC-1 headers.

The DevKitC-1 breaks out the GPIOs that remain available after the module’s flash/PSRAM connections are taken into account.

ESP32-S3 GPIOs are highly multiplexed. Through the GPIO matrix, peripherals such as I²C, SPI, UART, PWM and I²S can be routed to many different pins instead of being permanently tied to one fixed pinout.

That flexibility is one of the S3’s biggest advantages, but it also means a pin marked with one peripheral function can often be used for something completely different.

Strapping Pins: GPIO0, GPIO3, GPIO45 and GPIO46

The ESP32-S3 has four strapping pins:

• GPIO0
• GPIO3
• GPIO45
• GPIO46

Their logic levels are sampled during reset and can affect how the chip starts.

Their functions include:

GPIO	Boot-time function
GPIO0	Boot mode
GPIO46	Boot mode and ROM output behaviour
GPIO45	VDD_SPI configuration
GPIO3	JTAG source selection

GPIO0 is the one most users encounter because pulling it LOW while resetting the ESP32-S3 enters download mode.

That’s exactly what the BOOT button does.

After boot, these pins can operate as GPIOs, but attaching external circuitry that holds one of them at the wrong level during reset can produce confusing startup problems.

Recommendation

Unless you’re short of pins, leave GPIO0, GPIO3, GPIO45 and GPIO46 out of ordinary sensor, relay and display wiring.

There are enough easier GPIOs on the S3 that using strapping pins usually isn’t worth the trouble.

Safe GPIOs for Everyday Projects

For a project that must work across the common DevKitC-1 variants, a useful default GPIO pool is:

GPIO1, GPIO2, GPIO4–18, GPIO21 and GPIO47

These avoid:

• the four strapping pins
• native USB
• the module-dependent GPIO35–37 group
• the onboard RGB LED on either board revision
• UART0
• the traditional external JTAG pins

That doesn’t mean all the other GPIOs are unusable.

It simply means these pins generally require the least thought.

GPIOs that are usable with conditions

GPIO19 and GPIO20

Perfectly usable as GPIO or ADC inputs if you are not using native USB.

If native USB is active, reserve them for USB.

GPIO35, GPIO36 and GPIO37

Whether these pins are available depends on the module fitted to your DevKitC-1.

On boards using ESP32-S3-WROOM modules with certain Octal flash/PSRAM configurations, GPIO35–37 are used internally and cannot be used externally.

If you are writing a guide or designing something intended to work with multiple DevKitC-1 versions, don’t depend on GPIO35–37.

GPIO38 and GPIO48

One of these drives the addressable RGB LED depending on the board revision.

They can still be useful when you know exactly which DevKitC-1 revision you have.

GPIO39–42

These pins can be GPIOs, but they are also the traditional JTAG signals:

• GPIO39 → MTCK
• GPIO40 → MTDO
• GPIO41 → MTDI
• GPIO42 → MTMS

If you don’t use external JTAG debugging, they become useful additional GPIOs.

GPIO43 and GPIO44

These are the default UART0 console signals:

• GPIO43 → TX0
• GPIO44 → RX0

They are connected to the board’s USB-to-UART interface.

You can repurpose them, but doing so can interfere with serial logging, programming workflows or anything connected through the USB-to-UART bridge.

ADC Pins

The ESP32-S3 has two 12-bit SAR ADC units providing 20 analog channels.

ADC1

ADC1 uses GPIO1–10:

GPIO	ADC channel
GPIO1	ADC1_CH0
GPIO2	ADC1_CH1
GPIO3	ADC1_CH2
GPIO4	ADC1_CH3
GPIO5	ADC1_CH4
GPIO6	ADC1_CH5
GPIO7	ADC1_CH6
GPIO8	ADC1_CH7
GPIO9	ADC1_CH8
GPIO10	ADC1_CH9

GPIO3 is also a strapping pin, so I would normally use GPIO1, GPIO2 or GPIO4–10 first.

ADC2

ADC2 uses GPIO11–20:

GPIO	ADC channel
GPIO11	ADC2_CH0
GPIO12	ADC2_CH1
GPIO13	ADC2_CH2
GPIO14	ADC2_CH3
GPIO15	ADC2_CH4
GPIO16	ADC2_CH5
GPIO17	ADC2_CH6
GPIO18	ADC2_CH7
GPIO19	ADC2_CH8
GPIO20	ADC2_CH9

ADC2 is shared with the Wi-Fi subsystem.

Current ESP-IDF handles ADC2 oneshot access better than older ESP32 software did, but ADC2 remains more constrained when Wi-Fi is active, and ADC2 continuous-mode sampling is not recommended on the ESP32-S3.

Best practical choice for analog sensors

For a normal Wi-Fi project, use ADC1 on GPIO1–10 where possible.

My first choices would be:

GPIO1, GPIO2, GPIO4, GPIO5, GPIO6 or GPIO7

GPIO8–10 are also excellent, although you may want to reserve GPIO8/9 for I²C and GPIO10 for SPI chip select if you follow the mappings later in this guide.

Never allow the analog input to exceed the ESP32-S3’s 3.3 V supply domain.

For accurate voltage measurements, also remember that an ESP32 ADC is not a laboratory ADC: use calibration if accuracy matters.

Capacitive Touch Pins

The ESP32-S3 has 14 capacitive touch channels on GPIO1–14.

GPIO	Touch channel
GPIO1	TOUCH1
GPIO2	TOUCH2
GPIO3	TOUCH3
GPIO4	TOUCH4
GPIO5	TOUCH5
GPIO6	TOUCH6
GPIO7	TOUCH7
GPIO8	TOUCH8
GPIO9	TOUCH9
GPIO10	TOUCH10
GPIO11	TOUCH11
GPIO12	TOUCH12
GPIO13	TOUCH13
GPIO14	TOUCH14

For a straightforward touch input, I would avoid the GPIO3 strapping pin and start with:

GPIO4–14

Touch inputs can also be used as wake-up sources in low-power projects.

Native USB Pins

Unlike the original ESP32, the ESP32-S3 includes native full-speed USB OTG.

The USB data pins are fixed:

• GPIO19 → USB D-
• GPIO20 → USB D+

These lines are connected to the ESP32-S3 USB connector on the DevKitC-1.

If you’re using native USB for something such as:

• USB CDC serial
• HID keyboard or mouse
• MIDI
• USB storage
• USB host
• USB Serial/JTAG

treat GPIO19 and GPIO20 as reserved USB pins.

Do not attach ordinary sensors or outputs to them while using native USB.

If native USB isn’t being used, GPIO19 and GPIO20 can be repurposed as normal GPIO or ADC2 inputs.

I²C Pins

The ESP32-S3 does not force you to use one fixed pair of pins for I²C.

The GPIO matrix lets you route SDA and SCL to many GPIOs.

For the DevKitC-1, a clean default is:

Function	GPIO
SDA	GPIO8
SCL	GPIO9

These pins avoid boot, USB, UART and flash/PSRAM complications.

Arduino example:

#include <Wire.h>

void setup() {
  Wire.begin(8, 9);   // SDA, SCL
}

void loop() {
}

That gives you a predictable I²C connection for devices such as a BME280, OLED display, RTC, INA219 or other sensor.

You can choose other GPIOs if GPIO8/9 are already needed elsewhere.

SPI Pins

SPI is another area where the S3’s GPIO matrix provides a lot of freedom.

A particularly sensible general-purpose SPI2 mapping on the DevKitC-1 is:

SPI signal	GPIO
CS	GPIO10
MOSI	GPIO11
SCK	GPIO12
MISO	GPIO13

This group is much better as a general recommendation than GPIO35–38 because it works across the common DevKitC-1 memory variants.

It is suitable for:

• TFT displays
• SD card modules
• Ethernet controllers
• ADC/DAC chips
• RF modules
• SPI sensors

Additional control signals such as display DC, RESET and backlight can then use GPIO14–16 or another free GPIO.

For example:

Display function	GPIO
CS	GPIO10
MOSI	GPIO11
SCK	GPIO12
MISO	GPIO13
DC	GPIO14
RESET	GPIO15
Backlight	GPIO16

Because the signals can be routed through the GPIO matrix, these aren’t mandatory pins—they are simply a very convenient layout.

UART and Serial Pins

The ESP32-S3 has multiple UART controllers, and their signals can also be remapped.

On the DevKitC-1, UART0 is used for the normal serial console:

• GPIO43 → UART0 TX
• GPIO44 → UART0 RX

For that reason, I recommend leaving GPIO43 and GPIO44 alone unless you deliberately want to repurpose the console.

For a second serial peripheral, GPIO17 and GPIO18 form a very convenient pair:

Function	GPIO
UART1 TX	GPIO17
UART1 RX	GPIO18

This is useful for:

• GPS modules
• RS-485 transceivers
• energy meters
• other microcontrollers
• serial displays
• GSM/LTE modules

Arduino example:

HardwareSerial DeviceSerial(1);

void setup() {
  DeviceSerial.begin(9600, SERIAL_8N1, 18, 17);
}

Remember that Arduino’s begin() arguments are RX first, then TX.

PWM Pins

The ESP32-S3 LED PWM controller can be routed through the GPIO matrix, so most ordinary output-capable GPIOs can be used for PWM.

For LEDs, fan control, dimming and similar applications, pick from the normal safe GPIO pool rather than wasting a special-function pin.

Good examples include:

GPIO4, GPIO5, GPIO6, GPIO7, GPIO14, GPIO15, GPIO16, GPIO17, GPIO18, GPIO21 or GPIO47

For motors, relays and other inductive loads, the GPIO should drive a proper transistor, MOSFET or driver circuit rather than powering the load directly.

Practical ESP32-S3-DevKitC-1 Pin Recipes

Wi-Fi sensor with I²C and a relay

A simple arrangement that leaves all problematic pins alone:

Function	Recommended GPIO	Notes
I²C SDA	GPIO8	Sensors / OLED
I²C SCL	GPIO9	Sensors / OLED
Relay	GPIO21	Simple digital output
Button / reed switch	GPIO4	Digital input
Analog sensor	GPIO1 or GPIO2	ADC1

This leaves native USB, UART0, strapping pins and flash/PSRAM-related pins untouched.

SPI TFT display

A convenient mapping is:

Function	GPIO
CS	GPIO10
MOSI	GPIO11
SCK	GPIO12
MISO	GPIO13
DC	GPIO14
RESET	GPIO15
Backlight	GPIO16

That gives you a neat sequential group on the J1 side of the board.

Native USB device with button and status indication

Function	GPIO
USB D-	GPIO19
USB D+	GPIO20
User button	GPIO4
Extra status LED	GPIO5

For the onboard RGB LED, check your board revision first:

• original DevKitC-1 → GPIO48
• DevKitC-1 v1.1 → GPIO38

UART device plus I²C sensors

Function	GPIO
UART RX	GPIO18
UART TX	GPIO17
I²C SDA	GPIO8
I²C SCL	GPIO9
Digital output	GPIO21

This combination keeps UART0 free for debugging and programming.

Pins I Would Avoid First

When starting a new DevKitC-1 project, I would not choose these pins unless there is a specific reason.

GPIO0, GPIO3, GPIO45 and GPIO46

Strapping pins. They can work after startup, but external circuitry can interfere with boot.

GPIO19 and GPIO20

Keep free when using native USB.

GPIO35, GPIO36 and GPIO37

Availability depends on the module’s flash/PSRAM configuration.

Don’t design around them unless you have checked the exact module fitted to your board.

GPIO38 and GPIO48

One is connected to the RGB LED depending on the DevKitC-1 revision.

GPIO43 and GPIO44

UART0 console and USB-to-UART interface.

GPIO39–42

Fine as GPIO when you’re not using traditional external JTAG, but I would use the completely free pins first.

ESP32-S3-DevKitC-1 Rules of Thumb

The ESP32-S3-DevKitC-1 is an extremely flexible development board once you separate the genuinely free GPIOs from pins that have additional jobs.

The practical rules are simple:

• Start with GPIO1, 2, 4–18, 21 and 47 for ordinary I/O
• Avoid GPIO0, 3, 45 and 46 for normal peripherals
• Reserve GPIO19 and 20 when using native USB
• Don’t assume GPIO35–37 are available without checking your exact module
• Check whether your RGB LED is on GPIO38 or GPIO48
• Keep GPIO43/44 free if you want the normal UART console
• Prefer ADC1 on GPIO1–10 for Wi-Fi projects
• GPIO8/9 make a convenient I²C pair
• GPIO10–13 make a convenient SPI bus
• GPIO17/18 make a convenient additional UART

Follow those rules and the ESP32-S3-DevKitC-1 becomes a very predictable platform for Wi-Fi sensors, Home Assistant nodes, relays, displays, native USB devices and general ESP32-S3 development.

The important thing isn’t memorising every alternate peripheral function printed on a pinout diagram. It is knowing which GPIOs have hidden responsibilities and choosing the uncomplicated pins first.