RedPill(+) ESP32-S3

by Munich Labs

A development board featuring ESP32-S3, designed for educational and prototyping purposes.

2× USB-C Native USB

Pinout

ESP32-S3

MCU

240MHz

clock

8MB

flash

512KB

SRAM

22· 20 ADC

GPIO

BLE 5.0+ WiFi

radio

Pinout

22 pins

View:

Pin	GPIO	Labels	Status	Capabilities
1	1	A0T1PWM	safe	adc · touch
2	2	A1T2PWM	safe	adc · touch
3	3	LED_BUILTINA2T3PWM	strapping	adc · touch
4	4	A3T4PWM	safe	adc · touch
5	5	A4T5PWM	safe	adc · touch
6	6	A5T6PWM	safe	adc · touch
7	7	A6T7PWM	safe	adc · touch
8	8	SDAA7T8PWM	safe	adc · touch · i2c
9	9	SCLA8T9PWM	strapping	adc · touch · i2c
10	10	A9T10PWM	strapping	adc · touch
11	11	A10T11PWM	strapping	adc · touch
12	12	A11T12PWM	strapping	adc · touch
13	13	A12T13PWM	strapping	adc · touch
14	14	A13T14PWM	strapping	adc · touch
15	15	SSA14PWM	safe	adc · spi
16	16	MOSIA15PWM	safe	adc · spi
17	17	MISOA16PWM	safe	adc · spi
18	18	SCKA17PWM	safe	adc · spi
19	19	A18PWM	uart	adc
20	20	A19PWM	uart	adc
21	43	TXPWM	strapping	uart
22	44	RXPWM	strapping	uart

Start with these

11 pins with no boot or system involvement

A0T1A1T2A3T4A4T5A5T6A6T7SDAA7SSA14MOSIA15MISOA16SCKA17

Freely assignable - no strapping, flash, USB or JTAG duties. Ideal first picks for buttons, sensors and LEDs.

Fine - with a little care

sampled at boot or shared with debug/serial

Pin	Label	What to know	Role
LED_BUILTIN	GPIO3	Sampled at reset to select JTAG interface (USB Serial/JTAG controller vs. external pins). Improper use can disable external JTAG or alter debug interface.	Strapping
TX	U0TXD (GPIO43)	Used for bootloader output and UART console logs. If repurposed, you will lose the default serial output (and programming via UART0).	Other
RX	U0RXD (GPIO44)	Used for bootloader input (download mode via serial). If repurposed, you cannot use the default UART0 download mode for programming the chip.	Other

Only if you know the tricks

wired to flash or USB - expect a fight

Pin	Label	What to know	Role
SCL	FSPIHD	Connected to external flash (data/hold signal) on most modules. Not recommended for use as GPIO, since it must remain dedicated to flash communication.	Flash
A9	FSPICS0	Used to select the external flash chip. It is required for flash access and cannot be repurposed without losing flash connectivity	Flash
A10	FSPID	Used as a data line for flash (and in-package PSRAM). It should not be used as GPIO when the flash/PSRAM is in use.	Flash
A11	FSPICLK	Drives the flash (and PSRAM) clock. This critical signal must be reserved for memory and not used as general GPIO.	Flash
A12	FSPIQ	Used as a data line for flash/PSRAM transfers. Not available for other uses when flash/PSRAM is connected.	Flash
A13	FSPIWP	Connected to external flash (data/write-protect signal). Not recommended as GPIO because it’s reserved for flash operations.	Flash
A18	USB_D-	By default connected to the on-chip USB Serial/JTAG controller. Using it as general GPIO without reconfiguring IO MUX will interfere with USB functionality.	USB
A19	USB_D+	By default connected to the on-chip USB Serial/JTAG controller. Using it as general GPIO without reconfiguring IO MUX will interfere with USB functionality.	USB

These are recommendations, not hard rules - with the right pull-ups, timing and boot-state awareness most pins can be made to work. When in doubt, start green.

Pinout notes The RedPill(+) ESP32-S3 pinout brings out 22 GPIO pins - every one of them usable in your project. For peripherals, I²C is mapped to SDA on GPIO8 and SCL on…

The RedPill(+) ESP32-S3 pinout brings out 22 GPIO pins - every one of them usable in your project.

For peripherals, I²C is mapped to SDA on GPIO8 and SCL on GPIO9; the SPI bus (MOSI, MISO, SCK, SS) is broken out in full; TX/RX on GPIO43 and GPIO44 cover serial logging and flashing.

On the analog side there are 20 ADC-capable pins for sensors and battery monitoring and 14 capacitive-touch inputs.

If you want zero surprises, A0, A1, A3, A4 and 7 more are free of any such role - the safest first picks. 3 of the exposed pins carry boot-time or system duties on the ESP32-S3 (LED_BUILTIN, TX and RX).

Getting started

flash your first firmware in ~2 minutes

Tool:

Connect over USB

Native USB - shows up as a port right away, no driver needed. Not detected? Hold BOOT while plugging in.

Match & flash

Set the Tools options shown, then click Upload.

Verify it runs

The onboard LED on GPIO1 blinks - swap the pin if your board's LED differs.

Set these in Tools · leave everything else at default

Arduino IDE 2.x — Tools Copy

Board: "ESP32S3 Dev Module"▸

USB CDC On Boot: "Enabled"▸

Flash Size: "8MB (64Mb)"▸

Flash Mode: "DIO"▸

PSRAM: "QSPI PSRAM"▸

Partition Scheme: "8M with spiffs (3MB APP / 1.5MB SPIFFS)" (default)▸

Upload Speed: "921600"▸

▸ every other Tools option — leave at default

Board: ESP32S3 Dev Module
USB CDC On Boot: Enabled
Flash Size: 8MB (64Mb)
Flash Mode: DIO
PSRAM: QSPI PSRAM
Partition Scheme: 8M with spiffs (3MB APP / 1.5MB SPIFFS)
Upload Speed: 921600

Find it: Tools ▸ Board ▸ ESP32 Arduino ▸ ESP32S3 Dev Module

blink.ino Copy

// blink the onboard LED
void setup() {
  pinMode(1, OUTPUT);
}
void loop() {
  digitalWrite(1, HIGH); delay(500);
  digitalWrite(1, LOW);  delay(500);
}

board to selectesp32-s3-devkitc-1⧉ copy

platformio.ini Copy

[env:redpill_esp32s3]
platform = espressif32
board = esp32-s3-devkitc-1
framework = arduino
monitor_speed = 115200
upload_speed = 921600
board_build.arduino.memory_type = qio_qspi
build_flags = -DBOARD_HAS_PSRAM

Find it: PlatformIO Home ▸ Boards, search esp32-s3-devkitc-1 — or type it after board =.

board to selectesp32-s3-devkitc-1⧉ copy

device.yaml Copy

esp32:
  board: esp32-s3-devkitc-1
  variant: redpill_esp32s3
  framework:
    type: esp-idf
psram:
  mode: quad
  speed: 80MHz

# blink - GPIO1
output:
  - platform: gpio
    pin: 1
    id: led_out
light:
  - platform: binary
    name: "LED"
    output: led_out

Find it: search ESPHome's board list for esp32-s3-devkitc-1 (same ids as PlatformIO).

esptool doesn't pick board settings — a prebuilt .bin already has them baked in. This is just the raw flash command.

terminal Copy

esptool.py --chip esp32s3 --port /dev/ttyACM0 \
  --baud 921600 write_flash 0x0 firmware.bin

--port = your /dev/tty* (macOS/Linux) or COMx (Windows).

Build details: sketch space 1310720 B · data 327680 B · DIO

Specifications

ESP32-S3

Compute

MCU

ESP32-S3

Clock

240 MHz

SRAM · Flash

512 KB · 8MB · 2MB (QSPI) PSRAM

Radio

Wi-Fi

802.11 b/g/n

Bluetooth

5.0 LE

Antenna

PCB

I/O

GPIO · ADC

22 · 20

UART · I²C · SPI

3 · 2 · 4

PWM

8 channels

Power

USB

USB-C (UART) · USB-C (native)

Serial

CP2102N

Boot address

0x0

Flashing

Upload · OTA

esptool_py · esp_ota

Flash · Boot mode

DIO · QIO

Sketch · Data

1.25 MB · 320 KB

The RedPill(+) ESP32-S3 uses esptool_py for firmware uploads, esp_ota for over-the-air (OTA) updates. Flash mode is DIO with QIO boot mode. The maximum sketch size is 1.25 MB with 320 KB available for data.

About this board

At its core is the ESP32-S3 - a dual-core Xtensa with vector extensions suited to AI workloads.

Onboard you'll find 2MB (QSPI) PSRAM and an addressable RGB LED (GPIO3).

Resources

ESP32-S3 datasheet espressif.com↗ Munich Labs - RedPill ESP32-S3 pinout munich-labs.com↗PlatformIO - Munich Labs RedPill ESP32-S3 docs.platformio.org↗arduino-esp32 variant (redpill_esp32s3 pins_arduino.h) github.com↗

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