LOLIN S3
A development board by Wemos based on the ESP32-S3-WROOM-1, featuring dual USB-C ports and compatibility with MicroPython and Arduino.
LOLIN S3 Pinout
23 pins · 2.54 mm pitch
| Pin | GPIO | Labels | Status | Capabilities | Notes |
|---|---|---|---|---|---|
| 1 | 1 | A0T1PWM | safe | adc · touch | |
| 2 | 2 | A1T2PWM | safe | adc · touch | |
| 3 | 3 | A2T3PWM | 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 | A7T8PWM | safe | adc · touch | |
| 9 | 9 | A8T9PWM | strapping | adc · touch | |
| 10 | 10 | SSA9T10PWM | strapping | adc · touch · spi | |
| 11 | 11 | MOSIA10T11PWM | strapping | adc · touch · spi | |
| 12 | 12 | SCKA11T12PWM | strapping | adc · touch · spi | |
| 13 | 13 | MISOA12T13PWM | strapping | adc · touch · spi | |
| 14 | 14 | A13T14PWM | strapping | adc · touch | |
| 15 | 15 | A14PWM | safe | adc | |
| 16 | 16 | A15PWM | safe | adc | |
| 17 | 17 | A16PWM | safe | adc | |
| 18 | 18 | A17PWM | safe | adc | |
| 19 | 38 | LED_BUILTINPWM | safe | - | |
| 20 | 41 | SCLPWM | strapping | i2c | |
| 21 | 42 | SDAPWM | strapping | i2c | |
| 22 | 43 | TXPWM | uart | uart | |
| 23 | 44 | RXPWM | uart | uart |
Start with these
12 pins with no boot or system involvementFreely assignable - no strapping, flash, USB or JTAG duties. Ideal first picks for buttons, sensors and LEDs.
Fine - with a little care
11 pins · 6 things to knowA2GPIO3 Bootstrapping pin (controls JTAG signal source) Strapping
Sampled at reset to select JTAG interface (USB Serial/JTAG controller vs. external pins). Improper use can disable external JTAG or alter debug interface.
A8GPIO9SSGPIO10MOSIGPIO11SCKGPIO12MISOGPIO13A13GPIO14 General-purpose SPI2 (FSPI) IO MUX pins Other
IO MUX pin of the general-purpose SPI2 (FSPI) bus, not of the in-package flash - that sits on GPIO26-32. The datasheet lists it as a priority-2 pin ("can be freely used without restrictions"), so it is only taken if your board wires flash, an SD card or a display to FSPI.
- A8General-purpose SPI2 (FSPI) IO MUX pin - hold/data line (FSPIHD)
- SSGeneral-purpose SPI2 (FSPI) IO MUX pin - chip select (FSPICS0)
- MOSIGeneral-purpose SPI2 (FSPI) IO MUX pin - data in (FSPID)
- SCKGeneral-purpose SPI2 (FSPI) IO MUX pin - clock (FSPICLK)
- MISOGeneral-purpose SPI2 (FSPI) IO MUX pin - data out (FSPIQ)
- A13General-purpose SPI2 (FSPI) IO MUX pin - write-protect/data line (FSPIWP)
SCLGPIO41 JTAG test data in pin (MTDI) JTAG
Default JTAG TDI input for debugging. Should be reserved for JTAG or left unused if JTAG is to remain available.
SDAGPIO42 JTAG test mode select pin (MTMS) JTAG
Default JTAG TMS signal for debugging. Using this pin for other purposes will disable the JTAG interface (unless JTAG is rerouted to USB).
TXGPIO43 UART0 transmit pin (U0TXD), default serial console TX UART
Used for bootloader output and UART console logs. If repurposed, you will lose the default serial output (and programming via UART0).
RXGPIO44 UART0 receive pin (U0RXD), default serial console RX UART
Used for bootloader input (download mode via serial). If repurposed, you cannot use the default UART0 download mode for programming the chip.
All 23 pins on the LOLIN S3 are usable GPIO, spaced at the standard 2.54 mm pitch.
Peripheral wiring is straightforward: I²C is mapped to SDA on GPIO42 and SCL on GPIO41; the SPI bus (MOSI, MISO, SCK, SS) is broken out in full; TX/RX on GPIO43 and GPIO44 cover serial logging and flashing.
Beyond plain digital I/O you get 18 ADC-capable pins for sensors and battery monitoring and 14 capacitive-touch inputs.
11 of the exposed pins carry boot-time or system duties on the ESP32-S3 (A2, A8, SS and 8 more) - check the guidance above before wiring anything to them. A0, A1, A3, A4 and 8 more are free of any such role - the safest first picks.
Getting started
flash your first firmware in ~2 minutesBoard: ESP32S3 Dev Module USB CDC On Boot: Enabled Flash Size: 16MB (128Mb) Flash Mode: DIO PSRAM: OPI PSRAM Partition Scheme: 16M Flash (3MB APP/9.9MB FATFS) Upload Speed: 921600
// toggle GPIO1 - wire an LED and resistor to it
void setup() {
pinMode(1, OUTPUT);
}
void loop() {
digitalWrite(1, HIGH); delay(500);
digitalWrite(1, LOW); delay(500);
}[env:lolin_s3]
platform = espressif32
board = esp32-s3-devkitc-1
framework = arduino
monitor_speed = 115200
upload_speed = 921600
board_build.arduino.memory_type = qio_opi
build_flags = -DBOARD_HAS_PSRAMesp32-s3-devkitc-1 - or type it after board =.esp32:
board: esp32-s3-devkitc-1
variant: esp32s3
framework:
type: esp-idf
psram:
mode: octal
speed: 80MHz
# blink - GPIO1
output:
- platform: gpio
pin: 1
id: led_out
light:
- platform: binary
name: "LED"
output: led_outesp32-s3-devkitc-1 (same ids as PlatformIO).esptool.py --chip esp32s3 --port /dev/ttyACM0 \
--baud 921600 write_flash 0x0 firmware.bin--port = your /dev/tty* (macOS/Linux) or COMx (Windows).Specifications
ESP32-S3 · 65.3 × 25.4 mm · vs other ESP32 chips →Dimensions
About this board
Inside sits the ESP32-S3 - a dual-core Xtensa with vector extensions suited to AI workloads.
At $6.90 it's cheaper than most ESP32-S3 boards, which usually run around $29.
Around the module: 8MB (OPI) PSRAM, an addressable RGB LED (GPIO38) and Reset/Boot buttons.
Where to buy
prices are typical street pricesResources
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