LOLIN S2 Mini
Compact ESP32-S2 board by Wemos with USB-C in a small castellated form factor - great for space-saving embedded builds.
LOLIN S2 Mini Pinout
32 pins · 2.54 mm pitch
| Pin | GPIO | Labels | Status | Capabilities | Notes |
|---|---|---|---|---|---|
| 1 | - | VBUS5V | power | - | USB VBUS - WEMOS prints VBUS on this pad; unregulated 5V in or out |
| 2 | - | GND | ground | - | Ground connection |
| 3 | - | 3V33.3V | power | - | 3.3V power output |
| 4 | 1 | IO1GPIO1 | safe | - | GPIO |
| 5 | 2 | IO2GPIO2 | safe | adc | GPIO, ADC |
| 6 | 3 | IO3GPIO3 | safe | - | GPIO |
| 7 | 4 | IO4GPIO4 | safe | adc | GPIO, ADC |
| 8 | 5 | IO5GPIO5 | safe | - | GPIO |
| 9 | 6 | IO6GPIO6 | safe | - | GPIO |
| 10 | 7 | IO7GPIO7 | safe | - | GPIO |
| 11 | 8 | IO8GPIO8 | safe | - | GPIO |
| 12 | 9 | IO9GPIO9 | strapping | - | GPIO |
| 13 | 10 | IO10GPIO10 | strapping | - | GPIO |
| 14 | 11 | IO11GPIO11 | strapping | - | GPIO |
| 15 | 12 | IO12GPIO12 | strapping | adc | GPIO, ADC |
| 16 | 13 | IO13GPIO13 | strapping | adc | GPIO, ADC |
| 17 | 14 | IO14GPIO14 | strapping | adc | GPIO, ADC |
| 18 | 15 | IO15GPIO15 | strapping | adc | GPIO, ADC |
| 19 | 16 | IO16GPIO16 | strapping | - | GPIO |
| 20 | 17 | IO17GPIO17 | safe | - | GPIO |
| 21 | 18 | IO18GPIO18 | safe | - | GPIO |
| 22 | 21 | IO21GPIO21 | safe | - | GPIO |
| 23 | 33 | IO33GPIO33 | safe | adc | GPIO, ADC |
| 24 | 34 | IO34GPIO34 | safe | adc | GPIO, ADC |
| 25 | 35 | IO35GPIO35 | safe | adc | GPIO, ADC |
| 26 | 36 | IO36GPIO36 | safe | adc | GPIO, ADC |
| 27 | 37 | IO37GPIO37 | safe | adc | GPIO, ADC |
| 28 | 38 | IO38GPIO38 | safe | adc | GPIO, ADC |
| 29 | 39 | IO39GPIO39 | strapping | adc | GPIO, ADC |
| 30 | 40 | IO40GPIO40 | strapping | adc | GPIO, ADC |
| 31 | - | EN | control | - | Chip enable / reset (active LOW) - the same net as the RST button |
| 32 | - | GND | ground | - | Ground connection |
Start with these
17 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
10 pins · 5 things to knowIO9IO10IO11IO12IO13IO14 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 does not restrict it, so it is only taken if your board wires flash, an SD card or a display to FSPI.
- IO9General-purpose SPI2 (FSPI) IO MUX pin - hold/data line (FSPIHD)
- IO10General-purpose SPI2 (FSPI) IO MUX pin - chip select (FSPICS0)
- IO11General-purpose SPI2 (FSPI) IO MUX pin - data in (FSPID)
- IO12General-purpose SPI2 (FSPI) IO MUX pin - clock (FSPICLK)
- IO13General-purpose SPI2 (FSPI) IO MUX pin - data out (FSPIQ)
- IO14General-purpose SPI2 (FSPI) IO MUX pin - write-protect/data line (FSPIWP)
IO15 32.768 kHz RTC crystal oscillator positive input (XTAL_32K_P); also functions as GPIO15 (U0RTS, ADC2_CH4). Other
If an external 32 kHz crystal is used for RTC, this pin is dedicated to the crystal and cannot be used as GPIO.
IO16 32.768 kHz RTC crystal negative input (XTAL_32K_N); also GPIO16 (U0CTS, ADC2_CH5). Other
If using an external 32 kHz crystal, this pin is connected to the crystal and should not be used as general I/O.
IO39 JTAG test clock pin (MTCK); also usable as GPIO39 or as a clock output (CLK_OUT3). JTAG
Used for JTAG debugging interface; using this pin for other purposes will disable JTAG clock input.
IO40 JTAG test data-out pin (MTDO); also GPIO40, supports CLK_OUT2. JTAG
Part of JTAG interface (TDO); should be avoided as GPIO if JTAG debugging is needed.
The LOLIN S2 Mini pinout brings out 32 pins at a 2.54 mm pitch - 27 usable GPIO alongside the VBUS, GND and 3V3 power rails.
On the analog side there are 14 ADC-capable pins for sensors and battery monitoring.
If you want zero surprises, IO1, IO2, IO3, IO4 and 13 more are free of any such role - the safest first picks. 10 of the exposed pins carry boot-time or system duties on the ESP32-S2 (IO9, IO10, IO11 and 7 more).
Getting started
flash your first firmware in ~2 minutesBoard: ESP32S2 Dev Module USB CDC On Boot: Enabled Flash Size: 4MB (32Mb) Flash Mode: DIO PSRAM: QSPI PSRAM Partition Scheme: Default 4MB with spiffs (1.2MB APP/1.5MB SPIFFS) 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_s2_mini]
platform = espressif32
board = esp32-s2-saola-1
framework = arduino
monitor_speed = 115200
upload_speed = 921600
board_build.arduino.memory_type = qio_qspi
build_flags = -DBOARD_HAS_PSRAMesp32-s2-saola-1 - or type it after board =.esp32:
board: esp32-s2-saola-1
variant: esp32s2
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_outesp32-s2-saola-1 (same ids as PlatformIO).esptool.py --chip esp32s2 --port /dev/ttyACM0 \
--baud 921600 write_flash 0x1000 firmware.bin--port = your /dev/tty* (macOS/Linux) or COMx (Windows).Downloads
Free for non-commercial use, credit espboards.dev · License
Board illustration
The bare LOLIN S2 Mini board drawn to scale at 34.3 × 25.4 mm, with no pin labels on it. Made for slide decks, wiring diagrams and project write-ups where a photo is too busy. Take the scalable SVG for print or editing, the high-resolution PNG to drop straight in, or the transparent PNG when you need it with no background behind it.
Pinout diagram
Every pin on both sides of the board with its functions, drawn by ESPboards from the ESP32-S2 Series Datasheet v1.9 - the same sheet shown at the top of this page. The PNG is a high-resolution image for screens, the SVG is vector so it stays sharp at any size, and the PDF is laid out to print on A4 or Letter.
Yours to use, share and adapt for non-commercial work, as long as you credit espboards.dev - the full terms and ready-made credit lines are here.
Specifications
ESP32-S2 · 34.3 × 25.4 mm · vs other ESP32 chips →Dimensions
About this board
At its core is the ESP32-S2 - a single-core Xtensa with native USB-OTG and no Bluetooth.
Expect to pay about $5.00 - less than the ~$20 most ESP32-S2 boards go for.
Onboard you'll find 2MB PSRAM, status LEDs (Blue (GPIO15)) and Reset/Button (GPIO0) buttons.
It flashes over native USB - no serial-converter driver needed, which isn't a given among ESP32-S2 boards.
Where to buy
prices are typical street pricesResources
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