ESP32-S2 Mini Pinout

Overview

The S2 Mini is a compact ESP32-S2 development board made by WEMOS/Lolin, with onboard USB-C, a reset button, a 3.3V regulator, and 29 accessible GPIOs across two header rows. The ESP32-S2 is Espressif’s Wi-Fi-only chip, no Bluetooth, no 802.15.4, which makes it a good fit for USB-powered sensors and gadgets that don’t need a second radio.

No Bluetooth badge here on purpose: unlike every other chip in these guides, the ESP32-S2 genuinely has no Bluetooth radio at all, not even BLE.

Getting started

The S2 Mini uses the chip’s native USB peripheral directly, not a separate USB-to-serial chip, so no extra USB driver is usually needed on modern operating systems.

Hello World: blink an LED

The microcontroller equivalent of “Hello World”: GPIO21 toggles once a second, shown here in two different environments. Wire an LED (with a resistor) to GPIO21, a plain general-purpose pin with no other job on this board.

#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "driver/gpio.h"

#define LED_PIN GPIO_NUM_21

void app_main(void)
{
    gpio_reset_pin(LED_PIN);
    gpio_set_direction(LED_PIN, GPIO_MODE_OUTPUT);

    while (1) {
        gpio_set_level(LED_PIN, 1);
        vTaskDelay(pdMS_TO_TICKS(1000));
        gpio_set_level(LED_PIN, 0);
        vTaskDelay(pdMS_TO_TICKS(1000));
    }
}

#define LED_PIN 21

void setup() {
  pinMode(LED_PIN, OUTPUT);
}

void loop() {
  digitalWrite(LED_PIN, HIGH);
  delay(1000);
  digitalWrite(LED_PIN, LOW);
  delay(1000);
}

ESP-IDF: build and flash with idf.py build flash monitor. Arduino IDE: install ESP32 board support first, see “Getting started” above.

Specifications

Official specifications for the ESP32-S2 chip and the S2 Mini board.

Pinout diagram

The full S2 Mini layout, including the alternate ADC1/ADC2/touch/JTAG functions on each pin.

GPIO quick reference

GPIO19 and GPIO20 are the chip’s native USB D+/D− pins and aren’t broken out on this board, they’re not listed below.

Flashing pins

The S2 Mini flashes over its native USB port, not a separate UART bridge, so there’s no TXD0/RXD0 pin pair to route externally.

Safety notes