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LOLIN S2 Mini is a development board based on the ESP32S2 microcontroller using XTENSA architecture.
This board features a maximum CPU frequency of 240 MHz and 4MB flash memory.
About LOLIN S2 Mini
Compact ESP32-S2 board by Wemos with USB-C and LiPo charging - perfect for space-saving embedded builds.
Where to Buy LOLIN S2 Mini
Starting from
5$ per unit
Prices are subject to change. We earn from qualifying purchases as an Amazon Associate.
LOLIN S2 Mini Technical Specifications
🛰️ Connectivity
WiFi: 802.11 b/g/n 2.4 GHz
Bluetooth: -
BLE: -
🧠 Microcontroller
Model: esp32s2
Clock Speed: 240 MHz
Flash Size: 4MB
Architecture: xtensa
✨ Features
- 48 digital IO pins
- 46 external interrupt pins
- 20 analog input pins
- 24 PWM pins
LOLIN S2 Mini Pinout
Safe Pins to Use
For general GPIO usage, these are the safest and most flexible choices:
IO1
IO2
IO3
IO4
IO5
IO6
IO7
IO8
IO17
IO18
IO21
Why Are These Pins Safe?
- • Not involved in bootstrapping → No impact on device boot mode or system startup
- • Not linked to flash memory or PSRAM → Won't interfere with storage or memory access
- • Not dedicated to USB or JTAG → Free for general use without affecting debugging
- • No special hardware connections → Freely assignable without internal conflicts
Pins to Avoid or Use with Caution
Some pins are reserved for critical functions like bootstrapping, JTAG debugging, USB communication, and flash memory operations. Misusing these pins may lead to boot failures, programming issues, USB conflicts, or disruptions in flash storage.
Critical Pin Categories:
- Strapping Pins: Control boot behavior and flash voltage selection
- JTAG Debugging Pins: Required for low-level debugging
- USB Communication Pins: Used for USB Serial/JTAG communication
- Flash Memory & SPI Pins: Connected to SPI flash memory and PSRAM
- UART Serial Communication Pins: Used for debugging and firmware uploads
| PIN | Label | Reason | Function |
|---|---|---|---|
| IO9 | FSPIHD | Typically used as flash/PSRAM IO line in certain configurations; avoid using as GPIO if flash or PSRAM is present. | ⚡ Flash |
| IO10 | FSPICS0 | Often used as flash chip select in some designs; not available for GPIO when controlling flash. | ⚡ Flash |
| IO11 | FSPID | Used for flash data transfer in certain configurations; should be avoided for general use if flash is connected. | ⚡ Flash |
| IO12 | FSPICLK | Used as flash clock line in some boards; not free for GPIO if driving flash. | ⚡ Flash |
| IO13 | FSPIQ | Used for flash data output in certain configurations; avoid using as GPIO if connected to flash. | ⚡ Flash |
| IO14 | FSPIWP | Used as flash write-protect/data line on some modules; not recommended for other usage. | ⚡ Flash |
| IO15 | XTAL_32K_P | If an external 32 kHz crystal is used for RTC, this pin is dedicated to the crystal and cannot be used as GPIO. | 🪛 Other |
| IO16 | XTAL_32K_N | If using an external 32 kHz crystal, this pin is connected to the crystal and should not be used as general I/O. | 🪛 Other |
| IO33 | SPIHD | Connected to SPI flash (hold/data line); not available for general-purpose use. | ⚡ Flash |
| IO34 | SPIWP | Connected to SPI flash (write-protect/data line); not recommended for other use. | ⚡ Flash |
| IO35 | FSPID | Used by internal flash/PSRAM on some ESP32-S2 variants; avoid using as GPIO to prevent conflicts. | ⚡ Flash |
| IO36 | FSPICLK | May be connected to internal flash or used for high-speed SPI; not intended for general GPIO use. | ⚡ Flash |
| IO37 | FSPIQ | Used for internal flash/PSRAM data in some models; should not be repurposed for GPIO. | ⚡ Flash |
| IO38 | FSPIWP | Reserved for flash/PSRAM in ESP32-S2 modules with internal memory; not recommended for general I/O. | ⚡ Flash |
| IO39 | MTCK | Used for JTAG debugging interface; using this pin for other purposes will disable JTAG clock input. | 🪛 Other |
| IO40 | MTDO | Part of JTAG interface (TDO); should be avoided as GPIO if JTAG debugging is needed. | 🪛 Other |
LOLIN S2 Mini Useful Links
LOLIN S2 Mini Custom Pins
This development board provides 48 digital IO pins, out of which 46 can be used as external interrupt pins , 20 as analog input pins and 24 pins have Pulse-Width Modulation (PWM).
| Pin | Function | ESP Pin | Input/Output | Description |
|---|---|---|---|---|
| 1 | 5V | 5V | POWER INPUT | 5V power input for the board |
| 2 | GND | GND | POWER GROUNT | Ground connection |
| 3 | 3V3 | 3.3V | POWER OUTPUT | 3.3V power output |
| 5 | IO1 | GPIO1 | BIDIRECTIONAL | GPIO |
| 6 | IO2 | GPIO2 | BIDIRECTIONAL | GPIO, ADC |
| 7 | IO3 | GPIO3 | BIDIRECTIONAL | GPIO |
| 8 | IO4 | GPIO4 | BIDIRECTIONAL | GPIO, ADC |
| 9 | IO5 | GPIO5 | BIDIRECTIONAL | GPIO |
| 10 | IO6 | GPIO5 | BIDIRECTIONAL | GPIO |
| 11 | IO7 | GPIO5 | BIDIRECTIONAL | GPIO |
| 12 | IO8 | GPIO5 | BIDIRECTIONAL | GPIO |
| 13 | IO9 | GPIO5 | BIDIRECTIONAL | GPIO |
| 14 | IO10 | GPIO5 | BIDIRECTIONAL | GPIO |
| 15 | IO11 | GPIO5 | BIDIRECTIONAL | GPIO |
| 16 | IO12 | GPIO12 | BIDIRECTIONAL | GPIO, ADC |
| 17 | IO13 | GPIO13 | BIDIRECTIONAL | GPIO, ADC |
| 18 | IO14 | GPIO14 | BIDIRECTIONAL | GPIO, ADC |
| 19 | IO15 | GPIO15 | BIDIRECTIONAL | GPIO, ADC |
| 20 | IO16 | GPIO16 | BIDIRECTIONAL | GPIO |
| 21 | IO17 | GPIO17 | BIDIRECTIONAL | GPIO |
| 22 | IO18 | GPIO18 | BIDIRECTIONAL | GPIO |
| 23 | IO21 | GPIO21 | BIDIRECTIONAL | GPIO |
| 24 | IO33 | GPIO33 | BIDIRECTIONAL | GPIO, ADC |
| 25 | IO34 | GPIO34 | INPUT | GPIO, ADC |
| 26 | IO35 | GPIO35 | INPUT | GPIO, ADC |
| 27 | IO36 | GPIO36 | INPUT | GPIO, ADC |
| 28 | IO37 | GPIO37 | INPUT | GPIO, ADC |
| 29 | IO38 | GPIO38 | INPUT | GPIO, ADC |
| 30 | IO39 | GPIO39 | INPUT | GPIO, ADC |
| 31 | IO40 | GPIO40 | INPUT | GPIO, ADC |
Function Pin Function
ESP Pin Pin on ESP32
I/O Input/Output Pin
Description Pin Description
LOLIN S2 Mini Pin Mappings
Below you can find the LOLIN S2 Mini pinout. This development board provides 48 digital IO pins, out of which 46 can be used as external interrupt pins, 20 as analog input pins and 24 pins have Pulse-Width Modulation (PWM).
| Pin | Analog | Touch | PWM | Other |
|---|---|---|---|---|
| 1 | A0 | T1 | PWM | |
| 2 | A1 | T2 | PWM | |
| 3 | A2 | T3 | PWM | |
| 4 | A3 | T4 | PWM | |
| 5 | A4 | T5 | PWM | |
| 6 | A5 | T6 | PWM | |
| 7 | A6 | T7 | PWM | SCK |
| 8 | A7 | T8 | PWM | |
| 9 | A8 | T9 | PWM | MISO |
| 10 | A9 | T10 | PWM | |
| 11 | A10 | T11 | PWM | MOSI |
| 12 | A11 | T12 | PWM | SS |
| 13 | A12 | T13 | PWM | |
| 14 | A13 | T14 | PWM | |
| 15 | A14 | PWM | LED_BUILTIN | |
| 16 | A15 | PWM | ||
| 17 | A16 | PWM | DAC1 | |
| 18 | A17 | PWM | DAC2 | |
| 19 | A18 | PWM | ||
| 20 | A19 | PWM | ||
| 33 | PWM | SDA | ||
| 35 | PWM | SCL | ||
| 37 | PWM | RX | ||
| 39 | PWM | TX | ||
| 0x00000000 | USB_FW_MSC_SERIAL_NUMBER |
Analog Analog input pins
Touch Touch pins
PWM Pulse-Width Modulation
RX / TX Receive/Transmit
LED_BUILTIN Built-in LED
Function Other functions
Default Tools for LOLIN S2 Mini
| Bootloader tool | esptool_py |
| Uploader tool | esptool_py |
| Network uploader tool | esp_ota |
| Bootloader address | 0x1000 |
| Flash mode | dio |
| Boot mode | qio |
| Maximum upload size | 1280 Kb (1310720 B) |
| Maximum data size | 320 Kb (327680 B) |
The LOLIN S2 Mini development board by default uses esptool_py uploader tool, network uploader tool for Over-the-air (OTA) uploads and esptool_py bootloader tool. The bootloader starts at address "0x1000". Flash mode and boot mode for LOLIN S2 Mini development board by default is dio and qio respectively.
