LOLIN S2 Mini Development Board

Code name: LOLIN_S2_MINI

LOLIN S2 Mini development board is based on esp32s2 microcontroller and uses xtensa architecture. This board has a maximum CPU frequency of 240 MHz and a flash size of 4MB.

⚡ Tech Specs 📌 Pinout 🔗 Useful Links 🗺️ Mappings 🛠️ Tools

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

Starting from

5$ per unit

Amazon.com Ships worldwide

View Price

Amazon.de Ships to EU

View Price

Prices are subject to change. We earn from qualifying purchases as an Amazon Associate.

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

🔗 ESP32S2 Datasheet

https://www.espressif.com/sites/default/files/documentation/esp32-s2_datasheet_en.pdf

LOLIN S2 Mini Pin Mappings

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 Pins Mapping Arduino IDE

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

Function Function pins

RX / TX Receive/Transmit

LED_BUILTIN Built-in LED

PWM Pulse-Width Modulation

Default Tools

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, esp_ota 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.