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microS2
Tiny ESP32-S2 board with USB-C and low power - great for portable, secure IoT projects and embedded prototypes.
31 × 18 mm
ESP32-S2
MCU
240MHz
clock
16MB
flash
320KB
SRAM
29· 20 ADC
GPIO
Wi-Fi
radio
Pinout
29 pins · 2.54 mm pitch| Pin | GPIO | Labels | Status | Capabilities | Notes |
|---|---|---|---|---|---|
| 1 | 0 | BUTTON_BUILTIN | strapping | - | |
| 2 | 1 | A0T1PWM | safe | adc · touch | |
| 3 | 2 | A1T2PWM | safe | adc · touch | |
| 4 | 3 | A2T3PWM | safe | adc · touch | |
| 5 | 4 | A3T4PWM | safe | adc · touch | |
| 6 | 5 | A4T5PWM | safe | adc · touch | |
| 7 | 6 | A5T6PWM | safe | adc · touch | |
| 8 | 7 | A6T7PWM | safe | adc · touch | |
| 9 | 8 | SDAA7T8PWM | safe | adc · touch · i2c | |
| 10 | 9 | SCLA8T9PWM | strapping | adc · touch · i2c | |
| 11 | 10 | A9T10PWM | strapping | adc · touch | |
| 12 | 11 | A10T11PWM | strapping | adc · touch | |
| 13 | 12 | A11T12PWM | strapping | adc · touch | |
| 14 | 13 | A12T13PWM | strapping | adc · touch | |
| 15 | 14 | A13T14PWM | strapping | adc · touch | |
| 16 | 15 | A14PWM | strapping | adc | |
| 17 | 16 | A15PWM | strapping | adc | |
| 18 | 17 | A16DAC1PWM | safe | adc · dac | |
| 19 | 18 | A17DAC2PWM | safe | adc · dac | |
| 20 | 19 | A18PWM | uart | adc | |
| 21 | 20 | A19PWM | uart | adc | |
| 22 | 21 | LED_BUILTINPWM | safe | - | |
| 23 | 33 | PIXEL_BUILTINPWM | strapping | - | |
| 24 | 34 | SSPWM | strapping | spi | |
| 25 | 35 | MOSISDOPWM | strapping | spi | |
| 26 | 36 | SCKPWM | strapping | spi | |
| 27 | 37 | MISOSDIPWM | strapping | spi | |
| 28 | 43 | TXPWM | uart | uart | |
| 29 | 44 | RXPWM | uart | uart |
Start with these
13 pins with no boot or system involvementA0T1A1T2A2T3A3T4A4T5A5T6A6T7SDAA7A16DAC1A17DAC2LED_BUILTINPWMTXPWMRXPWM
Freely assignable - no strapping, flash, USB or JTAG duties. Ideal first picks for buttons, sensors and LEDs.
Fine - with a little care
sampled at boot or shared with debug/serial| Pin | Label | What to know | Role |
|---|---|---|---|
| BUTTON_BUILTIN | GPIO0 | Must be pulled high for normal boot; pulling low at reset enters bootloader (download mode). Also serves as SPI flash data-in (SPID) line when using external flash memory. | Strapping |
| A14 | 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 |
| A15 | 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 |
Only if you know the tricks
wired to flash or USB - expect a fight| Pin | Label | What to know | Role |
|---|---|---|---|
| SCL | FSPIHD | Typically used as flash/PSRAM IO line in certain configurations; avoid using as GPIO if flash or PSRAM is present. | Flash |
| A9 | FSPICS0 | Often used as flash chip select in some designs; not available for GPIO when controlling flash. | Flash |
| A10 | FSPID | Used for flash data transfer in certain configurations; should be avoided for general use if flash is connected. | Flash |
| A11 | FSPICLK | Used as flash clock line in some boards; not free for GPIO if driving flash. | Flash |
| A12 | FSPIQ | Used for flash data output in certain configurations; avoid using as GPIO if connected to flash. | Flash |
| A13 | FSPIWP | Used as flash write-protect/data line on some modules; not recommended for other usage. | Flash |
| A18 | USB_D- | Used for USB communication; using this pin as general GPIO can interfere with USB functionality. | USB |
| A19 | USB_D+ | Dedicated to USB interface; repurposing as GPIO may disrupt USB connectivity. | USB |
| PIXEL_BUILTIN | SPIHD | Connected to SPI flash (hold/data line); not available for general-purpose use. | Flash |
| SS | SPIWP | Connected to SPI flash (write-protect/data line); not recommended for other use. | Flash |
| MOSI | FSPID | Used by internal flash/PSRAM on some ESP32-S2 variants; avoid using as GPIO to prevent conflicts. | Flash |
| SCK | FSPICLK | May be connected to internal flash or used for high-speed SPI; not intended for general GPIO use. | Flash |
| MISO | FSPIQ | Used for internal flash/PSRAM data in some models; should not be repurposed for GPIO. | Flash |
These are recommendations, not hard rules - with the right pull-ups, timing and boot-state awareness most pins can be made to work. When in doubt, start green.
Pinout notes All 29 pins on the microS2 are usable GPIO, spaced at the standard 2.54 mm pitch. Peripheral wiring is straightforward: I²C is mapped to SDA on GPIO8 and SCL…
All 29 pins on the microS2 are usable GPIO, spaced at the standard 2.54 mm pitch.
Peripheral wiring is straightforward: I²C is mapped to SDA on GPIO8 and SCL on GPIO9; 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 20 ADC-capable pins for sensors and battery monitoring, 14 capacitive-touch inputs and 2 true DAC outputs.
3 of the exposed pins carry boot-time or system duties on the ESP32-S2 (BUTTON_BUILTIN, A14 and A15) - check the guidance above before wiring anything to them. A0, A1, A2, A3 and 9 more are free of any such role - the safest first picks.
Getting started
flash your first firmware in ~2 minutes1
Connect over USB
Native USB - no driver, no serial chip. Not detected? Hold BOOT while plugging in.
2
Flash with your tool
Arduino IDE, PlatformIO, ESPHome or esptool - copy the settings on the right.
3
Verify it runs
The blink example uses GPIO1 - swap for your board's LED pin if different.
Board: Micros2
USB CDC On Boot: Enabled
Flash Size: 16MB · DIO
Upload Speed: 921600
// blink
pinMode(1, OUTPUT);
digitalWrite(1, LOW); // on (often inverted)[env:micros2]
platform = espressif32
board = esp32-s2-saola-1
framework = arduino
monitor_speed = 115200
upload_speed = 921600esp32:
board: esp32-s2-saola-1
variant: micro_s2
framework:
type: esp-idf
# blink - GPIO1
output:
- platform: gpio
pin: 1
id: led_out
light:
- platform: binary
name: "LED"
output: led_outesptool.py --chip esp32s2 --port /dev/ttyACM0 \
write_flash 0x0 firmware.binBuild details: sketch space 1310720 B · data 327680 B · DIO
Specifications
ESP32-S2 · 31 × 18 mmCompute
MCU
ESP32-S2
Clock
240 MHz
SRAM · Flash
320 KB · 16MB · 8MB (QSPI) PSRAM
Radio
Wi-Fi
802.11 b/g/n 2.4 GHz
Bluetooth
-
Antenna
Ceramic
I/O
GPIO · ADC
29 · 20
UART · I²C · SPI
2 · 1 · 4
PWM
8 channels
Power
USB
Micro-USB
Serial
Native (CDC)
Boot address
0x1000
Flashing
Upload · OTA
esptool_py · esp_ota
Flash · Boot mode
DIO · QIO
Sketch · Data
1.25 MB · 320 KB
31 × 18 mm · pin pitch 2.54 mm
The microS2 uses esptool_py for firmware uploads, esp_ota for over-the-air (OTA) updates. Flash mode is DIO with QIO boot mode. The maximum sketch size is 1.25 MB with 320 KB available for data.
About this board
Inside sits the ESP32-S2 - a single-core Xtensa with native USB-OTG and no Bluetooth.
Around the module: 8MB (QSPI) PSRAM, a Qwiic connector, an addressable RGB LED (GPIO33), status LEDs (Blue) and Reset/Boot buttons.
It flashes over native USB - no serial-converter driver needed, which isn't a given among ESP32-S2 boards.
Resources
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