Adafruit Metro ESP32-S2
Full-size ESP32-S2 dev board with USB-C and STEMMA QT - great for breadboarding and secure applications.
Adafruit Metro ESP32-S2 Pinout
28 pins · 2.54 mm pitch
| Pin | GPIO | Labels | Status | Capabilities | Notes |
|---|---|---|---|---|---|
| 1 | 0 | PIN_BUTTON1 | strapping | - | |
| 2 | 1 | A2T1PWM | safe | adc · touch | |
| 3 | 2 | A3T2PWM | safe | adc · touch | |
| 4 | 3 | A4T3PWM | safe | adc · touch | |
| 5 | 4 | A5T4PWM | safe | adc · touch | |
| 6 | 5 | TXA6T5PWM | uart | adc · touch · uart | |
| 7 | 6 | RXA7T6PWM | uart | adc · touch · uart | |
| 8 | 7 | A8T7PWM | safe | adc · touch | |
| 9 | 8 | A9T8PWM | safe | adc · touch | |
| 10 | 9 | A10T9PWM | strapping | adc · touch | |
| 11 | 10 | A11T10PWM | strapping | adc · touch | |
| 12 | 11 | A12T11PWM | strapping | adc · touch | |
| 13 | 12 | A13T12PWM | strapping | adc · touch | |
| 14 | 13 | A14T13PWM | strapping | adc · touch | |
| 15 | 14 | A15T14PWM | strapping | adc · touch | |
| 16 | 15 | A16PWM | strapping | adc | |
| 17 | 16 | A17PWM | strapping | adc | |
| 18 | 17 | A0DAC1PWM | safe | adc · dac | |
| 19 | 18 | A1DAC2PWM | safe | adc · dac | |
| 20 | 19 | A18PWM | uart | adc | |
| 21 | 20 | A19PWM | uart | adc | |
| 22 | 33 | SDAPWM | safe | i2c | |
| 23 | 34 | SCLPWM | safe | i2c | |
| 24 | 35 | MOSIPWM | safe | spi | |
| 25 | 36 | SCKPWM | safe | spi | |
| 26 | 37 | MISOPWM | safe | spi | |
| 27 | 42 | LED_BUILTINSSPWM | strapping | spi | |
| 28 | 45 | PIN_NEOPIXELPWM | strapping | - |
Start with these
15 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
11 pins · 6 things to knowPIN_BUTTON1GPIO0 Bootstrapping pin; selects boot mode (SPI Boot vs UART Download). Strapping
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.
A10GPIO9A11GPIO10A12GPIO11A13GPIO12A14GPIO13A15GPIO14 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.
- A10General-purpose SPI2 (FSPI) IO MUX pin - hold/data line (FSPIHD)
- A11General-purpose SPI2 (FSPI) IO MUX pin - chip select (FSPICS0)
- A12General-purpose SPI2 (FSPI) IO MUX pin - data in (FSPID)
- A13General-purpose SPI2 (FSPI) IO MUX pin - clock (FSPICLK)
- A14General-purpose SPI2 (FSPI) IO MUX pin - data out (FSPIQ)
- A15General-purpose SPI2 (FSPI) IO MUX pin - write-protect/data line (FSPIWP)
A16GPIO15 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.
A17GPIO16 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.
LED_BUILTINGPIO42 JTAG test mode select pin (MTMS); also GPIO42. JTAG
JTAG TMS pin; should not be repurposed if JTAG debugging or programming via JTAG is required.
PIN_NEOPIXELGPIO45 Bootstrapping pin; selects flash supply voltage (VDD_SPI) (0 = 3.3 V, 1 = 1.8 V). Strapping
Must be set correctly at boot (usually low for 3.3 V); improper level can cause boot failure or flash malfunction.
Only if you know the tricks
2 pins · 2 things to knowA18GPIO19 USB OTG D- line (full-speed USB data -); also available as GPIO19/RTC_GPIO19 and ADC2 channel 8. USB
Used for USB communication; using this pin as general GPIO can interfere with USB functionality.
A19GPIO20 USB OTG D+ line (full-speed USB data +); also serves as GPIO20/RTC_GPIO20 and ADC2 channel 9. USB
Dedicated to USB interface; repurposing as GPIO may disrupt USB connectivity.
All 28 pins on the Adafruit Metro ESP32-S2 are usable GPIO, spaced at the standard 2.54 mm pitch.
Peripheral wiring is straightforward: I²C is mapped to SDA on GPIO33 and SCL on GPIO34; the SPI bus (MOSI, MISO, SCK, SS) is broken out in full; TX/RX on GPIO5 and GPIO6 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.
11 of the exposed pins carry boot-time or system duties on the ESP32-S2 (PIN_BUTTON1, A10, A11 and 8 more) - check the guidance above before wiring anything to them. A2, A3, A4, A5 and 11 more are free of any such role - the safest first picks.
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:adafruit_metro_esp32s2]
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).Specifications
ESP32-S2 · 72 × 53.2 mm · vs other ESP32 chips →Dimensions
About this board
Inside sits the ESP32-S2 - a single-core Xtensa with native USB-OTG and no Bluetooth.
At $24.95 it's on the expensive side for an ESP32-S2 board - most land around $20.
Around the module: 2MB (QSPI) PSRAM, a STEMMA QT connector, an addressable RGB LED (GPIO45), a battery fuel gauge (MAX17048), battery charging via JST-PH 2.0, status LEDs (On, Charge, User) and Reset/DFU (BOOT0) 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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