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UM FeatherS2
Feature-rich ESP32-S2 Feather board with 16MB Flash, 8MB PSRAM, and LiPo charging - great for advanced IoT projects.
52.4 × 22.6 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 | 1 | A0T1PWM | safe | adc · touch | |
| 2 | 2 | A1T2PWM | safe | adc · touch | |
| 3 | 3 | A2T3PWM | safe | adc · touch | |
| 4 | 4 | A3T4PWM | safe | adc · touch | |
| 5 | 5 | A4T5PWM | safe | adc · touch | |
| 6 | 6 | A5T6PWM | safe | adc · touch | |
| 7 | 7 | A6T7PWM | safe | adc · touch | |
| 8 | 8 | SDAA7T8PWM | safe | adc · touch · i2c | |
| 9 | 9 | SCLA8T9PWM | strapping | adc · touch · i2c | |
| 10 | 10 | A9T10PWM | strapping | adc · touch | |
| 11 | 11 | A10T11PWM | strapping | adc · touch | |
| 12 | 12 | A11T12PWM | strapping | adc · touch | |
| 13 | 13 | A12T13PWM | strapping | adc · touch | |
| 14 | 14 | A13T14PWM | strapping | adc · touch | |
| 15 | 15 | A14PWM | strapping | adc | |
| 16 | 16 | A15PWM | strapping | adc | |
| 17 | 17 | A16DAC1PWM | safe | adc · dac | |
| 18 | 18 | A17DAC2PWM | safe | adc · dac | |
| 19 | 19 | A18PWM | uart | adc | |
| 20 | 20 | A19PWM | uart | adc | |
| 21 | 21 | LDO_2_POWERPWM | safe | - | |
| 22 | 34 | SSPWM | strapping | spi | |
| 23 | 35 | MOSISDOPWM | strapping | spi | |
| 24 | 36 | SCKPWM | strapping | spi | |
| 25 | 37 | MISOSDIPWM | strapping | spi | |
| 26 | 40 | APA_DATAPWM | strapping | - | |
| 27 | 43 | TXPWM | uart | uart | |
| 28 | 44 | RXPWM | uart | uart | |
| 29 | 45 | APA_CLKPWM | strapping | - |
Start with these
13 pins with no boot or system involvementA0T1A1T2A2T3A3T4A4T5A5T6A6T7SDAA7A16DAC1A17DAC2LDO_2_POWERPWMTXPWMRXPWM
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 |
|---|---|---|---|
| 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 |
| APA_DATA | MTDO | Part of JTAG interface (TDO); should be avoided as GPIO if JTAG debugging is needed. | Other |
| APA_CLK | GPIO45 | Must be set correctly at boot (usually low for 3.3 V); improper level can cause boot failure or flash malfunction. | Strapping |
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 |
| 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 The UM FeatherS2 pinout brings out 29 GPIO pins at a 2.54 mm pitch - every one of them usable in your project. For peripherals, I²C is mapped to SDA on GPIO8…
The UM FeatherS2 pinout brings out 29 GPIO pins at a 2.54 mm pitch - every one of them usable in your project.
For peripherals, 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.
On the analog side there are 20 ADC-capable pins for sensors and battery monitoring, 14 capacitive-touch inputs and 2 true DAC outputs.
If you want zero surprises, A0, A1, A2, A3 and 9 more are free of any such role - the safest first picks. 4 of the exposed pins carry boot-time or system duties on the ESP32-S2 (A14, A15, APA_DATA and 1 more).
Getting started
flash your first firmware in ~2 minutes1
Connect over USB
Native USB - shows up as a port right away, no driver needed. Not detected? Hold BOOT while plugging in.
2
Match & flash
Set the Tools options shown, then click Upload.
3
Verify it runs
The onboard LED on GPIO1 blinks - swap the pin if your board's LED differs.
Set these in Tools · leave everything else at default
Arduino IDE 2.x — Tools Copy
Board: "ESP32S2 Dev Module"▸
USB CDC On Boot: "Enabled"▸
Flash Size: "16MB (128Mb)"▸
Flash Mode: "DIO"▸
PSRAM: "QSPI PSRAM"▸
Partition Scheme: "16M Flash (3MB APP / 9.9MB FATFS)" (default)▸
Upload Speed: "921600"▸
▸ every other Tools option — leave at default
Board: ESP32S2 Dev Module USB CDC On Boot: Enabled Flash Size: 16MB (128Mb) Flash Mode: DIO PSRAM: QSPI PSRAM Partition Scheme: 16M Flash (3MB APP / 9.9MB FATFS) Upload Speed: 921600
Find it: Tools ▸ Board ▸ ESP32 Arduino ▸ ESP32S2 Dev Module
// blink the onboard LED
void setup() {
pinMode(1, OUTPUT);
}
void loop() {
digitalWrite(1, HIGH); delay(500);
digitalWrite(1, LOW); delay(500);
}board to selectesp32-s2-saola-1⧉ copy
[env:feathers2]
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_PSRAMFind it: PlatformIO Home ▸ Boards, search
esp32-s2-saola-1 — or type it after board =.board to selectesp32-s2-saola-1⧉ copy
esp32:
board: esp32-s2-saola-1
variant: um_feathers2
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_outFind it: search ESPHome's board list for
esp32-s2-saola-1 (same ids as PlatformIO).esptool doesn't pick board settings — a prebuilt .bin already has them baked in. This is just the raw flash command.
esptool.py --chip esp32s2 --port /dev/ttyACM0 \
--baud 921600 write_flash 0x0 firmware.bin--port = your /dev/tty* (macOS/Linux) or COMx (Windows).Build details: sketch space 1310720 B · data 327680 B · DIO
Specifications
ESP32-S2 · 52.4 × 22.6 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
3D
I/O
GPIO · ADC
29 · 20
UART · I²C · SPI
2 · 1 · 4
PWM
8 channels
Power
USB
USB-C
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
52.4 × 22.6 mm · pin pitch 2.54 mm
The UM FeatherS2 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
At its core is the ESP32-S2 - a single-core Xtensa with native USB-OTG and no Bluetooth.
Expect to pay about $24.95 - above the ~$20 typical for ESP32-S2 boards.
Onboard you'll find 8MB (QSPI) PSRAM, a STEMMA QT connector, an ambient-light sensor (ALS-PT19), battery charging (MCP73831) via JST-PH 2.0, status LEDs (Blue user (GPIO13), Charge) and Reset/Boot buttons.
It flashes over native USB - no serial-converter driver needed, which isn't a given among ESP32-S2 boards.
- APA102 DotStar RGB LED (DATA GPIO40, CLK GPIO45)
- 2x 700mA 3.3V LDO regulators (second LDO powers the RGB LED & light sensor)
Where to buy
prices are typical street pricesUM FeatherS2
$24.95per unit, typical
Resources
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