UM FeatherS2
Feature-rich ESP32-S2 Feather board with 16MB Flash, 8MB PSRAM, and LiPo charging - great for advanced IoT projects.
UM FeatherS2 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 | safe | spi | |
| 23 | 35 | MOSISDOPWM | safe | spi | |
| 24 | 36 | SCKPWM | safe | spi | |
| 25 | 37 | MISOSDIPWM | safe | spi | |
| 26 | 40 | APA_DATAPWM | strapping | - | |
| 27 | 43 | TXPWM | uart | uart | |
| 28 | 44 | RXPWM | uart | uart | |
| 29 | 45 | APA_CLKPWM | strapping | - |
Start with these
17 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
10 pins · 5 things to knowSCLGPIO9A9GPIO10A10GPIO11A11GPIO12A12GPIO13A13GPIO14 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.
- SCLGeneral-purpose SPI2 (FSPI) IO MUX pin - hold/data line (FSPIHD)
- A9General-purpose SPI2 (FSPI) IO MUX pin - chip select (FSPICS0)
- A10General-purpose SPI2 (FSPI) IO MUX pin - data in (FSPID)
- A11General-purpose SPI2 (FSPI) IO MUX pin - clock (FSPICLK)
- A12General-purpose SPI2 (FSPI) IO MUX pin - data out (FSPIQ)
- A13General-purpose SPI2 (FSPI) IO MUX pin - write-protect/data line (FSPIWP)
A14GPIO15 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.
A15GPIO16 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.
APA_DATAGPIO40 JTAG test data-out pin (MTDO); also GPIO40, supports CLK_OUT2. JTAG
Part of JTAG interface (TDO); should be avoided as GPIO if JTAG debugging is needed.
APA_CLKGPIO45 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.
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 13 more are free of any such role - the safest first picks. 10 of the exposed pins carry boot-time or system duties on the ESP32-S2 (SCL, A9, A10 and 7 more).
Getting started
flash your first firmware in ~2 minutesBoard: 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
// 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: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_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 · 52.4 × 22.6 mm · vs other ESP32 chips →Dimensions
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 pricesResources
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