Unexpected Maker FeatherS3 Development Board (FeatherS3)
Unexpected Maker FeatherS3

Available from:


Install method:
USB to Serial

GPIO #Component
Configuration for ESP32-S3

A Feather form factor ESP32-S3 dev board with 1S LiPo battery monitoring.

This board uses an ESP32-S3 chip with no onboard flash or PSRAM with an external 16 MB SPI flash chip and an external 8MB PSRAM chip.

When the board is booted into debug by holding BOOT and pressing the RESET button the USB-Serial chip on the USB port exposes a serial connection. This can be used to easily flash new firmware.


Flash using Tasmota Web Installer and select Tasmota ESP32-S3 option.

For esptool.py download f.e. tasmota32s3.factory.bin and run esptool.py write_flash 0x0 tasmota32s3.factory.bin

To put ESP32-S3 in flash mode GPIO0 needs to be pulled low.

Device Notes

Unexpected Maker FeatherS3 Front

Unexpected Maker FeatherS3 Pinout

FeatherS3 Schematic


  • WS2812B Neopixel
    • On GPIO40 (configured as WS2812) with power on GPIO39 (configured as Output Hi).
  • 1x Blue Status LED
    • On GPIO13 (configured as LED 1).
  • 1x Ambient light sensor (ALS-PT19)
    • On GPIO4 (configured as Analog2).
  • 2x STEMMA-QT JST-SH I2C bus connector
    • Both ports share the same bus, on GPIO9 (SCL) and GPIO8 (SDA) (configured as I2C 1). These ports are on the same bus as the SCL and SDA pins labelled on the board.
  • 1S LiPo battery management subsystem with 2-pin JST-PH connector
    • Battery voltage divider on GPIO2 (configured as Analog1) and 5V/USB voltage detection on GPIO34 (not configured)

GPIO Pin Mapping

The user pins labelled on the board are set up as User pins in the template.The pin numbers match the ESP’s internal GPIO number assignments allowing relatively easy module configuration without having to translate pin.

The only exception are the pins labeled TX and RX, which are set up as Serial TX/RX in the template.