Feather-format STM32F405 Cortex-M4 board at 168 MHz with 1 MB flash, 192 KB RAM, 2 MB SPI flash, SD socket (SDIO), STEMMA QT, USB-C, and LiPo charger. Uses DFU bootloader instead of UF2; Arduino IDE setup requires manual BOOT0 steps.
Common ground for all power and logic on the Feather STM32F405 Express board.
Positive voltage to/from the JST jack for the optional LiPoly battery.
Positive voltage to/from the USB-C jack when connected.
3.3V regulator enable pin; pulled up, connect to ground to disable the 3.3V regulator.
Output from the 3.3V regulator for board/peripheral power.
UART receive pin for Serial3; also general-purpose 3.3V logic I/O.
UART transmit pin for Serial3; also general-purpose 3.3V logic I/O.
I2C Wire data pin with 10K pull-up to 3.3V; hardware I2C1.
I2C Wire clock pin with 10K pull-up to 3.3V; hardware I2C1.
Main SPI bus clock pin, hardware SPI2.
Main SPI bus input data pin, hardware SPI2.
Main SPI bus output data pin, hardware SPI2.
Analogue input and DAC OUT1 true analogue output.
Analogue input and DAC OUT2 true analogue output.
Analogue input; alternate use SPI1 SCK.
Analogue input; alternate use SPI1 MISO.
JST SH STEMMA QT/Qwiic connector power rail.
JST SH STEMMA QT/Qwiic connector ground.
STEMMA QT/Qwiic connector I2C data, usable as board.SDA.
STEMMA QT/Qwiic connector I2C clock, usable as board.SCL.
On-board single NeoPixel data connection, Arduino pin #8 / board.NEOPIXEL.
| Pin | Position | Type | Function | Voltage |
|---|---|---|---|---|
| GND | ground | Common ground for all power and logic on the Feather STM32F405 Express board. | 0V reference; source states common ground for power and logic. | |
| BAT | power | Positive voltage to/from the JST jack for the optional LiPoly battery. | Battery input/output; exact battery voltage not restated on pinouts page. | |
| USB | power | Positive voltage to/from the USB-C jack when connected. | USB bus voltage; source identifies it as the USB-C positive voltage. | |
| EN | control | 3.3V regulator enable pin; pulled up, connect to ground to disable the 3.3V regulator. | 3.3V regulator enable control; pulled up per source. | |
| 3V | power | Output from the 3.3V regulator for board/peripheral power. | 3.3V output, source states it can supply 500mA peak. | |
| RX / GPIO 0 / PB11 | digital | UART receive pin for Serial3; also general-purpose 3.3V logic I/O. | 3.3V logic; source notes nearly all GPIO pins are 5V compliant. | |
| TX / GPIO 1 / PB10 | digital | UART transmit pin for Serial3; also general-purpose 3.3V logic I/O. | 3.3V logic; source notes nearly all GPIO pins are 5V compliant. | |
| SDA / GPIO 14 / PB7 | i2c | I2C Wire data pin with 10K pull-up to 3.3V; hardware I2C1. | 3.3V pull-up on SDA per source. | |
| SCL / GPIO 15 / PB6 | i2c | I2C Wire clock pin with 10K pull-up to 3.3V; hardware I2C1. | 3.3V pull-up on SCL per source. | |
| SCK / GPIO 23 | spi | Main SPI bus clock pin, hardware SPI2. | 3.3V logic; source notes nearly all GPIO pins are 5V compliant. | |
| MISO / GPIO 24 | spi | Main SPI bus input data pin, hardware SPI2. | 3.3V logic; source notes nearly all GPIO pins are 5V compliant. | |
| MOSI / GPIO 25 | spi | Main SPI bus output data pin, hardware SPI2. | 3.3V logic; source notes nearly all GPIO pins are 5V compliant. | |
| A0 / GPIO 16 / PA4 | analog | Analogue input and DAC OUT1 true analogue output. | Analogue output can be set from 0V to 3.3V per source. | |
| A1 / GPIO 17 / PA5 | analog | Analogue input and DAC OUT2 true analogue output. | Analogue output can be set from 0V to 3.3V per source. | |
| A2 / GPIO 18 / PA6 | analog | Analogue input; alternate use SPI1 SCK. | 3.3V analogue/GPIO domain; source notes general GPIO logic is 3.3V. | |
| A3 / GPIO 19 / PA7 | analog | Analogue input; alternate use SPI1 MISO. | 3.3V analogue/GPIO domain; source notes general GPIO logic is 3.3V. | |
| STEMMA QT / Qwiic 3.3V | power | JST SH STEMMA QT/Qwiic connector power rail. | 3.3V on STEMMA QT/Qwiic connector per source. | |
| STEMMA QT / Qwiic GND | ground | JST SH STEMMA QT/Qwiic connector ground. | 0V reference. | |
| STEMMA QT / Qwiic SDA | i2c | STEMMA QT/Qwiic connector I2C data, usable as board.SDA. | 3.3V I2C connector rail per source. | |
| STEMMA QT / Qwiic SCL | i2c | STEMMA QT/Qwiic connector I2C clock, usable as board.SCL. | 3.3V I2C connector rail per source. | |
| NeoPixel / GPIO 8 | digital | On-board single NeoPixel data connection, Arduino pin #8 / board.NEOPIXEL. | NeoPixel powered by the 3.3V supply per source. |
USB · 3.3 V
Confirm the data interface matches your host board.
Module pins: BAT, USB, 3V, STEMMA QT / Qwiic 3.3V, GND, STEMMA QT / Qwiic GND, SDA / GPIO 14 / PB7, SCL / GPIO 15 / PB6. Schematik maps them to your board in the app.
Specialists: Teensy for high-clock audio and USB, Adafruit SAMD boards running CircuitPython or the Arduino IDE, proper STM32 eval kits, and the micro:bit classroom ecosystem. Schematik builds target ESP32, Arduino Uno, and Pico; come here when you have a specific reason to.
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