Rev 3.0

Rev 3.0 added Qwiic I2C connectivity, a NeoPixel expansion port, PWM signal buffering for improved fan signal integrity, and a bottom SMD expansion header. Unlike Rev 3.1+, it does not have RGB status LEDs.

Front

Back

Specifications

• MCU: ESP32S2-Mini-2
• Board platform: esp32-s2-saola-1
• Power: DC Input (12V, 5.5x2.1mm)
• Flashing: USB-C port
• Fan outputs: 4x PWM headers with signal buffering
• Status LED: Red (single)
• Sensor: HDC1080 Temperature and Humidity
• Buttons: Reset, Boot, 3x User
• Expansion: QWIIC I2C, I2C port (100mil), NeoPixel port (5V, max 2A), SMD expansion header

NeoPixel framework requirement

The NeoPixel port requires the arduino framework, since GPIO42 requires use of the fastled_clockless platform, which is not supported on esp-idf.

Factory Firmware Installation

Flash Rev 3.0 Factory Firmware

USB not working?

The ESP32-S2 has known USB reliability issues. If the flash button doesn’t detect your board:

1. Try a different USB cable (data cable, not charge-only)
2. Hold BOOT button while plugging in USB
3. Use ESPWEBTOOL as an alternative web flasher
4. As last resort, use esptool.py CLI: esptool.py --chip esp32s2 write_flash 0x0 firmware.bin

Download prebuilt binary

USB-C is for flashing only

The USB-C port provides power to the ESP32-S2 microcontroller only. It cannot power the fans. Fans require an external 12V DC power supply connected to the DC input jack (5.5x2.1mm).

ESP32-S2 Pin Assignment

Pin	Usage
GPIO0	Boot Button, Push to enter flashing mode
GPIO1	Status LED (PWM-controlled, monochromatic with pulse effects)
GPIO2	Expansion Header (Bottom)
GPIO3	Expansion Header (Bottom)
GPIO4	Expansion Header (Bottom)
GPIO5	Expansion Header (Bottom)
GPIO6	Expansion Header (Bottom)
GPIO7	Expansion Header (Bottom)
GPIO8	Expansion Header (Bottom)
GPIO9	Expansion Header (Bottom)
GPIO10	Expansion Header (Bottom)
GPIO11	Expansion Header (Bottom)
GPIO12	Fan 1 PWM
GPIO13	Fan 2 PWM
GPIO14	Fan 3 PWM
GPIO15	Fan 4 PWM
GPIO16	Fan 1 Speed Sense
GPIO17	Fan 2 Speed Sense
GPIO18	Fan 3 Speed Sense
GPIO21	Fan 4 Speed Sense
GPIO26	unused
GPIO33	I2C SDA
GPIO34	I2C SCL
GPIO35	I2C INT
GPIO36	USR3
GPIO37	USR2
GPIO38	USR1
GPIO42	Neopixel Expansion Port
GPIO45	unused (strapping)
GPIO46	unused (strapping)

I2C Extension Port

The board offers an I2C extension port above Fan 4.

Nr.	Pin	Description
1	GND
2	INT	GPIO 35
3	SCL	GPIO 34, 4.7k Pull-Up
4	SDA	GPIO 33, 4.7k Pull-Up
5	+3V3

SMD Expansion Port

The board offers an SMD expansion port on the back.

Nr.	Pin	Description
1	+3V3
2	+5V
3	I/O	GPIO02
4	I/O	GPIO03
5	I/O	GPIO04
6	I/O	GPIO05
7	I/O	GPIO06
8	I/O	GPIO07
9	I/O	GPIO08
10	I/O	GPIO09
11	I/O	GPIO10
12	I/O	GPIO11
13	GND
14	GND

Example Configurations

• Basic Configuration — Minimal setup with 4 fans and essential features

For more examples, see the examples directory.