Rev 3.x (3.1 / 3.2 / 3.3)

The Rev 3.x series is the latest generation of the WiFi Fan Controller. All 3.1, 3.2, and 3.3 boards share identical firmware and pinout — differences between sub-revisions are hardware-only improvements.

Key features over Rev 3.0: RGB status LEDs (SK6805) for board status and per-fan visual feedback.

Hardware Package Import

Add this to your ESPHome config to import the hardware package for your board revision:

Rev 3.3

packages:
  hardware:
    url: https://github.com/zeroflow/wifi-fancontroller
    ref: main
    files: [hardware-rev-3.3.yaml]

Rev 3.2

packages:
  hardware:
    url: https://github.com/zeroflow/wifi-fancontroller
    ref: main
    files: [hardware-rev-3.2.yaml]

Rev 3.1

packages:
  hardware:
    url: https://github.com/zeroflow/wifi-fancontroller
    ref: main
    files: [hardware-rev-3.1.yaml]

Board Photos

Rev 3.3

Rev 3.2

Rev 3.1

Specifications

• MCU: ESP32S2-Mini-2
• Board platform: esp32-s2-saola-1
• Power: DC Input (12V, 5.5x2.1mm)
• Max total input current: 2.5A (set by the DC barrel jack — applies to the sum of all fans plus board electronics, not per fan header; size your 12V PSU accordingly)
• Flashing: USB-C port
• Fan outputs: 4x PWM headers with signal buffering
• Status LEDs: SK6805 RGB LEDs for board status and each fan connector
• 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 on GPIO42 requires the arduino framework. The esp32_rmt_led_strip platform used for this pin does not work reliably with esp-idf on the ESP32-S2.

Factory Firmware Installation

Select your board revision and click the button to flash the factory firmware directly from your browser via USB.

Rev 3.3

Flash Rev 3.3 Factory Firmware

Rev 3.2

Flash Rev 3.2 Factory Firmware

Rev 3.1

Flash Rev 3.1 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 (flash binary at address 0x0)
4. As last resort, use esptool.py CLI: esptool.py --chip esp32s2 write_flash 0x0 firmware.bin

Download prebuilt binaries: Rev 3.1 / Rev 3.2 / Rev 3.3

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

This pin table applies to all Rev 3.1, 3.2, and 3.3 boards.

Pin	Usage
GPIO0	Boot Button, Push to enter flashing mode
GPIO1	RGB Status LEDs, SK6805 (5 LEDs, ESPHome uses WS2812 driver, GRB color order)
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
GPIO43	UART0 TX (U0TXD), Serial Flashing Header
GPIO44	UART0 RX (U0RXD), Serial Flashing Header
GPIO45	unused (strapping)
GPIO46	unused (strapping)

Serial Flashing Header (TX/RX)

In addition to the USB-C port, the board exposes the ESP32-S2 UART0 on a serial header for flashing and serial logs. This is the fallback path when USB-C is not detected (see the USB troubleshooting note above) and the channel ESPHome’s logger uses by default.

Signal	Pin	Description
3.3V	3.3V
TX	GPIO43	UART0 transmit (U0TXD), board to host
RX	GPIO44	UART0 receive (U0RXD), host to board
GND	GND	Common ground (required for serial)

Connect a 3.3V USB-to-serial adapter (TX to RX, RX to TX, GND to GND). To enter the bootloader for flashing, hold BOOT (GPIO0) while resetting the board.

3.3V logic only

The ESP32-S2 UART pins are 3.3V. Do not connect a 5V serial adapter directly to TX/RX.

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

Qwiic Connector

The board offers a Qwiic connector (standard JST-SH 4-pin, 1mm pitch) for solderless I2C expansion. It shares the same I2C bus as the 100mil I2C extension port and the onboard HDC1080 sensor, so addresses must not conflict across both ports.

Nr.	Pin	Description
1	GND	Black wire
2	+3V3	Red wire
3	SDA	GPIO 33, blue wire, 4.7k Pull-Up
4	SCL	GPIO 34, yellow wire, 4.7k Pull-Up

Shared I2C bus

The Qwiic port, the 100mil I2C extension port, and the onboard HDC1080 temperature/humidity sensor are all on the same I2C bus (GPIO33 SDA / GPIO34 SCL). Devices on any of these connectors share that bus.

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 Setup

• Rev 3.3 Basic — Minimal setup with 4 fans
• Rev 3.2 Basic — Minimal setup with 4 fans
• Rev 3.1 Basic — Minimal setup with 4 fans

Advanced Features

• RGB Status LEDs — Visual fan speed feedback with color-coded LEDs (red=slow, green=fast)
• RPM PI Control — Closed-loop RPM regulation per fan
• Temperature Control (Linear/PID) — Automatic fan speed adjustment based on temperature
• Temperature Curve — Flexible 5-point temperature curve with linear interpolation

For all available examples, see the examples directory.

Revision History

All Rev 3.1, 3.2, and 3.3 boards share identical firmware and pinout. The differences between sub-revisions are hardware-only improvements:

Revision	Changes
Rev 3.1	Added RGB status LEDs (SK6805) for board + per-fan indication
Rev 3.2	Improved USB-C fuse for better overcurrent protection
Rev 3.3	Open-drain fan outputs, optimized component selection, enhanced power supply stability