Smart Fan (Raspberry Pi Pico 2 W)

Firmware for a smart fan powered by Raspberry Pi Pico 2 W, controllable via a physical rotary switch, a Web interface, and Modbus TCP.

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📌 Pinout & Hardware Wiring

1. Rotary Switch (Inputs)

Configured as digital inputs with internal pull-ups. Connect the common pin of the switch to GND (Active LOW).

Pico 2 W Pin	GPIO	Component Pin	Notes
Pin 2	GP1	Rotary Switch Position 1	Pulled LOW when Position 1 selected
Pin 4	GP2	Rotary Switch Position 2	Pulled LOW when Position 2 selected
Pin 5	GP3	Rotary Switch Position 3	Pulled LOW when Position 3 selected
GND	GND	Rotary Switch Common Pin	Ground connection

2. Fan Speed Control Outputs (Relays / Triacs)

Configured as digital outputs with Active LOW logic (HIGH = OFF, LOW = ON).

Pico 2 W Pin	GPIO	Control Line	Logic
Pin 15	GP11	Speed 1 Relay / Driver	0 = ON, 1 = OFF
Pin 16	GP12	Speed 2 Relay / Driver	0 = ON, 1 = OFF
Pin 17	GP13	Speed 3 Relay / Driver	0 = ON, 1 = OFF

3. Status LED

• Onboard LED (CYW43_WL_GPIO_LED_PIN):
  • Solid ON: Wi-Fi connected.
  • OFF: Wi-Fi disconnected / reconnecting.

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🛠 Build & Flash

Prerequisites

• CMake (>= 3.13)
• GCC ARM Toolchain (arm-none-eabi-gcc)
• Pico SDK (with PICO_SDK_PATH environment variable set)

Building

mkdir build && cd build
cmake -DWIFI_SSID="Your_SSID" -DWIFI_PASSWORD="Your_Password" ..
make -j4

Copy the generated smart_fan.uf2 to your Raspberry Pi Pico 2 W in BOOTSEL mode.

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📡 Modbus TCP Documentation

The device acts as a Modbus TCP server listening on port 502.

Address	Register Type	Access	Description	Values
100	Holding Register (0x03, 0x06, 0x10)	Read / Write	Fan Speed	0: Off 1: Speed 1 2: Speed 2 3: Speed 3
100	Input Register (0x04)	Read-only	Last Change Source	0: None 1: Rotary switch 2: Web interface 3: Modbus