This project implements a fan controller for a water-cooled computer system using a Seeed Studio Xiao ESP32C3 microcontroller. It controls 4 PWM fans (including a water pump) based on temperature readings from 3 thermistors, aiming to balance cooling performance with noise levels.

• Intelligent Fan Control:
  • Controls 4 PWM fans (25kHz frequency).
  • Fan speed is calculated using a hybrid formula considering both the temperature delta (Ambient vs. Coolant) and absolute water temperature.
  • Smooth fan speed transitions to prevent rapid RPM fluctuations.
  • Configurable minimum speeds (Pump: 50%, Fans: 35%).
• Temperature Monitoring:
  • Supports 3 thermistor probes (Ambient, Coolant In, Coolant Out).
  • Automatic calibration for 10k and 50k thermistors.
  • Validation logic to detect and handle sensor errors.
• RPM Monitoring:
  • Reads fan RPM using tachometer signals.
  • Uses a circular buffer and polling for noise filtering on tachometer inputs.
• Web Interface:
  • Built-in HTTP server (Port 80).
  • Displays real-time status of fans (Duty Cycle, RPM) and temperatures.
  • Allows manual override of fan duty cycles.
  • Displays system logs.
• Performance Logging:
  • Logs system state (Fan PWM, RPM, Temperatures) every second to internal flash storage.
  • Rotates log files automatically.
  • Provides a separate HTTP file server (Port 5599) to download performance logs.
• Connectivity:
  • WiFi enabled.
  • Over-the-Air (OTA) updates (via PlatformIO).

• Microcontroller: Seeed Studio Xiao ESP32C3
• Inputs:
  • 3x Thermistors (NTC 10k or 50k) on Analog pins (A0, A1, A2).
  • 4x Fan Tachometer signals.
• Outputs:
  • 4x PWM Fan control signals (D3 - D10 pairs).

• Framework: PlatformIO with Arduino framework for ESP32.
• OS: FreeRTOS is used for task management (Main loop, Fan control, Logging).
• Language: C++ (following Google C++ Style Guide).
• Error Handling: Uses a custom Status and StatusOr implementation for robust error handling.

• src/main.cpp: Main entry point, setup, and loop.
• lib/AppModules/: Application logic libraries.
• lib/Sensors/: Reusable sensor libraries (Fan, Thermistor).
  • fan_controller: Logic for calculating fan speeds based on temperature.
  • pwm_fan: Handles PWM output and tachometer reading.
  • thermistor: Handles temperature reading and calibration.
  • http_server: Web interface implementation.
  • perf_logger: Binary logging of system performance.
  • logger: Serial logging utility.
• tools/: Utility scripts (e.g., for parsing binary logs).

1. Prerequisites: Install Visual Studio Code and the PlatformIO extension.
2. Configuration:
   • Rename include/secrets.h.example to include/secrets.h.
   • Update secrets.h with your WiFi credentials.
3. Build & Upload:
   • Connect the Xiao ESP32C3 via USB.
   • Use PlatformIO to build and upload the firmware.
4. Monitor:
   • Use the Serial Monitor to view initial connection logs and IP address.
   • Access the web interface via the assigned IP address.

This project supports OTA updates, allowing you to flash new firmware wirelessly.

1. Initial Setup: Flash the firmware via USB once to enable OTA.
2. Find IP Address: Note the IP address of the device (printed to Serial Monitor or found on your router).
3. Update platformio.ini: Uncomment or add the following lines to your platformio.ini environment:

   ; upload_protocol = espota
   ; upload_port = YOUR_DEVICE_IP_ADDRESS

4. Flash: Run the "Upload" task in PlatformIO. It will now upload via WiFi.