Weather

Weather-Resistant Camera

An STM32-based enclosure that keeps a camera lens usable in rain and frost. A vision model on the host PC (or, with the TFLite Micro path, on the MCU) detects water on the lens and triggers a servo wiper; an on-die thermistor turns a heating pad on below a threshold. UIUC ECE 445 senior design, Spring 2025.

Run it

# firmware: open Final.ioc in STM32CubeIDE, build main.c, flash the Nucleo-F4
# vision (original OpenCV heuristic):
python final_code.py               # webcam -> HSV mask -> % coverage -> "START" over serial
# vision (CNN, see CNN/README.md):
python -m lens_soiling.infer runs/procedural/soilnet.pt --camera 1 --port COM3

How it works

• Firmware (main.c). TIM2 PWM drives the servo; Set_Servo_Angle maps 0–180° to a 210–1050 tick pulse. ADC1 reads the internal temperature sensor with the factory TS_CAL1/2 calibration, and drives a MOSFET on PA5 to switch the heater. USART2 at 115200 baud accepts 5-byte commands (START, STOPP) from the PC; START sweeps the wiper 60→115→60°.
• Vision, heuristic (final_code.py). HSV threshold on low saturation and high value, morphological close, contours, enclosing circles, then percent of masked pixels. Over 5 % sends START.
• Vision, CNN (CNN/). Tile-level classifier: a ported pretrained raindrop CNN distilled into a ~20 k-parameter int8 model for TFLite Micro, plus a tested PyTorch fallback trained on synthetic drops and frost.
• Hardware. KiCad PCB (PCB Design*/), 5 V and 3.3 V regulators, MOSFET heater switch, logic-level shifter, servo header. Demo ran on the Nucleo dev board after the second PCB's MCU was damaged during hand soldering.

Layout

main.c, Final.ioc          STM32 firmware and CubeMX project
final_code.py              OpenCV heuristic + serial trigger (PC)
python_to_stm_comm.py      serial protocol smoke test
CNN/                       CNN detection: pretrained port + from-scratch pipeline
Servo Motor code/, Temperature sensor code/   subsystem test firmware
PCB Design*/               KiCad
Lab Notebooks/             per-member design logs

Stack

C (STM32 HAL), Python, OpenCV, PyTorch, TensorFlow Lite Micro, KiCad.