Automatic Curtain Opener with Light Sensor

Curtains left closed all day waste free daylight, and remembering to open and close them on schedule is the kind of chore automation exists for. A light sensor knows dawn and dusk better than any clock, and a stepper motor can position curtains precisely — the engineering work is in the light threshold with hysteresis, the belt drive mechanics and the manual override. This project builds a student-scale automatic curtain opener on an ESP32: an LDR module tracks ambient light, and when it crosses the configured day/night thresholds the stepper motor drives the curtain carrier along the rail via a belt and pulley. The LCD shows light level and curtain state, and manual buttons open or close the curtains regardless of the sensor.

1. The LDR module continuously reports ambient light level to the ESP32, shown live on the LCD.
2. When the reading rises above the day threshold, the ESP32 drives the stepper motor through its driver, and the belt pulls the curtain carrier to the open end of the rail.
3. When the reading falls below the night threshold, the motor runs in reverse and the curtains close.
4. Hysteresis between the two thresholds means a passing cloud cannot trigger repeated open-close cycles.
5. Pressing the manual open or close button moves the curtains immediately and suspends automatic moves until the next threshold crossing.
6. The firmware ramps stepper speed at the start and end of each move for smooth, quiet motion.

Tech stack:

• ESP32 development board
• LDR light sensor module
• Stepper motor with driver (ULN2003/A4988 class)
• Belt and pulley rail drive
• 16x2 character LCD
• Push buttons
• Arduino IDE (C/C++ firmware)

• [Daylight-responsive operation] An LDR light sensor opens the curtains when ambient light rises past the day threshold and closes them when it falls past the night threshold.
• [Stepper motor belt drive] A stepper motor with pulley and belt moves the curtain carrier along the rail with repeatable positioning.
• [Hysteresis thresholds] Separate day and night trip points stop the curtains from hunting back and forth in marginal light like cloudy afternoons.
• [LCD status display] A 16x2 LCD shows the live light reading plus OPEN, CLOSED and MOVING states.
• [Manual override buttons] Open and close buttons take immediate control and hold the manual position until the next threshold crossing.
• [Adjustable sensitivity] A potentiometer trims the light thresholds, so dawn/dusk behaviour can be tuned and demonstrated.
• [Smooth motion control] Firmware ramps the stepper speed up and down so the curtains glide instead of jerking.

• Working model window with curtain rail, belt drive, stepper motor, ESP32, LDR sensor and LCD
• Complete firmware with commented light-threshold and stepper-control logic
• Wiring diagram and connection table
• Threshold and hysteresis tuning procedure
• Project report PDF (background, system design, firmware logic, test observations)
• PPT presentation for final review
• Viva Q&A preparation document (LDR sensing, stepper motors, hysteresis, ESP32)

• The prototype uses a lightweight model curtain and rail — real curtains need a stronger motor and a full mechanical redesign.
• LDR readings depend on sensor placement and room lighting; thresholds are tuned by the buyer with the included procedure.
• The system reacts to ambient light only — it has no clock, so scheduled times are listed as future scope (RTC addition).
• Travel time and positioning repeatability are design targets verified on the buyer's own build, not certified figures.
• Heavy or blackout curtains exceed the demo motor's torque; the demo uses light fabric.
• No Wi-Fi remote control is included — operation is fully on-device.