Objective:
Build a smart stopwatch displayed on a 4-digit 7-segment display (5641AS) and controlled by a motion sensor (HC-SR501).
The timer starts on its own, pauses when motion is detected, and resumes only if a second motion is detected at least 20 seconds later.
Components used:
- 1x Arduino Uno
- 1x 5641AS 4-digit display (common cathode)
- 1x HC-SR501 PIR motion sensor
- 4x 220Ω resistors (one per segment)
- Jumper wires, breadboard
- (Optional) Tweezer/screwdriver for adjusting the PIR
How it works:
- The timer starts automatically at 0.
- When motion is detected, the timer pauses.
- A second motion, if detected after at least 20 seconds, will resume the timer.
- If the second motion is too soon, it will be ignored.
The display shows minutes : seconds : tenths of seconds.
For example, 1234 : 12 minutes and 34 seconds.
Result:
- A clean and readable live time display.
- A motion-based pause/resume system.
- A great hands-on practice with state logic and time-based decision-making on Arduino.
Code and setup:
- It uses the SevSeg library to easily control the display.
- Code logic handles debouncing, timing, and PIR behavior cleanly.
- Download project file (PIRMotionSensor.ino)
To ensure fast and proper motion detection:
- Turn the “Time Delay” right potentiometer fully counterclockwise on the PIR sensor.
You can also check my LED control project with a joystick and servo for another use of sensors and feedback.
Laisser un commentaire