This is a timed password-guessing challenge rather than an actual security lock — a race against a 10-second countdown to enter the right three-digit code using nothing but an IR remote.
Components needed
An Arduino Uno, a 7-segment display, a 16x2 I2C LCD, an IR receiver and remote, a red LED and a yellow LED, and a breadboard.
Wiring it up
The 7-segment display's A–G pins connect to digital pins 2 through 8, the LCD uses standard I2C wiring on A4/A5, the two LEDs connect to pins 9 and 10, and the IR receiver connects to pin 11.
How the game works
Once started, the 7-segment display begins counting down from 10 while the LCD shows game status messages. The player enters a three-digit sequence using the remote's number buttons before time runs out — the correct sequence in this build is "112." Each correct digit advances the game forward; the game resets and starts over if the countdown reaches zero before the sequence is complete.
Success and failure feedback
Getting the full sequence right in time lights the green success LED and shows a success message on the LCD; running out of time or entering a wrong digit lights the red LED and displays a "try again" message instead, resetting the game for another attempt.
How this differs from our other lock and safe projects
Unlike our keypad door-lock or the two-input safe project, this one doesn't actually control any lock or mechanism — there's no servo, no bolt, nothing physically secured. It's built purely as a reflex-and-memory challenge game using the same kind of "enter a code" interaction, worth building specifically for the countdown-timer and pass/fail feedback mechanics rather than as a real access-control system.
You can find 7-segment displays and IR receiver modules at Juthour Tech.
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