The lap timer tracks your Mini 4WD car's lap times in real time using an IR sensor connected to an Arduino. Open http://localhost:8080 in your browser to access the timer.
Shows the time elapsed for the lap currently in progress. Resets to 0:00.0 at the start of each new lap.
Shows the total time elapsed for the entire race session, excluding any paused time.
| Field | Location | Description |
|---|---|---|
| Total Time | Top left | Sum of all completed laps |
| Lap | Top right | Number of completed laps |
| Last Lap | Bottom left | Time of the most recently completed lap |
| Best Lap | Bottom right | Fastest lap of the session — highlighted in gold |
A scrolling list of every completed lap. The best lap is marked with a ★.
Appears when the timer is idle. Arms the sensor and waits for the car to cross the IR beam for the first time. A 3-beep countdown plays to signal the timer is ready.
Ends the race session immediately. The session is saved to history. A descending sound plays to confirm.
Freezes both the current lap and race timers. The car's position is noted — use this when you need to interrupt a run.
Appears after pausing. Clicking Resume puts the timer into a waiting state — the timers do not start immediately. Place the car at the track and let it pass the IR sensor; the moment it crosses, the race timer resumes and a fresh lap begins. A GO sound plays on the trigger.
Appears when paused. Removes the current incomplete lap from the race timer without ending the session. Useful when you want to discard a partial lap before resuming.
Clears all lap data and returns the timer to idle. The session is saved to history before resetting. A descending arpeggio plays to confirm.
Sounds can be toggled on or off in the Settings panel at the bottom of the page. The preference is saved between sessions.
| Event | Sound |
|---|---|
| Start armed | 3 short beeps (countdown) |
| Car crosses start line | Rising two-note GO burst |
| Lap completed | Bell ping |
| New best lap | Ascending arpeggio (C–E–G–C) |
| Pause | Descending two-tone |
| Resume clicked | Rising two-tone |
| Stop | Low descending blip |
| Reset Time | Soft tick |
| Reset | Descending arpeggio |
- Click Start — 3 beeps confirm the sensor is armed
- Release the car — the timer starts the moment it crosses the IR beam
- Each time the car completes a lap, the lap time is recorded automatically
- Click Stop when the race is over — the session is saved
- Click Reset to clear and start fresh for the next race
- Click Pause — both timers freeze
- Optionally click Reset Time to discard the current partial lap
- Click Resume — the timer waits in a ready state
- Send the car through the IR beam — race resumes with a fresh lap
Past sessions are stored and accessible via the Session History panel at the bottom of the page. Click the panel header to expand it, then click any session to see its individual lap times.
The indicator in the top-right corner shows the live connection to the sensor:
- Green dot — connected, sensor active
- Red dot — disconnected, attempting to reconnect automatically