ESP8266 WiFi Visitor Counter with OLED Display

This visitor counter uses two IR break-beam sensors positioned in a doorway (one at entry, one at exit, ~15 cm apart). By detecting which sensor is broken first, the system determines the direction of travel — counting people entering and leaving separately. The net count (in minus out) gives current occupancy. WiFi logging pushes counts to a Google Sheet every 5 minutes.

What You’ll Need

• NodeMCU ESP8266
• 2 × IR break-beam sensor pairs (emitter + receiver, 5 V)
• SSD1306 0.96″ OLED (I2C)
• Micro-USB power supply
• Cable clips and wire to mount sensors in doorway

Step-by-Step Instructions

1. Wire sensors: Each receiver output to D5 and D6 on the NodeMCU (INPUT_PULLUP mode). IR emitters powered from 3.3 V. Sensor outputs go LOW when beam is broken.
2. Wire OLED: SDA → D2, SCL → D1, VCC → 3.3 V.
3. Direction detection logic: Mount sensors A and B in doorway 20 cm apart. Use interrupts on both pins. If A triggers first then B: entry (+1). If B triggers first then A: exit (-1). Debounce with a 500 ms lockout after each transition to ignore swinging doors.
4. Display: OLED shows: “IN: XX OUT: XX” on top line, “NOW: XX people” on second line.
5. WiFi logging: Every 5 minutes, connect to WiFi and POST totals to a Google Apps Script web app (same method as the temperature logger project). The Sheet records timestamp, in count, out count, and current occupancy.
6. Mount: Use cable clips to route sensor wires neatly. Sensors face each other across the doorway at ~waist height. Secure the NodeMCU in a small project box near the door frame.

Safety Notes

• IR break-beam emitters produce invisible infrared light — not a hazard at these low power levels.
• Route wiring along wall edges, secure with clips, to prevent trip hazard.

Tips & Troubleshooting

• Direct sunlight can saturate the IR receiver — choose sensor models with modulated carrier (38 kHz) for better immunity to ambient light.
• If counts are off by one, adjust the 20 cm separation or increase the debounce time.
• For narrow doorways less than 40 cm, use a single sensor and an ultrasonic distance sensor to determine direction instead.