⚡ Lightning Detector

AS3935 Franklin Lightning Sensor + TTGO Wemos ESP32 OLED

A lightning detector based on the AS3935 sensor (WCMCU-3935 module) and ESP32 microcontroller with built-in OLED display. Detects lightning activity, estimates distance to storm front, and displays real-time data on a 128x64 OLED screen.

---

📋 Features

• ⚡ Lightning detection up to 40 km radius
• 📏 Distance estimation in 15 steps (1–40 km)
• 🔋 Ultra-low sensor power consumption (~80 µA in listening mode)
• 🖥️ Real-time OLED display with adaptive info line
• 📊 Distinguishes between Lightning, Disturber, and Noise
• 🔢 Disturber counter per session
• 📶 Noise level indicator (0–7 scale)
• ⏱️ Auto-reset to Quiet: 10 sec after lightning, 5 sec after disturber
• 🔇 Optional WiFi/BT disable to reduce EMI interference
• 🔌 No external AS3935 library — direct register access via Wire

---

🛒 Hardware

Component	Details
Microcontroller	TTGO Wemos ESP32 OLED (ESP-WROOM-32)
Lightning Sensor	WCMCU-3935 (AS3935, analog to CJMCU-3935)
Display	Built-in OLED 0.96" 128x64, SSD1306, I2C
Power	5V USB or 3.7V LiPo

---

📌 Pinout Diagram

🔌 Wiring

Only 5 wires from ESP32 to sensor:

Wire	ESP32	WCMCU-3935	Color
Power	3.3V	VCC + SI + A0 + A1 + EN_V	Red
Ground	GND	GND + CS	Black
I2C Data	GPIO5	MOSI	Blue
I2C Clock	GPIO4	SCL	Green
Interrupt	GPIO13	IRQ	Yellow

⚠️ Important: Tie SI, A0, A1, EN_V together to 3.3V. Tie CS together with GND.

Pin Notes for TTGO Wemos ESP32 OLED

Signal	GPIO	Note
OLED SDA	GPIO5	Reversed from ESP32 standard!
OLED SCL	GPIO4	Reversed from ESP32 standard!
OLED RST	GPIO16	Required — OLED won't start without it
AS3935 IRQ	GPIO13	Interrupt input

I2C Addresses

Device	Address
OLED SSD1306	0x3C
AS3935	0x03 (A0=1, A1=1)

---

🖥️ OLED Display Layout

┌──────────────────────────┐
│   Lightning Detector     │  ← header
├──────────────────────────┤
│ Dist:  27 km             │  ← distance (size 2)
├──────────────────────────┤
│ Energy:   48321          │  ← adaptive info line
│ Status: Lightning!       │  ← status
└──────────────────────────┘

Adaptive Info Line

Status	Info Line Shows
Quiet	Energy: 0
Lightning!	Energy: 48321
Noise!	Noise lvl: 4/7
Disturber	Disturb: 7x

---

📦 Libraries Required

Install via Arduino IDE Library Manager:

• Adafruit SSD1306 — OLED display driver
• Adafruit GFX Library — installed automatically with SSD1306

AS3935 uses direct Wire register access — no external library needed.

---

⚙️ Arduino IDE Setup

1. Add ESP32 board URL in File → Preferences:

   https://dl.espressif.com/dl/package_esp32_index.json
   

2. Install esp32 by Espressif Systems via Board Manager

3. Select board settings:

   Parameter	Value
   Board	ESP32 Dev Module
   Upload Speed	921600
   CPU Frequency	240MHz
   Flash Mode	DIO
   Flash Size	4MB

4. If upload fails — hold BOOT, press RST, release BOOT, then upload

---

🚀 Serial Monitor Output

After upload (115200 baud):

Lightning Detector 2.4 starting...
AS3935 initialized OK
REG0x00: 0x24   // Indoor mode, active
REG0x01: 0x22   // NF_LEV=2, WDTH=2
REG0x02: 0x82   // SREJ=2, MIN_LIGH=1
REG0x08: 0x00   // DISP_SRCO=0
Ready. Waiting for lightning...

---

📡 EMI Interference Notes

The AS3935 is sensitive to electromagnetic interference. The ESP32 itself generates noise that the sensor may detect as Disturber or Noise events.

Solutions (in order of effectiveness):

1. Physically separate the sensor from ESP32 by 50–100 cm (most effective)
2. Disable WiFi/BT — uncomment in setup():

   WiFi.mode(WIFI_OFF);
   btStop();

3. Shield ESP32 in a metal enclosure
4. Use twisted pair for I2C wires

---

📁 File Structure

lightning-detector/
├── README.md
├── CHANGELOG.md
├── WIRING.md
└── lightning_detector_v24/
    └── lightning_detector_v24.ino

---

📝 Version History

Version	Changes
1.0	OLED interface with random test data
2.0	Real AS3935 sensor, direct Wire register access
2.1	Quiet timeout (10 sec)
2.2	Two separate timers: lightning (10s) and disturber (5s)
2.3	Fixed init sequence based on PWFusion library analysis
2.4	Adaptive info line, disturber counter, WiFi/BT disable option

---

📄 License

MIT License — feel free to use, modify and share.

---

🙏 References

• AS3935 Datasheet v1.04 — ams AG
• PWFusion AS3935 Library
• Embedded Adventures AS3935 Library
• RandomNerdTutorials — ESP8266 pinout reference