AS3935 lightning detector
Also known as: AS3935 · CJMCU-3935 · DFRobot SEN0290 · Garden & weather
A storm early-warning system on a breadboard: strikes register minutes before the rain, which is exactly enough time to close awnings and pull the drone inside.
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At a glance
⚑ flag an error| Measures | lightning |
|---|---|
| Accuracy | Detects strikes to ~40 km with rough distance estimate |
| Interface | I2C @ 0x03 (varies) (SPI supported too) |
| Supply | 3.3–5 V |
| Battery-viable | Yes (deep-sleep friendly) |
| ESPHome | Native ESPHome component — as3935_i2c |
| Typical price | $5-9 (street, varies) |
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Clone check
HIGH clone risk. CJMCU clone boards ship wrong antenna tuning caps and fail calibration outright. If you want it to actually work, buy the DFRobot SEN0290 or SparkFun board. How to check what you received →
Good for
Gotchas to know
- Indoor electrical noise (LED PSUs, motors) causes endless 'disturber' false alarms — tune spike rejection and placement patiently.
- Antenna must be calibrated to 500 kHz; genuine boards do this properly, clones often can't.
- $5 buys the clone lottery; ~$25 buys the DFRobot one that works.
Wiring it up
It's I2C, so it shares two pins with every other I2C sensor you own — chain your climate/light/CO2 stack on one bus and mind the address clashes (this one lives at 0x03 (varies)). Any ESP32 dev board works.