BoardPilotResistive soil moisture sensor (YL-69 / FC-28) with ESP32
Supply 3.3-5 V
Bus ANALOG
Measures soil moisture
Pins and ESP32 wiring
| Pin | Role | ESP32 pin | Notes |
|---|---|---|---|
| VCC | Power | 3V3 | Use 3V3 so AO stays within the ADC range |
| GND | Ground | GND | |
| DO | Output (the part drives it) | D25 | Changes level at the threshold set with the trimmer |
| AO | Analog output | D34 | To an ADC pin (prefer ADC1: GPIO 32 to 39) |
Suggested wiring for the 30-pin ESP32 DevKit, avoiding flash, input-only and strapping pins. BoardPilot checks it for you as you wire.
Starter code (Arduino)
void setup() { Serial.begin(115200); }
void loop() {
int mv = analogReadMilliVolts(34); // AO on GPIO 34
Serial.println(mv);
delay(200);
}Sources
- Texas Instruments LM393 datasheet, Comparator output (DO)
- Espressif ESP32 Technical Reference Manual, ADC: input range
Try it in 3D in BoardPilot
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Part data: CC BY 4.0, free to reuse with credit to BoardPilot.