ErickSimoes
Potential Issue: Using GPIO 34 / 35 for Ultrasonic Trigger/Echo Causes Unstable Behavior on ESP32
Hi, I'd like to share a recent issue I encountered while using this library on an ESP32 board that may help others avoid the same pitfall.
I initially set the TRIG and ECHO pins to GPIO 34 and 35 on the ESP32. After uploading the sketch, the board behaved abnormally:
It sent corrupted signals over USB, causing my mouse to move and click randomly on my PC.
The behavior persisted until I unplugged the board.
Even after resetting the board, I had to reflash it on a different PC to regain control.
Upon further testing, I changed the TRIG and ECHO pins to GPIO 17 and 25, and everything started working normally.
🔍 Diagnosis: GPIO 34 and 35 on the ESP32 are input-only pins. Using them with Ultrasonic (which needs output on the TRIG pin) seems to lead to undefined or unstable behavior. This is not a fault of the library, but it's something that may not be obvious to new users.
✅ Recommendation: Avoid using GPIO 34–39 for ultrasonic sensors, especially for the TRIG pin. Stick to GPIOs that support both input and output.
