Blue LED flashing when Distance Sensor connected

ESPHome
1

I wanted to integrate a distance Sensor into HA using ESP Home. So I bought this ESP 32 developer board (https://www.amazon.de/dp/B0D8635YZ6?ref=ppx_yo2ov_dt_b_fed_asin_title) with this pinout

Screenshot 2025-04-05 at 13-05-46 ESP32 WROOM 32 Entwicklungsplatine Binghe 3 Stück ESP32 NodeMCU Module mit CP2102 Chip ESP-WROOM-32 2 4 GHz Dual Core WLAN WiFi Bluetooth Micro Stecker kompatibel mit Arduino Amazon.de Comput...
Screenshot 2025-04-05 at 13-05-46 ESP32 WROOM 32 Entwicklungsplatine Binghe 3 Stück ESP32 NodeMCU Module mit CP2102 Chip ESP-WROOM-32 2 4 GHz Dual Core WLAN WiFi Bluetooth Micro Stecker kompatibel mit Arduino Amazon.de Comput...679×448 255 KB

. And also this distance sensor https://www.amazon.de/dp/B072N473HD?ref=ppx_yo2ov_dt_b_fed_asin_title&th=1.

I flashed the ESP Home Firmweare to the board and everything worked perfectly fine. But as soon as I connect the 5V and GND pin of the ESP 32 to the VCC and GND pin of the sensor, the blue LED of the ESP 32 starts flashing fast.
I tried different boards and sensors. Always the same result… I also tried to connect the sensor to the VIN and GND pin of the ESP 32. Do you have any idea what might be wrong?

2

With nothing else connected to Esp pins?
How you power your Esp?

3

did you read

4

The ESP 32 is powered by USB.
I did connect the trigger pin of the sensor to pin 39 (GPIO22) and echo pin to pin 42 (GPIO21). But even without them connected the status LED of the ESP indicates an error as soon as I try to power the sensor.

5

You can’t have power coming in from both the usb and the 5v pin at the same time.

6

Of cause I did. But because the ESP indicates an error (flashing LED) as soon as I try to power the sensor, I haven’t got that far at all.

7

Ah, I can not? So when I want to power a sensor via the ESP, I need to solder a power supply to the ESP instead of plugging in an USB cable?

8

Afaik, Esp doesn’t have an error LED.
I expect short circuit causing Esp to reboot continuously.
Do you have multimeter to do some measurements?

9

The blue LED is more of a status LED, but fast flashing of the status LED indicates an error/malfunction, doesn’t it?
I have a multimeter, what measurements can I take? Are you assuming a hardware defect?

10

It would be one or the other. With a usb the amount of power that can be supplied is dependent on the type and quality of the wire. You can run into problems where the board runs fine with nothing connected but then crashes when the sensors are connected.

11

Wiring or hardware defect, measure if Esp has stable 3.3V when misbehaving.