I would like to power following ultrasonic sensor using the ESP32: https://www.maxbotix.com/documents/HRXL-MaxSonar-WRS_Datasheet.pdf

Using this Heltec ESP32 board: https://heltec.org/project/wireless-stick-lite/

This board comes with an 3.3V switch denoted as Vext or Ve that is controlled by GPIO Pin 21.

Everything works quite nicely besides it throws me an error if I plug in an external sensor on the Vext pin: https://www.maxbotix.com/documents/HRXL-MaxSonar-WRS_Datasheet.pdf The external sensor is an ultrasonic sensor with a nominal current consumption of below 3mA.

Please see the error here: enter image description here

For the Vext pin, the error always occurs but strangely the error even occurs if I unplug the device during operation and plug it into the 3.3V port of the board.

This question is probably entirely related to the hardware design of the specific board but eventually you have some ideas why this Guru Meditation error can happen. Eventually due to some voltage spikes that occur while plugging the sensor in or off?

I can probably find a stable solution if I just leave the setup alone but I haven't experienced that error related to power issues.

Thank you!

  • 1
    \$\begingroup\$ There are tools to decode the backtrace line so you get more detailed information about where the code crashed. Double exception means that an exception occurred and then another one within the exception handler. \$\endgroup\$
    – Codo
    Feb 16, 2021 at 9:54

1 Answer 1


Thank you @Codo : I've installed an ESP32 Backtrace program: https://github.com/me-no-dev/EspExceptionDecoder

https://github.com/platformio/platform-espressif32/issues/105 https://github.com/me-no-dev/EspExceptionDecoder/issues https://github.com/me-no-dev/EspExceptionDecoder/issues/26

And get some more information now from the Backtrace.


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