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ESP32 & ESP8266
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Topic starter
2026-04-26 6:27 pm
Hello Forum,
I’m building a signal monitor using a XIAO ESP32-C3 microcontroller. The design includes:
- One input protected with an optocoupler
- One output driving an NPN transistor to turn on an LED
- A Hi-Link HLK-PM01 5V power supply
When I power up the PCB, the XIAO output pin gets damaged. I have carefully measured voltages and resistances without the XIAO installed, and everything appears to be normal.
So far, I have already damaged 4 microcontrollers during different tests.
Does anyone have any idea what could be causing this issue?
this is the diagram
thanks
huerta69
2026-04-27 4:47 am
- XIAO ESP32-C3
- Operating Voltage: 3.3V.
2026-04-27 11:15 am
@biakss Yes, it is a 3.3-volt microcontroller, but, like all XIAO boards, it can be powered by a 5-volt input. So the diagram is correct.
@huerta69 Can you test this with the output transistor disconnected? Replace the output with a logic probe, scope, or even a voltmeter. Frying the microcontroller indicates you're drawing too much current.
Another thought is on the power side. Did you perhaps have the XIAO connected to your computer when powering this up? That would cause issues as the 5-volt input becomes a 5-volt output, and you would be connecting two power supplies together, which usually results in bad things happening! The solution here is a diode in series with the external 5-volt supply.
😎
Bill
"Never trust a computer you can’t throw out a window." — Steve Wozniak