i have STM32F103C8T6 suddenly the pins of the MCU is not working. Are the pins fried ? The 3.3v or 5v pins does not work when I connect a LED using 1k res. But when i try to run the Blinky app in eclipse and choose the internal LED PC13 to blink it works

[TDK]

If you can connect to the chip, it's probably fine, especially as PC13 works. Verify LED polarity. What pin are you trying to use? Verify the hardware connection is there.

Always a possibility that a pin is damaged, but they don't damage themselves. Had to be an event that caused it.

[Javier1]

What if the LED yure trying to connect is broken or with the wrong polarity?

[HAli.2]

Well, I have already made sure of that. I connected an external 3.3v and it works well

[HAli.2]

The LED is working well and i already made sure of that. But with alot of testing i figured out that the problem is in the GND pins of the MCU somehow.

[HAli.2]

I used the GND of the st link programmer and tried all of GPIO pins and it worked.

For some reason the GND of the MCU is not working.

[Javier1]

if your internal PC13 (green if youre using a bluepill) is working and your external LED is not , there is a hardware/wiring problem.

Could you show us your setup?(pìctures)