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Issue with PA2 and PA12 pin in L432KC Nucleo

xpp07
Senior

I'm using a reflective sensor to measure speed. In my PCB, I wrongly connected PA12 to the output of the sensor. I actually needed PA2 to use it as TIM2_CH3. So I jumped PA12 and PA2. This pin is pulled up to 3.3V with a 10K resistor. With no sensor connected, I clearly should read 3.3V at PA2 input, as it's pulled up. But I'm reading 1.4V. I have an external power supply for the controller. When I power up ST Link through the USB connector, then I read the 3.3V correctly. What's happening here?

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1 REPLY 1
waclawek.jan
Super User

0690X000006CHLzQAO.png

Depending on how exactly you power the target mcu, the STLink mcu might be unpowered, and then you are parasitically powering it through that solder bridge. Disconnect it.

JW