GPIO pin doesn't have output

[LFu.1]

I configure 6 channel GPIO pins to generate PWM signals to control 3-phase bridge. There is one pin(PC13) sometimes stop to generate signal. Even we reset 3.3V power voltage, it won't recover. one time I inject 20k square wave to pin PC13 to verify other chip， but it cause the processor recovered. I use pin PA7 to sampling voltage(use as internal op-amp ）, it always has 1V even turn off 3.3V power. I am guessing because of this voltage cause the processor can't reset completely? How to explain these？

Thanks，​

[TDK]

Sounds like there may be hardware issues going on. Pulling NRST low will reset the processor under normal scenarios.

If pins have a voltage on them while VDD is 0V, something external must be driving them high.

PC13 is special as it runs off of the low-power domain and has limited source/sink capability.

[LFu.1]

Thanks for your answer. How can we explain the processor can't get Reset properly. I guess it is because of PA7 has 1V voltage. But I am not sure. The issue didn't come up frequently. It is very hard to verify.