Pins 3.3, 3.4, which were being used for UART, have suddenly stopped working. Using them as GPIO pins is also not working. The remaining pins, functionalities appear to be working fine.
I had observed the UART not working with another board as well. I want to find out the possible reasons for this so as to take suitable precautions to avoid a recurrence of the issue. One reason for the same could be because of ESD from my body. While I don't remember touching the IC or part of the board dealing with these two pins with my bare hands there might have been inadvertent contact.
(i) Could it be a possibility that only these two pins have been affected because of ESD because they are more sensitive than the others for some reason?
The other possibility is damage because of supplying high voltages, high currents. It is extremely unlikely that this has happened here.
Are there any other causes that you could think of for such malfunctions?
Thanks and regards