What happens if a sketch uses code like
pinMode(18,INPUT_PULLDOWN) to configure internal pull-down (or pull-up) resistors, but is used in a circuit where external resistors are also present?
Are there likely to be any problems, conflicts or unexpected behaviour, e.g. if software sets a pull-down, but there is an external pull-up, or visa versa?
I am using an ESP32 (which has both internal pull-ups and pull-downs available on most GPIO pins), but I would appreciate a general answer. To clarify, I am not after the pros and cons of using external resistors (which is discussed in other questions), but the potential pitfalls of using both, especially if they are pulling in opposite directions.