The GPIO pins


All microcontrollers have GPIO pins
GPIO means "General Purpose Input/Output"
Some manufacturers call them just PIO or Parallel I/O
Sometimes their are called I/O pins
....

They are usually divided in groups, called "ports"
Ports are of varying width
AVR has 8-bit ports (it's an 8-bit CPU)
Some Cortex-M implementations offer 12-bit ports
Most have 16-bit or 32-bit ports
Not all bits can be instantiated
Sometimes ports may have as few as 0 useful bits
Fortunately, vendors use proper "sparse" names

If you use the concept of ports, they *must* be 32b wide
We have so many numbers in one integer
Portability is paramount