This directory contains libraries specifically targeting the RP2040 or possible future related devices. It is selected when PICO_PLATFORM=rp2040
(the default) is specified for the build
hardware_
libraries exist for individual hardware components to provide a simple API providing a thin abstraction hiding the details of accessing the hardware registers directly.
pico_
provides higher level functionality you might generally find in say an OS kernel, as well as runtime support familiar to most C programmers.