crazyflie-firmware-src/src/deck/interface/deck.h

-// Includes all the deck C API headers
-
-#ifndef __DECK_H__
-#define __DECK_H__
-
-/* Core: handles initialisation, discovery and drivers */
-#include "deck_core.h"
-
-/* Deck APIs */
-#include "deck_constants.h"
-#include "deck_digital.h"
-#include "deck_analog.h"
-#include "deck_spi.h"
-
-#endif

crazyflie-firmware-src/src/deck/readme

-Deck API
-========
-
-This folder contains files implementing the deck I/O API. Currently only the
-Crazyflie 2.0 implements this api for the Deck expantion port I/Os.
-
-The API is inspired by the Arduino API. It implements the arduino API mapping
-C++ to C function in a consistent way.