This zip file contains everything necessary to adapt the Arduino libraries to the target board or chip.

In Sept. 2013, [Squonk42] posted up on the Arduino forums requesting the schematics and editable design files for the Arduino Yun, and he still hasn’t received them or even a response.

So just like with open source software, people can and do make derivatives of Arduino boards or entirely new products powered by Arduino technology. Why is openness important in hardware?

Arduino: this hardware/software combo allows you to program chips and test them on the fly—a real advantage of open hardware. One of the wacky creations possible with Arduino, this spider-like robot ...

If you want to develop a program on Arduino with Raspberry Pi, then this tutorial has all the steps you need to take for it, in detail.

Thanks to the open-source community aspects of Arduino, makers and developers are sharing their code, libraries, and drivers for all to use.