Editing General-purpose input/output (section)

==Board-level GPIOs==
Many circuit boards expose board-level GPIOs to external circuitry through integrated electrical connectors. Usually, each such GPIO is accessible via a dedicated connector pin.

Like IC-based GPIOs, some boards merely include GPIOs as a convenient, auxiliary resource that augments the board's primary function, whereas in other boards the GPIOs are the central, primary function of the board. Some boards, which are classified usually as multi-function I/O boards, are a combination of both; such boards provide GPIOs along with other types of general-purpose I/O. GPIOs are also found on embedded controller boards and [[Single board computer]]s such as [[Arduino]], [[BeagleBone]], and [[Raspberry Pi]].<ref>{{Cite web |url=https://www.raspberrypi.org/documentation/hardware/raspberrypi/gpio/README.md |title=GPIO – Raspberry Pi Documentation |website=Raspberry Pi Foundation |access-date=2016-11-03}}</ref>

While some board-level GPIOs are simple connection to IC pins, many are given abilities which IC-based GPIOs usually lack. For example, [[Schmitt-trigger]] inputs, high-current output drivers, [[optical isolator]]s, or combinations of these, may be used to buffer and condition the GPIO signals and to protect board circuitry. Also, higher-level functions are sometimes implemented, such as input [[debounce]], input [[signal edge]] detection, and [[pulse-width modulation]] (PWM) output.

<gallery>
BPI-R1-GPIO.jpg|Network router with three GPIOs (Banana Pi R1)
HP 82940A GPIO Interface interior.jpg|GPIO interface for Hewlett-Packard Series 80 computers (HP 82940A)
48 GPIO Ethernet interface.jpg|Ethernet interface to 48 GPIOs (Sensoray 2410)
Asus Tinker Board.jpg|Color coded GPIOs (top) on an [[Asus Tinker Board]]
</gallery>