Editing General-purpose input/output (section)

==Integrated circuit GPIOs==
Integrated circuit (IC) GPIOs are implemented in a variety of ways. Some ICs provide GPIOs as a primary function whereas others include GPIOs as a convenient "accessory" to some other primary function. Examples of the former include the [[Intel 8255]], which interfaces 24 GPIOs to a [[parallel communication]] bus, and various GPIO ''expander'' ICs, which interface GPIOs to [[serial communication]] buses such as [[I²C]] and [[SMBus]]. An example of the latter is the [[Realtek]] ALC260 IC, which provides eight GPIOs along with its main function of [[audio codec]].

[[Microcontroller]] ICs usually include GPIOs. Depending on the application, a microcontroller's GPIOs may comprise its primary interface to external circuitry or they may be just one type of I/O used among several, such as [[analog signal]] I/O, counter/timer, and serial communication.

In some ICs, particularly microcontrollers, a GPIO pin may be capable of other functions than GPIO. Often in such cases it is necessary to configure the pin to operate as a GPIO (vis-à-vis its other functions) in addition to configuring the GPIO's behavior. Some microcontroller devices (e.g., Microchip dsPIC33 family) incorporate internal signal routing circuitry that allows GPIOs to be programmatically mapped to device pins. [[Field-programmable gate array]]s (FPGA) extend this ability by allowing GPIO pin mapping, instantiation and architecture to be programmatically controlled.

Some microcontrollers and FPGAs allow a device to offload the task of bit-banging the GPIO to a separate device, the [[programmable input/output]] controller.

<gallery>
File:Ic-photo-Intel--D8255.JPG|Parallel bus interface to 24 GPIOs ([[Intel 8255]])
File:Rockwell R6522P Versatile Interface Adapter.jpg|A "versatile interface adapter", which combines 20 GPIOs with other general-purpose interfaces ([[MOS Technology 6522]])
File:PIC18F8720.jpg|A [[PIC microcontrollers|PIC microcontroller]] with 29 remappable GPIOs ([[Microchip Technology]] PIC24FJ256)
</gallery>