GPIO（英语：General-purpose input/output），通用型之输入输出的简称，功能类似8051的P0—P3，其接脚可以供用户由程序控制自由使用，PIN脚依现实考量可作为通用输入（GPI）或通用输出（GPO）或通用输入与输出（GPIO），如当clk generator, chip select等。

既然一个引脚可以用于输入、输出或其他特殊功能，那么一定有寄存器用来选择这些功能。对于输入，一定可以通过读取某个寄存器来确定引脚电位的高低；对于输出，一定可以通过写入某个寄存器来让这个引脚输出高电位或者低电位；对于其他特殊功能，则有另外的寄存器来控制它们。

General-purpose input/output (GPIO) is a generic pin on an integrated circuit whose behavior—including whether it is an input or output pin—is controllable by the user at run time.

GPIO pins have no predefined purpose, and go unused by default. The idea is that sometimes a system integrator who is building a full system might need a handful of additional digital control lines—and having these available from a chip avoids having to arrange additional circuitry to provide them. For example, the Realtek ALC260 chips (audio codec) have 8 GPIO pins, which go unused by default. Some system integrators (Acer Inc. laptops) use the first GPIO (GPIO0) on the ALC260 to turn on the amplifier for the laptop's internal speakers and external headphone jack.