An MCP expander, typically referring to devices like the MCP23017 or MCP23008, serves as an input/output (I/O) port expander. These integrated circuits provide additional GPIO (General Purpose Input/Output) pins to a microcontroller through a serial communication protocol, such as I2C or SPI. For example, a microcontroller with limited I/O pins can interface with an MCP23017 via I2C to gain 16 additional configurable digital I/O pins.
The utility of I/O expanders lies in their ability to augment the capabilities of microcontrollers in systems requiring a large number of inputs and outputs. This eliminates the need for a more complex and expensive microcontroller. They are especially useful in applications such as controlling multiple LEDs, reading numerous sensor inputs, or interfacing with keypads. Historically, the need for such devices arose from the limitations of early microcontrollers, driving the development of efficient solutions for expanding I/O capabilities without significantly increasing system complexity.
