In this article we are discussing Embedded Interface – PCF8574 and PCF8574A I/O Expender.
The PCF8574 device provides general-purpose remote I/O expansion for most micro controllers
families by way of the I2C interface [serial clock(SCL), serial data (SDA)]. 8-bit 2.5- to 5.5-V I2C/SMBus I/O expander with interrupt
The device features an 8-bit quasi-bidirectional I/O port (P0–P7), including latched outputs with high current drive capability for directly driving LEDs. Each quasi-bidirectional I/O can be used as an input or output without the use of a data-direction control signal. At power on, the I/Os are high. In this mode,
only a current source to VCC is active.