PCA9554PW

The PCA9554PW is a remote 8-bit I?C and SMBus I/O Expander with interrupt output and configuration registers designed for VCC operation. It provides general-purpose remote I/O expansion for most microcontroller families via the I?C interface (serial clock (SCL), serial data (SDA)). The PCA9554 consists of one 8-bit configuration (input or output selection), input, output and polarity inversion (active high or active low) registers. At power on, the I/Os are configured as inputs with a weak pull up to VCC. However, the system master can enable the I/Os as either inputs or outputs by writing to the I/O configuration bits. The data for each input or output is kept in the corresponding input or output register. The polarity of the input port register can be inverted with the polarity inversion register. All registers can be read by the system master.