PCA9554DB

The PCA9554DB is an 8-bit I/O Expander for the two-line bidirectional bus (I?C) is designed for 2.3 to 5.5V 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. The system master can reset the PCA9554 in the event of a timeout or other improper operation by utilizing the power-on reset feature.