The MCP23008-E/SO is a 8bit I/O expander with high speed I2C interface in 18 lead SOIC package. This I/O expander provides 8bit, general purpose parallel I/O expansion for I2C bus applications. The MCP23008 consists of multiple 8bit configuration registers for input, output and polarity selection. The system master can enable I/Os as either inputs or outputs by writing I/O configuration bits. Data for each input or output is kept in corresponding input or output register. The polarity of input port register can be inverted with polarity inversion register. All registers can be read by system master.