App note (PDF) on NXP’s Agile I/O expander, discussing its capabilities and how to use it efficiently.
I2C-bus GPIO devices are widely used and expand a control processor’s pins to 8-, 16- or 24- bits of general-purpose input or output. The characteristic of these I/O needs to be accurately known to efficiently use them in a system. This application note will explore the actual electrical characteristics of Agile I/O GPIO pins.