Hi, Thanks for your inspiration, we’ve added an interface for IO-expanders and adapted three of our hardware drivers to this interface. http://xpcc.io/api/classxpcc_1_1_gpio_expander.html There is a wrapper class for using individual pins of the expander: http://xpcc.io/api/classxpcc_1_1_gpio_expander_pin.html#details And also a wrapper for optimized access to the port or parts of it: http://xpcc.io/api/classxpcc_1_1_gpio_expander_port.html#details See the updated example on how to use of this: https://github.com/roboterclubaachen/xpcc/blob/develop/examples/stm32f4_disc... Cheers, Niklas