I've written an I2C slave, which supports transmitting/receiving multiple bytes and repeated start. A PCA9555 GPIO implementation is included: http://www.frank-buss.de/vhdl/i2c_slave-0.3.zip It was successfully tested with two different hardware I2C masters and I2C standard and fast mode. I'm not sure if it is a good idea to setup a new project for it or if it should be integrated into the existing I2C project. And I wonder if a Wishbone interface needs more gates and makes the usage more complicated (the PCA9555 implementation demonstrates how easy it is to use this core). -- Frank Buss, fb at frank-buss.de http://www.frank-buss.de, http://www.it4-systems.de