The P90CL301 is a highly integrated 16/32 bit micro-controller especially suitable for applications requiring low voltage and low power consumption. It is fully software compatible with the 68000. Furthermore, it provides both standard as well as advanced peripheral functions on-chip. One of these peripheral functions is the I2C bus. This report describes worked-out driver software (written in C) to program the P90CL301 I2C interface. It also contains interface software routines offering the user a quick start in writing a complete I2C system application.