It has, by now, become well known that the Lego RCX-module is eminently suitable for experimenting with such things as robotics. But once the designs grow beyond simple experimentation it quickly becomes obvious that the number of inputs and outputs that this control module provides, are rather insufficient. That’s why Elektor Electronics presents the I2Cinterface for this Lego brick. An entirely new world is opened up: in principle, no fewer than 128 I2C-devices may be connected to the bus!The RCX, the ‘intelligent’ component of the Lego Robotics Invention System, which forms part of the Lego Mindstorms program, is eminently suitable to serve a as the basis of various automation applications. Apart from the programming that is still required, it is very easy to assemble, for example, a small robot together with ‘normal’ Lego parts. However powerful or modular the design of the RCX-module may be, when more things have to be controlled or measured than are possible with the three inputs and the three outputs, you’re out of luck…