Abstract The purpose of this project is to develop a modular processor card which is intended to work as a platform for Kitron Development Karlskoga. The modular processor card is meant to be used as a control system in development projects, mainly in medical and industrial products. The processor card will consist of a central unit with the basic functions for a control system. Furthermore there will be complete modules with machine commodity and programming, to pick exactly the necessary functions for a specific application. With consideration to the specification of the development and the main unit, I chose an adequate microprocessor (AT90CAN32) as core and interface circuits to stated border areas. The construction is first completed in the program MultiSim and then remade in the program OrCAD Capture. The programming language C was used in the software model.