Billion of devices are connected to the internet nowadays, more are coming in the future. Cisco assumes that 50 billion devices will be connected by 2020. It is quite difficult to manage and control the exchange of the huge amount of data generated from those connected devices. Thus the need for a new more intelligent Internet of Things (IoT) architecture for large scale networks. Based on the above needs and challenges of the IoT, Software Defined Networking (SDN) seems to be an excellent key solution. Thus, using the concepts of SDN, we aim to reduce the complexity of traditional IoT networks, this means that recent IoT networks will be more programmable, managed and controlled by software. In this work, we provide an architectural model combining SDN and IoT, and a mathematical formulation of the controller placement problem as a linear integer program optimization. At the end, we present some simulation results to show the advantages of this integration.