In the last chapter, we introduced the functions and hardware components of an IoT product (the Smart Light). In this chapter, we will move on to its driver development. Among the four layers of the IoT architecture, the perception & control layer is intended to control objects, for example to switch on/off lights, or to open/close a curtain. To control different objects, corresponding hardware drivers are required, such as LED drivers and motor control drivers. The perception & control layer can be combined with cloud computing, data mining, fuzzy recognition, and other AI technologies on the upper layer, to analyse and process massive data and information, smartly control objects, and realise real-time control, precise management, and scientific decision-making.