IoT applications are becoming increasingly important. One of the most important requirements in this network is low energy consumption. In this study, a low energy consuming SoC for IoT applications was designed. For this purpose, open source softcore processors and operating systems were examined. LEON3 and OpenRISC are two important platforms that can be used in this field. Energy consumption analyzes of these two systems were obtained and compared. FreeRTOS operating system was installed and examined on the LEON3 processor. Thus, a technical analysis support was provided to the designers from this point of view.