Uncontrolled fires are responsible for many harmful damages and human losses. Hence, the design of a system in order to reduce such problems may be considered relevant. The use of real-time operating systems can present a possibility to achieve significant results and improvements in fire alarm projects, considering that fires are examples of critical time systems in which the time of response is extremely important. In the proposed project, an algorithm was developed by using Arduino Nano and FreeRTOS open source kernel in order to accomplish such task in a reduced scale project. Some tests, such as jitter, latency, and worst case response time are also carried out to evaluate the performance of the real-time system proposed in the present project.