This report describes the process of developing an automotive CAN-FD Black-Box that uses Sigfox communication. At first, the document introduces the components and programs that have been used, explaining their reason to be and the role they play. In the same way, CAN-FD and SPI protocols are analysed too, emphasizing their behaviour. Subsequently, it catalogues and describes the different drivers that had been used. Besides, it shows step by step the different parts that establish the main file to make it more understandable. After that, the code is validated to ensure its correct performance. Finally, the modification of the main file to send Sigfox messages and accept external CAN-FD messages is presented. However, this time the validation has been done using a demonstrator that includes some CAN-FD nodes. The results are shown in a linked video which confirms the correct operation of the designed Black-Box