This application note describes how to use the “STR71x_Calculation.xls” file which is intended as a tool to assist in the configuration of the STR71x clocks and baud rates. The STR71x microcontroller contains a variety of peripherals running at different frequencies. Some peripherals have a prescaler to adjust their working frequency, but some others don't and need a specific frequency to run correctly. The file “STR71x_Calculation.xls“ calculates all the working frequencies and shows the re- lated register values for each peripheral. Note: This application note doesn’t substitute the fact that it is mandatory to read the refer- ence manual before the use of this tool.