USART Strategy

I was about to use USART (Universal Synchronous Asynchronous Receiver Transmitter) or SC (Serial Communications Interface) on STM32F4 (32-bit microcontrollers) for a particular academic project few years back at the University of Bologna, Italy. The code and the git upload is not in a good shape as I was new to programming and github then. I choose to keep this on my repository to recall my early encounter to the beauty of programming. This code might be a help to the biginners working with MCU's.