Other flags provide error information include parity, framing, and overrun
errors which should be checked in a robust implementation.
In order to transmit a character, the application software must wait for
the transmit data รีจีสเตอร์ to be empty and then write the character to be
transmitted to that รีจีสเตอร์. The state of the transmit data รีจีสเตอร์ is determined
by checking the USART_FLAG_TXE flag of the USART status รีจีสเตอร์.
The following code implements a basic putchar procedure utilizing USART1.