practic_les4_ada_usart1_rxtx

-- WeAct BlackPill STM32F411CEU6 -- GPIOC Pin13 --> LED -- -- USART1 TX -->GPIOA Pin9, RX (interrupt)-->GPIOA Pin10 -- * Minicom :"Hello Word" scrolling -- * Minicom :If ASCII char Rx < 5, Turn On LED -- * Minicom :press 3, LED On. Press 9, LED Off -- * HSI=16 MHz,APB2ENR = 16MHz -- * Bps/Par/Bits : 115200/-/8N1 -- * Hardware Flow Control