UART-STM32
The purpose of communication: to transfer the data of one device to another device, to expand the hardware system
Communication protocol: to formulate the rules of communication, and the two sides of the communication will send and receive data according to the rules of the agreement
The first step is to turn on the clock, and turn on the clock of the USART and GPIO that need to be used. The
second step is to initialize the GPIO, configure TX as a multiplexed output, and configure RX as an input. The
third step is to configure the USART and use a structure directly. can put here