怎样通过CH340G转TTL与PC的USB进行通信的

USB转TTL串口（printf）


单片机的串口可以转为TTL电平，可以转232，可以转485。本篇讲的是通过CH340G转TTL电平与PC的USB通信。单片机串口发送数据到电脑的USB，printf作用：做项目时，单片机通过串口往电脑发数据。程序的修改分为四步，具体如下。


Step1:初始化串口


void USART1_Init(void)


{


  /* USARTx configured as follow:


        - BaudRate = 115200 baud  


        - Word Length = 8 Bits


        - One Stop Bit


        - No parity


        - Hardware flow control disabled (RTS and CTS signals)


        - Receive and transmit enabled


  */


  USART_InitStructure.USART_BaudRate = 115200;


  USART_InitStructure.USART_WordLength = USART_WordLength_8b;


  USART_InitStructure.USART_StopBits = USART_StopBits_1;


  USART_InitStructure.USART_Parity = USART_Parity_No;


  USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;


  USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;




/* Enable GPIO clock */


  RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_AFIO, ENABLE);




/* Enable UART clock */


RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1, ENABLE);




/* Configure USART Tx as alternate function push-pull */


  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;


  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9;


  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;


  GPIO_Init(GPIOA, &GPIO_InitStructure);





  /* Configure USART Rx as input floating */


  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;


  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10;


  GPIO_Init(GPIOA, &GPIO_InitStructure);





  /* USART configuration */


  USART_Init(USART1, &USART_InitStructure);


   


  /* Enable USART */


  USART_Cmd(USART1, ENABLE);


注意两点：1.一些宏定义的替换2.增加stm32f10x_usart.c文件


Step2:引用头文件stdio.h


Step3:定义PUTCHAR_PROTOTYPE


Step4:勾选MicroLIB