STM32F103 serial port configuration and printing using printf

First, configure the serial port clock:

    // USART1 clock enable 

    RCC_APB2PeriphClockCmd(

    RCC_APB2Periph_USART1 |

    RCC_APB2Periph_GPIOA |

    RCC_APB2Periph_AFIO, ENABLE);

Then configure the port, configure the serial port, and enable it.

void USART1_Init(void)

{

/////// config the gpio

    GPIO_InitTypeDef GPIO_InitStructure;

    /* PA9 USART1_Tx */ 

    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9; //Configure the send port

    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz; 

    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP; // 

    GPIO_Init(GPIOA, &GPIO_InitStructure); 

    /* PA10 USART1_Rx  */ 

    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10; //Configure the receiving port

    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;// 

    GPIO_Init(GPIOA, &GPIO_InitStructure);

//////////////

    USART_InitTypeDef USART_InitStructure;//

    USART_InitStructure.USART_BaudRate = 115200; //Configure baud rate

    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;//

    //config clock

    USART_ClockInitTypeDef   USART_ClockInitStructure;

    USART_ClockInitStructure.USART_Clock = USART_Clock_Disable;     

    USART_ClockInitStructure.USART_CPOL = USART_CPOL_Low;      

    USART_ClockInitStructure.USART_CPHA = USART_CPHA_2Edge;      

    USART_ClockInitStructure.USART_LastBit = USART_LastBit_Disable; 

    USART_ClockInit(USART1, &USART_ClockInitStructure);

    /* Configure USART1 */ 

    USART_Init(USART1, &USART_InitStructure);//

    /* Enable the USART1 */ 

    USART_Cmd(USART1, ENABLE);//??1? 

}

The serial port is configured. In order to use printf for printing, it needs to be redirected:

Add the following code in stm32f10x_usart.c:

int fputc(int ch, FILE *f)

{

 /* Write a character to USART */

 USART_SendData(USART1, (uint8_t) ch);

 /* Loop until sending is complete*/

 while (USART_GetFlagStatus(USART1, USART_FLAG_TC) == RESET);

 return ch;

}

Add the stdio.h header file to stm32f10x_usart.h, and then add the declaration int fputc(int ch, FILE *f);

Finally, check "Use MicroLIB" under Target in the settings.