程序如下：为什么超级终端没有反应？

Question

#include "stm32f10x.h"#include <stdio.h>int main(void){GPIO_InitTypeDef GPIO_InitStructure;USART_InitTypeDef USART_InitStructure;RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_AFIO, ENABLE);RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1, ENABLE);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);GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10;GPIO_Init(GPIOA, &GPIO_InitStructure);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;USART_Init(USART1, &USART_InitStructure);USART_Cmd(USART1, ENABLE);USART_ClearFlag(USART1, USART_FLAG_TC);printf("\r\n this is a printf demo \r\n");while(1){}}int fputc(int ch, FILE *f){USART_SendData(USART1, (unsigned char) ch);while (!(USART1->SR & USART_FLAG_TXE));return (ch);}

Answer 1

如果你也是用printf只是输出，那么下面这些代码就够用了
以下代码直接替换main（）中的部分，功能是完整可用的
/* Enable GPIO clock */
main()

{
RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1 |
RCC_APB2Periph_GPIOA, 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);

/* 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_Tx;

USART_Init(USART1, &USART_InitStructure);

/* Enable USART */
USART_Cmd(USART1, ENABLE);

/* Output a message on Hyperterminal using printf function */
printf("\n\rA B C D E F G 0 1 2 3 4 5\n\r");

/* Infinite loop */
while (1)
{

}
}

补充：3.5版本的库在启动文件中已经设置了系统时钟，固定为72M，所以不用去再设置它了

Answer 2

先确认硬件以及连线没有问题。
有条件的话用示波器量一下输出波形。