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。