用USART串口通信在电脑上用XCOM波特率要减半

Zapateado · 发表于 2017-8-7 10:59:48

//代码
#include "stm32f10x.h"
#include "usart.h"
#include <stdio.h>

int main(void)
{
Usart_Init(115200);
while (1)
{
printf("\r\nI am in while loop\r\n");
}
}

//usart.c
#include "usart.h"
#include "stm32f10x.h"
#include <stdio.h>

int fputc(int ch, FILE *f)
{
while((USART1->SR&0X40)==0);//循环发送,直到发送完毕
USART1->DR = (u8) ch;
return ch;
}

void Usart_Init(unsigned int bound)
{
GPIO_InitTypeDef GPIO_InitStructure;
USART_InitTypeDef USART_InitStructure;
NVIC_InitTypeDef NVIC_InitStructure;

RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1 | RCC_APB2Periph_GPIOA, ENABLE);

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;

GPIO_Init(GPIOA, &GPIO_InitStructure);
//rxd PA10 浮空输入
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;

GPIO_Init(GPIOA, &GPIO_InitStructure);

NVIC_InitStructure.NVIC_IRQChannel = USART1_IRQn;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority  = 3;
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 3;

NVIC_Init(&NVIC_InitStructure);

USART_InitStructure.USART_BaudRate = bound;
  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_ITConfig(USART1,USART_IT_RXNE, ENABLE);
USART_Cmd(USART1, ENABLE);

  printf("\n\rUSART is now ok!\n\r");
}

//usart.h
#ifndef __USART_H
#define __USART_H

#include "stm32f10x.h"
void Usart_Init(unsigned int bound);

#endif

不知道为什么波特率会减半比如我这里设置的115200波特率下载到板子上打开串口调试工具要调到57600波特率才能正常接收信息

正点原子 · 发表于 2017-8-7 10:59:49

你主时钟不对

Zapateado · 发表于 2017-8-8 08:45:29

正点原子发表于 2017-8-8 02:04
你主时钟不对

原子哥我用正点原子的例程直接烧进去不会出现这种现象我自己写的这个就要波特率减半是主时钟不对么

正点原子 · 发表于 2017-8-14 02:39:47

Zapateado 发表于 2017-8-8 08:45
原子哥我用正点原子的例程直接烧进去不会出现这种现象我自己写的这个就要波特率减半是主时钟不对么

是的

Zapateado · 发表于 2017-8-24 17:49:46

正点原子发表于 2017-8-14 02:39
是的

请问怎么调这个网上的大概是叫我改HSE_VALUE 再改PLL倍频系数
参考http://www.21ic.com/jichuzhishi/mcu/timer/2017-07-17/730067.html
我改了之后发现没什么用正点原子例程里也没改这两个就是正常的系统时钟了
还有精英板STM32F103ZET6的HSE晶振是8MHZ的吧