stm32f407与PC之间USART通信不成功，求大虾们指教啊

只看该作者 · 2015-8-3 18:23

本帖最后由 kevin2512 于 2015-8-3 18:29 编辑

stm32f407 discover开发板与PC之间USART通信不成功，按复位键才出个乱码，一个y字母上面两点的乱码。完全不对啊，复位键一直按住不放，就一直出乱码，松开啥都不出。求大虾们指教
下面是我写的代码，全在main.c文件中，没有用到中断什么的。
串口调试助手，波特率，COM口，等参数都设置正确。
不过，我在stm32f4xx.h和system_stm32f4xx.c中改了两个参数，一个是HSE我改成8M（板子上是8M），原来是25M。还有PLLM把25改成8，其他地方没动过。

#include "stm32f4xx.h"
#include "stdio.h"
#define PUTCHAR_PROTOTYPE int fputc(int ch,FILE *f)

void USART6_Config(void);
int main(void)
{

RCC_ClocksTypeDef RCC_Clocks;
RCC_GetClocksFreq(&RCC_Clocks);

  USART6_Config();
  printf("\r\n this is a printf demo \r\n");
  printf("\r\n welcome to use discovery board: \r\n");

  while (1)
  {
  }
}
void USART6_Config(void)
{
GPIO_InitTypeDef GPIO_InitStruct ;
USART_InitTypeDef USART_InitStruct ;
/*使能USART1外设时钟（挂在APB2上）和GPIOA外设时钟（挂在AHB1上）*/
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOC, ENABLE);
RCC_APB2PeriphResetCmd(RCC_APB2Periph_USART6, ENABLE);

GPIO_PinAFConfig(GPIOC,GPIO_PinSource6,GPIO_AF_USART6);  //Tx
GPIO_PinAFConfig(GPIOC,GPIO_PinSource7,GPIO_AF_USART6);//Rx

/*初始化GPIOA*/

GPIO_InitStruct.GPIO_Pin=GPIO_Pin_6 | GPIO_Pin_7;
GPIO_InitStruct.GPIO_Mode=GPIO_Mode_AF;
GPIO_InitStruct.GPIO_Speed=GPIO_Speed_50MHz;
GPIO_InitStruct.GPIO_OType=GPIO_OType_PP;
GPIO_InitStruct.GPIO_PuPd=GPIO_PuPd_UP;
GPIO_Init(GPIOC,&GPIO_InitStruct);

/*USART1初始化配置*/
USART_InitStruct.USART_BaudRate=115200;/*波特率为115200bps*/
USART_InitStruct.USART_WordLength=USART_WordLength_8b;/*发送字长为8位字长*/
USART_InitStruct.USART_StopBits=USART_StopBits_1;/*停止位为1*/
USART_InitStruct.USART_Parity=USART_Parity_No;/*无奇偶校验位*/
USART_InitStruct.USART_HardwareFlowControl=USART_HardwareFlowControl_None;  /*不采用硬件流*/
USART_InitStruct.USART_Mode=USART_Mode_Rx|USART_Mode_Tx; /*串口双工模式*/
USART_Init(USART6,&USART_InitStruct);
USART_Cmd(USART6,ENABLE); /*使能USART1*/
}

/*实现重定向printf函数，而重写的fputc()这个C标准库函数*/
int fputc(int ch,FILE *f)
{
   /*将printf内容发往串口*/
   USART_SendData(USART6,(uint8_t)ch);
   while(USART_GetFlagStatus(USART6,USART_FLAG_TC)!=SET)/*检测串口数据发送完成标志位TC的值*/
   {}                                                    /*TC=SET(1),表示发送发成*/
   return ch;
}
/*---------------------------------------下面是断言，不用管--------------------------------------------------------------------------------------*/
#ifdef  USE_FULL_ASSERT
void assert_failed(uint8_t* file, uint32_t line)
{
  /* User can add his own implementation to report the file name and line number,
   ex: printf("Wrong parameters value: file %s on line %d\r\n", file, line) */

  /* Infinite loop */
  while (1)
  {
  }
}
#endif

只看该作者 · 2015-8-5 13:01

错误找出来了，我晕死啊，那个APB2的时钟使能，把函数搞成复位了。

，调了我好几天。总是在最简单的地方出错啊。还难以发现

3万 · 2015-8-3 20:22

一直发数据看看，看波特率对不对；

只看该作者 · 2015-8-3 20:36

mmuuss586 发表于 2015-8-3 20:22
一直发数据看看，看波特率对不对；

我想是不是时钟频率参数设置的不对呢，因为库函数里给的外部晶振频率是25M,我的板子上焊接的是8M。
#define PLL_M    8 //在system_stm32f4xx.c中，这里把25改成8；

#if !defined  (HSE_VALUE)
  #define HSE_VALUE ((uint32_t)8000000) /*!< Value of the External oscillator in Hz */
#endif /* HSE_VALUE */    在stm32f4xx.h中，这里把25000000改成的8000000；
不知道其他地方还要修改不？
串口助手里参数都没错的，波特率我用的是main.c中设置的115200，就是出不来那两行printf；

1万 · 2015-8-5 17:49

#include "usart.h"

#ifdef __GNUC__
  /* With GCC/RAISONANCE, small printf (option LD Linker->Libraries->Small printf
   set to 'Yes') calls __io_putchar() */
  #define PUTCHAR_PROTOTYPE int __io_putchar(int ch)
#else
  #define PUTCHAR_PROTOTYPE int fputc(int ch, FILE *f)
#endif /* __GNUC__ */

/*******************************************************************************
* Function Name  : USART_Configuration
* Description : Configure Open_USART
* Input       : None
* Output       : None
* Return       : None
* Attention    : None
*******************************************************************************/
void USART_Configuration(void)
{
  GPIO_InitTypeDef GPIO_InitStructure;
  USART_InitTypeDef USART_InitStructure;

  RCC_AHB1PeriphClockCmd(Open_USART_TX_GPIO_CLK,ENABLE);
  RCC_AHB1PeriphClockCmd(Open_USART_RX_GPIO_CLK,ENABLE);

  #ifdef USART1_OPEN
    RCC_APB2PeriphClockCmd(Open_USART_CLK,ENABLE);
  #else
    RCC_APB1PeriphClockCmd(Open_USART_CLK,ENABLE);
  #endif

  GPIO_PinAFConfig(Open_USART_TX_GPIO_PORT, Open_USART_TX_SOURCE, Open_USART_TX_AF);
  GPIO_PinAFConfig(Open_USART_RX_GPIO_PORT, Open_USART_RX_SOURCE, Open_USART_RX_AF);

  /*
  *  Open_USART_TX -> PA9 , Open_USART_RX -PA10
  */
  GPIO_InitStructure.GPIO_Pin = Open_USART_TX_PIN;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
  GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;

  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
  GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;
  GPIO_Init(Open_USART_TX_GPIO_PORT, &GPIO_InitStructure);

  GPIO_InitStructure.GPIO_Pin = Open_USART_RX_PIN;
  GPIO_InitStructure.GPIO_OType = GPIO_OType_OD;
  GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
  GPIO_Init(Open_USART_RX_GPIO_PORT, &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
*/

  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(Open_USART, &USART_InitStructure);
  /* Enable the Open_USART Transmit interrupt: this interrupt is generated when the
   Open_USART transmit data register is empty */
  USART_ITConfig(Open_USART,USART_IT_RXNE,ENABLE);

  USART_Cmd(Open_USART, ENABLE);

}

void USART_NVIC_Config(void)
{
  NVIC_InitTypeDef NVIC_InitStructure;

  /* Enable the USARTx Interrupt */
  NVIC_InitStructure.NVIC_IRQChannel = Open_USART_IRQn;
  NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
  NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
  NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
  NVIC_Init(&NVIC_InitStructure);
}

/* Use no semihosting */
#if 1
#pragma import(__use_no_semihosting)
struct __FILE
{
int handle;
};
FILE __stdout;

_sys_exit(int x)
{
x = x;
}
#endif

/**
  * @brief  Retargets the C library printf function to the USART.
  * @param  None
  * @retval None
  */
PUTCHAR_PROTOTYPE
{
  /* Place your implementation of fputc here */
  /* e.g. write a character to the USART */
  USART_SendData(Open_USART, (uint8_t) ch);

  /* Loop until the end of transmission */
  while (USART_GetFlagStatus(Open_USART, USART_FLAG_TC) == RESET)
  {}

  return ch;
}
给你一个范例，自己研究下吧

stm32f407与PC之间USART通信不成功，求大虾们指教啊

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