c - STM32调试时的不同结果

Question

我正在尝试使用 UART 在 1-Wire 上对数字温度计 DS18B20 进行编程，但我遇到了奇怪的问题。当我调试这个运行时没有断点的程序(或者只是运行没有调试的程序)时，我的读数约为 100°C。当我在接收温度信息之前放置断点时，它给我大约 50°c。第三个选项，当我打开这个窗口时，我可以看到 SFR 并展开 UART4 部分，它会为我提供大约 25°C 的正确读数。我有 Saleae 逻辑分析仪，在所有这 3 种情况下，它都会向我发送有效数据(大约 25°C)。我试图在断点所在的地方设置一些延迟(甚至延迟 2 秒)，但没有帮助。它给了我大约 50°C 的读数(比如有断点和未扩展的 SFR 窗口)。这可能是编程错误(我正在开始)，但这种带有扩展 SFR 窗口的操作超出了我的推理范围。我真的不知道发生了什么。我希望你能为我阐明这种情况。

我正在使用 STM32F4-Discovery 评估板并在 Atollic 4.1.0 上对其进行编程。

我的“库”文件:

#include "DS18B20_Lib.h"


void DS18B20_Init(void)
{
    //USART4 PA0
    GPIO_InitTypeDef GS;
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_UART4,ENABLE);
    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA,ENABLE);
    GPIO_PinAFConfig(GPIOA,GPIO_PinSource0,GPIO_AF_UART4);

    GS.GPIO_Mode = GPIO_Mode_AF;
    GS.GPIO_OType = GPIO_OType_PP;
    GS.GPIO_PuPd = GPIO_PuPd_UP;
    GS.GPIO_Speed = GPIO_Speed_50MHz;
    GS.GPIO_Pin = GPIO_Pin_0;
    GPIO_Init(GPIOA,&GS);

    USART_InitTypeDef US;
    US.USART_BaudRate = 115200;
    US.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
    US.USART_Mode = USART_Mode_Tx | USART_Mode_Rx;
    US.USART_Parity = USART_Parity_No;
    US.USART_StopBits = USART_StopBits_1;
    US.USART_WordLength = USART_WordLength_8b;
    USART_Init(UART4,&US);
    USART_SetAddress(UART4,0x12);
    USART_Cmd(UART4,ENABLE);
    USART_HalfDuplexCmd(UART4,ENABLE);

    USART_ITConfig(UART4,USART_IT_TXE | USART_IT_RXNE | USART_IT_TC ,ENABLE);
    /*NVIC_InitTypeDef NS;
    NS.NVIC_IRQChannel = UART4_IRQn;
    NS.NVIC_IRQChannelCmd = ENABLE;
    NS.NVIC_IRQChannelPreemptionPriority = 1;
    NS.NVIC_IRQChannelSubPriority = 1;
    NVIC_Init(&NS);*/

}

uint16_t Reset_1Wire(void)
{
    uint16_t Present;
    while (USART_GetFlagStatus(UART4, USART_FLAG_TC) == RESET);
    UART4->BRR = 0x1117;
    while (USART_GetFlagStatus(UART4, USART_FLAG_TXE) == RESET);
    USART_SendData(UART4,0xF0);
    while (USART_GetFlagStatus(UART4, USART_FLAG_RXNE) == RESET);
    Present = USART_ReceiveData(UART4);
    while (USART_GetFlagStatus(UART4, USART_FLAG_TC) == RESET);
    UART4->BRR = 0x016D;
    return Present;
}

char Read_1Wire(void)
{

    char Data=0;
    int i;
    for(i=0;i<8;i++)
    {
        while (USART_GetFlagStatus(UART4, USART_FLAG_TXE) == RESET);
        USART_SendData(UART4,0xFF);
        while (USART_GetFlagStatus(UART4, USART_FLAG_RXNE) == RESET);
        if(USART_ReceiveData(UART4)==0xFF)
            Data|=0x80;
        else Data|=0;
        if (i!=7) Data=Data>>1;
    }
    return Data;
}

void Write_1Wire(char Data)
{
    char Mask=1;
    int i;
    for(i=0;i<8;i++)
    {
        while (USART_GetFlagStatus(UART4, USART_FLAG_TXE) == RESET);
        if (Data & Mask)
            USART_SendData(UART4,0xFF);
        else
            USART_SendData(UART4,0x00);
        Mask=Mask<<1;
    }
}

uint16_t DS18B20_MeasTemp(void)
{
    uint16_t Data;
    uint16_t LSB;
    uint16_t MSB;
    Reset_1Wire();
    Write_1Wire(0xCC); //SkipRom only 1 device
    Write_1Wire(0x44);
    while(Read_1Wire()==0x00);
    Reset_1Wire();
    Write_1Wire(0xCC);
    Write_1Wire(0xBE);
   /*--------BRAKEPOINT HERE--------*/
    LSB=Read_1Wire();
    MSB=Read_1Wire();
    Data=MSB<<8|LSB;
    Reset_1Wire();
    return Data;
}

还有我的主要功能:

int main(void)
{
  char strLine[25];
  uint16_t Temperature;

  LCD_Init();
  LCD_SetColors(GREEN, BLUE);
  LCD_Clear(BLUE);
  LCD_CharSize(16);

  DS18B20_Init();

  sprintf(strLine,"%s","Temp: ");
  LCD_StringLine(20,50,(uint8_t*) strLine);
  //GPIO_Config();
  while (1)
  {
    Presence1Wire();
    Temperature = DS18B20_MeasTemp();
    if (Temperature&0xF000)
        LCD_PutChar(60,50,'-');
    else LCD_PutChar(60,50,'+');
    LCD_PutInt(68,50,(Temperature&0x0FF0)>>4);
    LCD_PutInt(72,64,(Temperature&0xF)*625);
  }

}

Answer 1

Write_1Wire(0xCC);
Write_1Wire(0xBE);

• 向 UART 发送字节但不读取。在 fifo 中接收数据。

Read_1Wire()

• 读取 fifo 中的旧数据。

uint16_t DS18B20_MeasTemp(void)
{
    uint16_t Data;
    uint16_t LSB;
    uint16_t MSB;
    Reset_1Wire();
    Write_1Wire(0xCC); //SkipRom only 1 device
    Write_1Wire(0x44);
    while(Read_1Wire() == 0x00);
    Reset_1Wire();
    Write_1Wire(0xCC);
    Write_1Wire(0xBE);
   /*--------BRAKEPOINT HERE--------*/
    // !!!!!!! Paste this
    while (USART_GetFlagStatus(UART4, USART_FLAG_RXNE) != RESET)
      USART_ReceiveData(UART4);
    // !!!!!!!
    LSB = Read_1Wire();
    MSB = Read_1Wire();
    Data = MSB << 8 | LSB;
    Reset_1Wire();
    return Data;
}