【国民技术N32G457评测】温度大气压检测

jinglixixi

【国民技术N32G457评测】温度大气压检测 [复制链接]

BMP085是一款数字式传感器，可直接获得环境的温度及大气压检测值，故使用起来十分好用，将它与OLED屏相配合即可构成一个小巧的温湿度大气压检测器。

BMP085 和OLED屏与开发板的连接关系如下：

OLED_CLK ---PE3

OLED_DIN ---PE3

BMP085_CLK---PE5

BMP085_DIN ---PE5

为模拟I2C实现高低电平的输出其定义的语句为：

#define SCL_Clr() GPIOE->PBC = GPIO_PIN_3

#define SCL_Set() GPIOE->PBSC = GPIO_PIN_3

#define SDA_Clr() GPIOE->PBC = GPIO_PIN_5

#define SDA_Set() GPIOE->PBSC = GPIO_PIN_5

BMP085进行输入与输出模式设置的函数分别为：

void IIC_INPUT_MODE_SET()
{
    GPIO_InitType GPIO_InitStructure;
    RCC_EnableAPB2PeriphClk(RCC_APB2_PERIPH_GPIOE, ENABLE);
    GPIO_InitStructure.Pin = GPIO_PIN_5;
    GPIO_InitStructure.GPIO_Mode  = GPIO_Mode_IPD;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_InitPeripheral(GPIOE, &GPIO_InitStructure);
}


void IIC_OUTPUT_MODE_SET()
{
    GPIO_InitType GPIO_InitStructure;
    RCC_EnableAPB2PeriphClk(RCC_APB2_PERIPH_GPIOE, ENABLE);
    GPIO_InitStructure.Pin = GPIO_PIN_5;
    GPIO_InitStructure.GPIO_Mode  = GPIO_Mode_Out_PP;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_InitPeripheral(GPIOE, &GPIO_InitStructure);
}

BMP085的初始化函数为：

void BMP085_Init(void)
{
    GPIO_InitType GPIO_InitStructure;
    RCC_EnableAPB2PeriphClk(RCC_APB2_PERIPH_GPIOE, ENABLE);
    GPIO_InitStructure.Pin = GPIO_PIN_3|GPIO_PIN_5;
    GPIO_InitStructure.GPIO_Mode  = GPIO_Mode_Out_PP;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_InitPeripheral(GPIOE, &GPIO_InitStructure);
}

BMP085的收发字节数据的函数分别为：

void BMP085_Send_Byte(char txd)
{
    char t;
    IIC_OUTPUT_MODE_SET();
    SCL_Clr();
    for(t=0;t<8;t++)
    {
        if((txd&0x80)>>7)
            SDA_Set();
        else
            SDA_Clr();
        txd<<=1;
        SysTick_Delay_Us (2);
        SCL_Set();
        SysTick_Delay_Us (2);
        SCL_Clr();
        SysTick_Delay_Us (2);
    }
}

char BMP085_Read_Byte(unsigned char ack)
{
      unsigned char i,receive=0;
      IIC_INPUT_MODE_SET();
      for(i=0;i<8;i++)
      {
        SCL_Clr();
        SysTick_Delay_Us (2);
        SCL_Set();
        receive<<=1;
        if(IIC_SDA_IN) receive++;
        SysTick_Delay_Us (1);
      }
      if(!ack)
          BMP085_NAck();
      else
          BMP085_Ack();
      return receive;
}

BMP085读取检测值的函数为：

void bmp085Convert()
{
      unsigned int ut;
      unsigned long up;
      long x1, x2, b5, b6, x3, b3, p;
      unsigned long b4, b7;
      ut = bmp085ReadTemp();
      up = bmp085ReadPressure();
      x1 = (((long)ut - (long)ac6)*(long)ac5) >> 15;
      x2 = ((long) mc << 11) / (x1 + md);
      b5 = x1 + x2;
      temperature = ((b5 + 8) >> 4);
      b6 = b5 - 4000;
      x1 = (b2 * (b6 * b6)>>12)>>11;
      x2 = (ac2 * b6)>>11;
      x3 = x1 + x2;
      b3 = (((((long)ac1)*4 + x3)<<OSS) + 2)>>2;
      x1 = (ac3 * b6)>>13;
      x2 = (b1 * ((b6 * b6)>>12))>>16;
      x3 = ((x1 + x2) + 2)>>2;
      b4 = (ac4 * (unsigned long)(x3 + 32768))>>15;
      b7 = ((unsigned long)(up - b3) * (50000>>OSS));
      if (b7 < 0x80000000)
        p = (b7<<1)/b4;
      else
        p = (b7/b4)<<1;
      x1 = (p>>8) * (p>>8);
      x1 = (x1 * 3038)>>16;
      x2 = (-7357 * p)>>16;
      pressure = p+((x1 + x2 + 3791)>>4);
}

实现温度、大气压检测及显示的主程序为：

int main(void)
{
    LedInit(PORT_GROUP1, LED5_PIN);
    BMP085_Init();
    Init_BMP085();
    OLEDInit();
    OLED_Init();
    OLED_Clear();
    OLED_ShowString(20,0,"N32G457 TEST",16);
    OLED_ShowString(20,2,"OLED & BMP085",16);
    OLED_ShowString(20,4,"t=     C",16);
    OLED_ShowString(20,6,"p=       KPa",16);
    while(1)
    {
         bmp085Convert();
         OLED_ShowNum(44,4,temperature/10,3,16);
         OLED_ShowNum(44,6,pressure/100,5,16);
         LedBlink(PORT_GROUP1, LED5_PIN);
         SysTick_Delay_Ms(1000);
    }
}

经程序的编译和下载，其运行效果如下图所示。