上传BMP085气压计的文档，想问问这里的计算公式是什么意...

小笨蛋

这是提供的参考程序。一直看不懂这个公式是怎么来的。。基于什么原理？？
void read_BMP085(void)
{

           long ut;
        long up;
        long x1, x2, b5, b6, x3, b3, p;
        unsigned long b4, b7;

        ut = bmp085ReadTemp();           // 读取温度
//        ut = bmp085ReadTemp();           // 读取温度
        up = bmp085ReadPressure();  // 读取压强
//        up = bmp085ReadPressure();  // 读取压强
        x1 = ((long)ut - ac6) * 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) + 2)/4;
        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 * 2) / b4 ;
           else  
                    p = (b7 / b4) * 2;
        x1 = (p >> 8) * (p >> 8);
        x1 = (x1 * 3038) >> 16;
        x2 = (-7357 * p) >> 16;
         pressure = p + ((x1 + x2 + 3791) >> 4);
}


void  Init_BMP085(void)
{
        ac1 = Single_Read(BMP085_Addr,0xAA);
        ac1 = (ac1<<8)|Single_Read(BMP085_Addr,0xAB);

    ac2 = Single_Read(BMP085_Addr,0xAC);
        ac2 = (ac2<<8)| Single_Read(BMP085_Addr,0xAD);

        ac3 = Single_Read(BMP085_Addr,0xAE);
        ac3 = (ac3<<8)| Single_Read(BMP085_Addr,0xAF);

        ac4 = Single_Read(BMP085_Addr,0xB0);
        ac4 = (ac4<<8)| Single_Read(BMP085_Addr,0xB1);

        ac5 = Single_Read(BMP085_Addr,0xB2);
        ac5 = (ac5<<8)| Single_Read(BMP085_Addr,0xB3);

        ac6 = Single_Read(BMP085_Addr,0xB4);
        ac6 = (ac6<<8)| Single_Read(BMP085_Addr,0xB5);

        b1 = Single_Read(BMP085_Addr,0xB6);
        b1 = (b1<<8)| Single_Read(BMP085_Addr,0xB7);

        b2 = Single_Read(BMP085_Addr,0xB8);
        b2 = (b2<<8)| Single_Read(BMP085_Addr,0xB9);

        mb = Single_Read(BMP085_Addr,0xBA);
        mb = (mb<<8)| Single_Read(BMP085_Addr,0xBB);

        mc = Single_Read(BMP085_Addr,0xBC);
        mc = (mc<<8)| Single_Read(BMP085_Addr,0xBD);

        md = Single_Read(BMP085_Addr,0xBE);
        md = (md<<8)| Single_Read(BMP085_Addr,0xBF);

}

这是PDF文档

蒋盼盼

楼主测得大气压实多少Kpa啊