软件i2c驱动bmp180，输出气压数据严重不准确

膜蛤 · 发表于 2018-8-21 20:49:15

参照官方pdf文档做了一个bmp180输出温度气压程序，现在温度能正常，气压就是不准确，怎么调都不行，请大佬们帮忙看看哪里出了问题
[mw_shl_code=c,true]u8 oss=0x01;
bmp_data bmp_180;

static u16 bmp_tworead(u8 msb,u8 lsb)
{
u8 s1,s2;
s1=I2C_ReadByte(bmp180_addr,msb);
s2=I2C_ReadByte(bmp180_addr,lsb);
return((s1<<8)|(s2&0xFF));
}

void bmp_getcalib(void)
{
bmp_180.ac1=(short)bmp_tworead(0xAA,0xAB);
bmp_180.ac2=(short)bmp_tworead(0xAC,0xAD);
bmp_180.ac3=(short)bmp_tworead(0xAE,0xAF);
bmp_180.ac4=bmp_tworead(0xB0,0xB1);
bmp_180.ac5=bmp_tworead(0xB2,0xB3);
bmp_180.ac6=bmp_tworead(0xB4,0xB5);
bmp_180.b1=(short)bmp_tworead(0xB6,0xB7);
bmp_180.b2=(short)bmp_tworead(0xB8,0xB9);
bmp_180.mb=(short)bmp_tworead(0xBA,0xBB);
bmp_180.mc=(short)bmp_tworead(0xBC,0xBD);
bmp_180.md=(short)bmp_tworead(0xBE,0xBF);

}

u8 bmp180_init(void)
{
bmp_getcalib();
if(I2C_ReadByte(bmp180_addr,0xD0)==0x55)
{
return(0);
}else{return(1);}
}

void bmp_getdata(long *temp,long *pres)
{
u8 xlsb;
u16 mlsb;
long x1,x2,x3,b3,b5,b6,p;
unsigned long b4,b7;
I2C_WriteByte(bmp180_addr,0xF4,0x2E);//开始测温度
delay_ms(5);
bmp_180.ut=(long)bmp_tworead(0xF6,0xF7);//读出ut

x1=(bmp_180.ut-bmp_180.ac6)*bmp_180.ac5/32768;
x2=bmp_180.mc*2048/(x1+bmp_180.md);
b5=x1+x2;
*temp=(b5+8)/16;//计算出温度

I2C_WriteByte(bmp180_addr,0xF4,0x34+(oss<<6));//开始测气压
delay_ms(8);
mlsb=bmp_tworead(0xF6,0xF7);
xlsb=I2C_ReadByte(bmp180_addr,0xF8);
bmp_180.up=(mlsb<<8+xlsb)>>(8-oss);//读出up

b6=b5-4000;
x1=(bmp_180.b2*(b6*b6/4096))/2048;
x2=bmp_180.ac2*b6/2048;
x3=x1+x2;
b3=((bmp_180.ac1*4+x3)<<oss+2)/4;
x1=bmp_180.ac3*b6/8192;
x2=(bmp_180.b1*(b6*b6/4096))/65536;
x3=((x1+x2)+2)/4;
b4=bmp_180.ac4*(unsigned long)(x3+32768)/32768;
b7=((unsigned long)bmp_180.up-b3)*(50000>>oss);
if(b7<0x80000000)
{
p=(b7*2)/b4;
}else
{
p=(b7/b4)*2;
}
x1=(p/256)*(p/256);
x1=(x1*3038)/65536;
x2=(-7357*p)/65536;
p=p+(x1+x2+3791)/16;
*pres=p;

}[/mw_shl_code]

BST-BMP180-DS000-12.pdf (635.94 KB, 下载次数: 56)

膜蛤 · 发表于 2018-8-21 20:49:16

重写了一遍，现在正常了，暂时没找到原因
[mw_shl_code=c,true]#include "bmp180.h"

u8 oss=0;
s16 AC1=0,AC2=0,AC3=0,B1=0,B2=0,MB=0,MC=0,MD=0;
u16 AC4=0,AC5=0,AC6=0;

static u16 BMP180_Read(u8 addr)
{
      u16 temp=0;
      u8 tempH=0,tempL=0;
      tempH=I2C_ReadByte(0x77,addr);
      tempL=I2C_ReadByte(0x77,addr+1);
      temp=(tempH<<8)|(tempL&0xFF);
      return temp;
}

static void bmp_getcalib(void)
{
      AC1=BMP180_Read(0XAA);
      AC2=BMP180_Read(0XAC);
      AC3=BMP180_Read(0XAE);
      AC4=BMP180_Read(0XB0);
      AC5=BMP180_Read(0XB2);
      AC6=BMP180_Read(0XB4);
      B1=BMP180_Read(0XB6);
      B2=BMP180_Read(0XB8);
      MB=BMP180_Read(0XBA);
      MC=BMP180_Read(0XBC);
      MD=BMP180_Read(0XBE);
}

u8 bmp180_init(void)
{
      if(I2C_ReadByte(0x77,0xD0)==0x55)
      {
            bmp_getcalib();
            return(0);
      }else{return(1);}
}

void BMP180_Calculation(s32 *temp,double *pres)
{
      s32 UT=0,UP=0;
      s32 T=0;
      s32 P=0,X1=0,X2=0,X3=0,B3=0,B5=0,B6=0,B7=0;
      u32 B4=0;

      I2C_WriteByte(0x77,0xF4,0x2E);
      delay_ms(6);
      UT=BMP180_Read(0xF6);
      I2C_WriteByte(0x77,0xF4,0x34);
      delay_ms(7);
      UP=BMP180_Read(0xf6);

      X1 =(((s32)UT-(s32)AC6)*(s32)AC5)>>15;
      X2 = ((s32)MC<<11)/(X1+MD);
      B5 = X1 + X2;
      T = (B5 + 8)>>4;
      *temp=T;

      B6 = B5 - 4000;
      X1 = (B2*(B6*B6>>12))>>11;
      X2 = AC2*B6>>11;
      X3 = X1 + X2;
      //B3 = (((((s32)AC1)*4 + X3)<<oss)+2)>>2;
      B3 = (((AC1<<2)+X3)+2)>>2;
      X1 = AC3*B6>>13;
      X2 = (B1*((B6*B6)>>12))>>16;
      X3 = ((X1+X2)+2)>>2;
      B4 = AC4*(u32)(X3 + 32768)>>15;
      //B7 = ((u32)(UP - B3)*(50000>>oss));
      B7 = (u32)(UP - B3)*50000;

      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;
      P += (X1+X2+3791)>>4;
      *pres=P;
}
[/mw_shl_code]