bmp180程序，关于iic地址问题

发布于 2020-01-20 17:19:21 浏览：2116 订阅该版

* 本帖最后由 aozima 于 2020-1-20 17:48 编辑 *

在写的时候参考了这一篇文章[https://blog.csdn.net/zxh912516636/article/details/77890497](https://blog.csdn.net/zxh912516636/article/details/77890497)
根据这篇文章改的程序
使用rtthread的iic驱动框架进行编写的，在编写的时候，需要注意，iic框架程序中的地址是7位地址不是，技术文件里面的8位地址。所以使用iic框架的时候需要将地址>>1位是从机地址。
也就是说bmp180的写地址是0xee但是，在iic驱动框架中，oxee要右移一位，变成0x77 才是正确的从机地址
程序

```#include <rtthread.h>
#include <rtdevice.h>
#include <board.h>
#include "user.h"
#include "stdio.h"
#include "string.h"
#include "math.h"

#define BMP180_I2C_BUS_NAME         "i2c1"   /* 传感器连接的I2C总线设备名称 */
#define BMP180_ADDR                  0x77    /* 从机地址 */

typedef struct __BMP180
{
    short AC1;
    short AC2;
    short AC3;
    unsigned short AC4;
    unsigned short AC5;
    unsigned short AC6;
    short B1;
    short B2;
    short MB;
    short MC;
    short MD;
    long UT;
    long UP;
    long X1;
    long X2;
    long X3;
    long B3;
    unsigned long B4;
    long B5;
    long B6;
    long B7;
    long p;
    long Temp;
    float altitude;
}_bmp180;

_bmp180 bmp180;  //所有数据结构
static struct rt_i2c_bus_device *i2c_bus = RT_NULL;     /* I2C总线设备句柄 */
rt_err_t BMP180_Send_Cmd(rt_uint8_t cmd)
{
    struct rt_i2c_msg msgs;

msgs.addr = BMP180_ADDR;
    msgs.flags = RT_I2C_WR;
    msgs.len = 1;
    msgs.buf = (rt_uint8_t*)&cmd;

/* 调用I2C设备接口传输数据 */
    if (rt_i2c_transfer(i2c_bus, &msgs, 1) == 1)
    {
        return RT_EOK;
    }
    else
    {
        return -RT_ERROR;
    }
}
rt_err_t BMP180_Read_Dat(rt_uint8_t* dat)
{
    struct rt_i2c_msg msgs;

msgs.addr = BMP180_ADDR;
    msgs.flags = RT_I2C_RD;
    msgs.len = 2;
    msgs.buf = dat;

/* 调用I2C设备接口传输数据 */
    if (rt_i2c_transfer(i2c_bus, &msgs, 1) == 1)
    {
        return RT_EOK;
    }
    else
    {
        return -RT_ERROR;
    } 
}

short BMP_ReadTwoByte(rt_uint8_t date)
{
          short data;
    uint8_t msb[2];

BMP180_Send_Cmd(date);

BMP180_Read_Dat(msb);

data = msb[0]*256 + msb[1];

return data;
}
void BMP180_INIT()
{
        
          bmp180.AC1 = BMP_ReadTwoByte(0xAA);
    bmp180.AC2 = BMP_ReadTwoByte(0xAC);
    bmp180.AC3 = BMP_ReadTwoByte(0xAE);
    bmp180.AC4 = BMP_ReadTwoByte(0xB0);
    bmp180.AC5 = BMP_ReadTwoByte(0xB2);
    bmp180.AC6 = BMP_ReadTwoByte(0xB4);
    bmp180.B1  = BMP_ReadTwoByte(0xB6);
    bmp180.B2  = BMP_ReadTwoByte(0xB8);
    bmp180.MB  = BMP_ReadTwoByte(0xBA);
    bmp180.MC  = BMP_ReadTwoByte(0xBC);
    bmp180.MD  = BMP_ReadTwoByte(0xBE);
}
//写一个数据到BMP180
rt_err_t BMP_WriteOneByte(rt_uint8_t *cmd)
{
        struct rt_i2c_msg msgs;

msgs.addr = BMP180_ADDR;
    msgs.flags = RT_I2C_WR;
    msgs.len = 2;
    msgs.buf = cmd;

/* 调用I2C设备接口传输数据 */
    if (rt_i2c_transfer(i2c_bus, &msgs, 1) == 1)
    {
        return RT_EOK;
    }
    else
    {
        return -RT_ERROR;
    }
}
//从BMP180读取未修正的温度
long BMP_Read_UT(void)
{
    long temp = 0;
          rt_uint8_t ut_1[2];
          ut_1[0]=0xF4;
          ut_1[1]=0x2E; 
    BMP_WriteOneByte(ut_1);

rt_thread_mdelay(5);
    temp = (long)BMP_ReadTwoByte(0xF6);
    return temp;
}
uint8_t BMP_ReadOneByte(uint8_t ReadAddr)
{
        uint8_t data = 0;

BMP180_Send_Cmd(ReadAddr);
    BMP180_Read_Dat(&data);
    return data;
}
//从BMP180读取未修正的大气压
long BMP_Read_UP(void)
{
    long pressure = 0;
    rt_uint8_t ut_1[2];
          ut_1[0]=0xF4;
          ut_1[1]=0x34; 
    BMP_WriteOneByte(ut_1);
    rt_thread_mdelay(5);

pressure = (long)BMP_ReadTwoByte(0xF6);
    pressure = pressure + BMP_ReadOneByte(0xf8);
    pressure &= 0x0000FFFF;

return pressure;
}
//用获取的参数对温度和大气压进行修正，并计算海拔
void BMP_UncompemstatedToTrue(void)
{
    bmp180.UT = BMP_Read_UT();//第一次读取错误
    bmp180.UT = BMP_Read_UT();//进行第二次读取修正参数
    bmp180.UP = BMP_Read_UP();

bmp180.X1 = ((bmp180.UT - bmp180.AC6) * bmp180.AC5) >> 15;
    bmp180.X2 = (((long)bmp180.MC) << 11) / (bmp180.X1 + bmp180.MD);
    bmp180.B5 = bmp180.X1 + bmp180.X2;
    bmp180.Temp  = (bmp180.B5 + 8) >> 4;

bmp180.B6 = bmp180.B5 - 4000;
    bmp180.X1 = ((long)bmp180.B2 * (bmp180.B6 * bmp180.B6 >> 12)) >> 11;
    bmp180.X2 = ((long)bmp180.AC2) * bmp180.B6 >> 11;
    bmp180.X3 = bmp180.X1 + bmp180.X2;

bmp180.B3 = ((((long)bmp180.AC1) * 4 + bmp180.X3)+2) /4;
    bmp180.X1 = ((long)bmp180.AC3) * bmp180.B6 >> 13;
    bmp180.X2 = (((long)bmp180.B1) *(bmp180.B6*bmp180.B6 >> 12)) >>16;
    bmp180.X3 = ((bmp180.X1 + bmp180.X2) + 2) >> 2;
    bmp180.B4 = ((long)bmp180.AC4) * (unsigned long)(bmp180.X3 + 32768) >> 15;
    bmp180.B7 = ((unsigned long)bmp180.UP - bmp180.B3) * 50000;

if(bmp180.B7 < 0x80000000)
    {
        bmp180.p = (bmp180.B7 * 2) / bmp180.B4;     
    }
    else
    {
        bmp180.p = (bmp180.B7 / bmp180.B4) * 2;
    }

bmp180.X1 = (bmp180.p >> 8) * (bmp180.p >>8);
    bmp180.X1 = (((long)bmp180.X1) * 3038) >> 16;
    bmp180.X2 = (-7357 * bmp180.p) >> 16;

bmp180.p = bmp180.p + ((bmp180.X1 + bmp180.X2 + 3791) >> 4);

bmp180.altitude = 44330 * (1-pow(((bmp180.p) / 101325.0),(1.0/5.255)));  
}
void i2c_BMP180_example_entry(void *parameter)
{
    i2c_bus = (struct rt_i2c_bus_device*)rt_device_find(BMP180_I2C_BUS_NAME);

if(i2c_bus == RT_NULL)
    {
        rt_kprintf("can't find %s device!<br>", BMP180_I2C_BUS_NAME);
    }
                BMP180_INIT();
    while(1)
    {
                                char   msg_pub[30];

BMP_UncompemstatedToTrue();
                        
                          memset(msg_pub, 0x0, sizeof(msg_pub));
                          snprintf(msg_pub, sizeof(msg_pub),"气压: %dpa      ",bmp180.p);
                                wirte_string(2,0,msg_pub,16);
        rt_thread_mdelay(1000);
    }
}```