【AutoChips MCU评测报告】+BMP085气温气压检测

BMP085是一款可测量气温、气压的I2C器件，它具有体积小、易于使用的特点。

BH1750与MCU的连接关系为：

SCL——PA7

SDA——PA8

为使 BMP085有效工作，所作的相关定义语句如下：

#define SCL_Set()      GPIO_SetPinBits(GPIO_PA7)      // PA7      

#define SCL_Clr()      GPIO_ResetPinBits(GPIO_PA7)        

#define SDA_Set()      GPIO_SetPinBits(GPIO_PA8)      // PA8

#define SDA_Clr()      GPIO_ResetPinBits(GPIO_PA8)   

#define IIC_SDA_IN     GPIO_GetPinValue(GPIO_PA8)

#define IIC_INPUT_MODE_SET()   GPIO_SetDir(GPIO_PA8, 0)

#define IIC_OUTPUT_MODE_SET()  GPIO_SetDir(GPIO_PA8, 1)

使 BMP085工作的辅助函数有：

复制

void BMP085_Start(void)       

{

IIC_OUTPUT_MODE_SET();

SDA_Set();         

SCL_Set();          

udelay(5);           

SDA_Clr();        

udelay(5);  

SCL_Clr();

}



void BMP085_Stop(void)

{

IIC_OUTPUT_MODE_SET();

SDA_Clr();             

SCL_Clr();

udelay(5);    

SCL_Set();

udelay(5);

SDA_Set();  

udelay(5);

}

读取气温的函数为：

复制

long bmp085ReadTemp(void)

{

BMP085_Start();                 

BMP085_Send_Byte(BMP085_SlaveAddress);   

while(BMP085_Wait_Ack()){}

BMP085_Send_Byte(0xF4);                  

while(BMP085_Wait_Ack()){}

BMP085_Send_Byte(0x2E);       

while(BMP085_Wait_Ack()){}

BMP085_Stop();                  

mdelay(10);

return (long) Multiple_read(0xF6);

}

读取气压的函数为：

复制

long bmp085ReadPressure(void)

{

long pressure = 0;

BMP085_Start();                  

BMP085_Send_Byte(BMP085_SlaveAddress);  

while(BMP085_Wait_Ack()){}

BMP085_Send_Byte(0xF4);                  

while(BMP085_Wait_Ack()){}

BMP085_Send_Byte(0x34);                 

while(BMP085_Wait_Ack()){}

BMP085_Stop();                   

mdelay(10);

pressure = Multiple_read(0xF6);

pressure &= 0x0000FFFF;

return pressure;

}

BMP085的初始化函数为：

复制

void Init_BMP085()

{

ac1 = Multiple_read(0xAA);

ac2 = Multiple_read(0xAC);

ac3 = Multiple_read(0xAE);

ac4 = Multiple_read(0xB0);

ac5 = Multiple_read(0xB2);

ac6 = Multiple_read(0xB4);

b1 =  Multiple_read(0xB6);

b2 =  Multiple_read(0xB8);

mb =  Multiple_read(0xBA);

mc =  Multiple_read(0xBC);

md =  Multiple_read(0xBE);

}

BMP085数值转换函数为：

复制

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);

}

实现图示效果的主函数为：

复制

int main(void)

{

InitDebug();

InitDelay();

OLED_Init();

OLED_Clear();

OLED_ShowString(0,0,"AC8711 TEST",16);

OLED_ShowString(0,2,"BMP085",16);

OLED_ShowString(0,4,"t=     C",16);

OLED_ShowString(0,6,"p=       KPa",16);

BMP085_Init();

Init_BMP085();

while(1)

{

bmp085Convert();  

printf("temperature: %d C\r\n", temperature/10);

printf("pressure: %d KPa\r\n", pressure/100);

OLED_ShowNum(24,4,temperature/10,3,16);

OLED_ShowNum(24,6,pressure/100,5,16);

mdelay(1000);

}

}

BMP085测量效果