本帖最后由 jinglixixi 于 2023-7-19 12:04 编辑
#申请原创#
BMP085是一种可对环境温度及大气压进行检测的传感器，它体积小易于同0.96寸的LCD一起构成一个便携式的环境状态检测装置。 该装置的整体电路构成及连接如图1所示：
整体构成
BMP085是一种采用I2C接口工作的器件，故占用的引脚资源极少，在使用时它与开发板的连接关系为： SCL----PA1 SDA----PA0
所用引脚输出高低电平的定义为： #defineSDA_Set1() GPIO_SetPinLevel(GPIOA,GPIO_PIN0, GPIO_LEVEL_HIGH) #defineSDA_Clr1() GPIO_SetPinLevel(GPIOA,GPIO_PIN0, GPIO_LEVEL_LOW)
#define SCL_Set1() GPIO_SetPinLevel(GPIOA, GPIO_PIN1,GPIO_LEVEL_HIGH) #defineSCL_Clr1() GPIO_SetPinLevel(GPIOA,GPIO_PIN1, GPIO_LEVEL_LOW)
为读取数据所作的相应定义为： #defineSDA_IN GPIO_GetPinLevel(GPIOA,GPIO_PIN0)
BMP085的初始化函数为： 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);
}
在以GPIO口模拟I2C收发字节数据的函数为： void BMP085_Send_Byte(char txd)
{
char t;
OUTPUT_MODE_SET();
SCL_Clr1();
for(t=0;t<8;t++)
{
if((txd&0x80)>>7)
SDA_Set1();
else
SDA_Clr1();
txd<<=1;
udelay(1);
SCL_Set1();
udelay(1);
SCL_Clr1();
udelay(1);
}
}
char BMP085_Read_Byte(unsigned char ack)
{
unsigned char i,receive=0;
INPUT_MODE_SET();
for(i=0;i<8;i++)
{
SCL_Clr1();
udelay(1);
SCL_Set1();
receive<<=1;
if(SDA_IN) receive++;
udelay(1);
}
if(!ack)
BMP085_NAck();
else
BMP085_Ack();
return receive;
}
BMP085读取温度和大气压数据的函数为： 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);
}
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数据变换处理的函数为： 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;
temperature1 = ((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);
}
实现测试效果的主程序为： int main(void)
{
InitDelay();
InitDebug();
GPIO_LedInit();
TIMER_PrdInit();
GPIO_OLEDInit();
OLED_Init();
OLED_Clear();
OLED_ShowString(10,0,"AC7802x Test",16);
OLED_ShowString(10,2,"BMP085",16);
BMP085_Init();
Init_BMP085();
OLED_ShowString(0,4,"t= C",16);
OLED_ShowString(0,6,"p= KPa",16);
mdelay(500);
while (1)
{
bmp085Convert();
OLED_ShowNum(24,4,temperature1/10,3,16);
OLED_ShowNum(24,6,pressure/100,5,16);
OLED_ShowNum(24,4,temperature1/10,3,16);
OLED_ShowNum(24,6,pressure/100,5,16);
mdelay(500);
}
}
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