BMP180 大气压强传感器
模拟气体传感器 (SKU:DFR0049)
目录
1 概述
2 技术指标
3 引脚定义
4 特性曲线
5 简单例程
5.1 标准代码
概述
如今在电子市场上，具有GPS功能的导航设备越来越多。借助全球卫星定位系统可以判定设备的经纬平面所处位置，但是无法得知目前的海拔高度。不过这一难题随着微型高精度气压传感器的出现而有望得以解决。
Bosch Sensortec开发出一款智能，超小体积，高精度数字传感器BMP180，适合智能的高精度测量和数据采集，输出高精度的压力（或高度）和温度测量数据。可与加速度计相互搭配，在没有GPS讯号的环境下，提供可靠的楼层侦测能力，以实现三维(3D)室内导航。
本传感器可以检测：温度，大气压强，海拔高度。
技术指标
工作电压：5V
工作范围：-40～+85 ℃
压强精度：0.12hPa/m
接口类型：4pin 排针和 1.27间距 IDC10座
引脚定义
如图，模块共有4个引脚，从上到下是5V，GND，SCL,SDA。模块可以通过I2C和单片机通信，5V供电。
特性曲线
简单例程
目标：测出当前环境下的大气压强和计算出芯片的海拔高度
1.先连接芯片与单片机（通过I2C接口），按照如下图的方式连接。
2.然后UNO通过usb与PC电脑连接。
3.拷贝以下的代码烧录进单片机。
标准代码
/**************************************************************************************/
/**********************DFRobot.com*****************************/
/write by Tom Riddler Jun.16.14/
/if you got any progream,please contact me terminaterfxy@hotmail.com/
#include <Wire.h>
#define BMP180ADD 0xEE>>1 // I2C address of BMP180
//write is (0xEE) read is (0xEF)
unsigned char OSS;
/**********************MSB LSB******/
int ac1; // 0xAA 0xAB
int ac2; // 0xAC 0xAD
int ac3; // 0xAE 0xAE
unsigned int ac4; // 0xB0 0xB1
unsigned int ac5; // 0xB2 0xB3
unsigned int ac6; // 0xB4 0xB5
int b1; // 0xB6 0xB7
int b2; // 0xB8 0xB9
int mb; // 0xBA 0xBB
int mc; // 0xBC 0xBD
int md; // 0xBE 0xBF
float temperature;
double pressure;
double pressure2;
long b5;
double altitude;
void setup()
{
Serial.begin(9600);
Wire.begin();
OSS = 2; // Oversampling Setting 0: single 1: 2 times 2: 4 times 3: 8 times
BMP180start();
}
void loop()
{
calculate();
show();
delay(1000);
}
/** calculate centure **/
void calculate()
{
temperature = bmp180GetTemperature(bmp180ReadUT());
temperature = temperature*0.1;
pressure = bmp180GetPressure(bmp180ReadUP());
pressure2 = pressure/101325;
pressure2 = pow(pressure2,0.19029496);
altitude = 44330(1-pressure2); //altitude = 44330(1-(pressure/101325)^0.19029496);
}
/** print reslut **/
void show()
{
Serial.print("Temperature: ");
Serial.print(temperature, 1); //10 hexadecimal
Serial.println(" C");
Serial.print("Pressure: ");
Serial.print(pressure, 0); //10 hexadecimal
Serial.println(" Pa");
Serial.print("altitude:");
Serial.print(altitude);
Serial.println("m");
}
/BMP180 satrt program/
void BMP180start()
{ /MSB/
ac1 = bmp180ReadDate(0xAA); //get full data
ac2 = bmp180ReadDate(0xAC);
ac3 = bmp180ReadDate(0xAE);
ac4 = bmp180ReadDate(0xB0);
ac5 = bmp180ReadDate(0xB2);
ac6 = bmp180ReadDate(0xB4);
b1 = bmp180ReadDate(0xB6);
b2 = bmp180ReadDate(0xB8);
mb = bmp180ReadDate(0xBA);
mc = bmp180ReadDate(0xBC);
md = bmp180ReadDate(0xBE);
}
/BMP180 temperature Calculate/
short bmp180GetTemperature(unsigned int ut)
{
long x1, x2;
x1 = (((long)ut - (long)ac6)(long)ac5) >> 15; //x1=((ut-ac6)ac5)/(2^15)
x2 = ((long)mc << 11)/(x1 + md); //x2=(mc*2^11)/(x1+md)
b5 = x1 + x2; //b5=x1+x2
return ((b5 + 8)>>4); //t=(b5+8)/(2^4)
}
/BMP180 pressure Calculate/
long bmp180GetPressure(unsigned long up)
{
long x1, x2, x3, b3, b6, p;
unsigned long b4, b7;
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;
p += (x1 + x2 + 3791)>>4;
return p;
}
/*** Read 1 bytes from the BMP180 ***/
int bmp180Read(unsigned char address)
{
unsigned char data;
Wire.beginTransmission(BMP180ADD);
Wire.write(address);
Wire.endTransmission();
Wire.requestFrom(BMP180ADD, 1);
while(!Wire.available());
return Wire.read();
}
/*** Read 2 bytes from the BMP180 ***/
int bmp180ReadDate(unsigned char address)
{
unsigned char msb, lsb;
Wire.beginTransmission(BMP180ADD);
Wire.write(address);
Wire.endTransmission();
Wire.requestFrom(BMP180ADD, 2);
while(Wire.available()<2);
msb = Wire.read();
lsb = Wire.read();
return (int) msb<<8 | lsb;
}
/*** read uncompensated temperature value ***/
unsigned int bmp180ReadUT()
{
unsigned int ut;
Wire.beginTransmission(BMP180ADD);
Wire.write(0xF4); // Write 0x2E into Register 0xF4
Wire.write(0x2E); // This requests a temperature reading
Wire.endTransmission();
delay(5); // Wait at least 4.5ms
ut = bmp180ReadDate(0xF6); // read MSB from 0xF6 read LSB from (16 bit)
return ut;
}
/*** Read uncompensated pressure value from BMP180 ***/
unsigned long bmp180ReadUP()
{
unsigned char msb, lsb, xlsb;
unsigned long up = 0;
Wire.beginTransmission(BMP180ADD);
Wire.write(0xF4); // Write 0x34+(OSS<<6) into register 0xF4
Wire.write(0x34 + (OSS<<6)); // 0x34+oss*64
Wire.endTransmission();
delay(2 + (3<<OSS)); // Wait for conversion, delay time dependent on OSS
Wire.beginTransmission(BMP180ADD);
Wire.write(0xF6); // Read register 0xF6 (MSB), 0xF7 (LSB), and 0xF8 (XLSB)
Wire.endTransmission();
Wire.requestFrom(BMP180ADD, 3);
while(Wire.available() < 3); // Wait for data to become available
msb = Wire.read();
lsb = Wire.read();
xlsb = Wire.read();
up = (((unsigned long) msb << 16) | ((unsigned long) lsb << 8) | (unsigned long) xlsb) >> (8-OSS);//16 to 19 bit
return up;
}
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