BMP180 I2C 气压传感器树莓派接入指南

简介

Bosch BMP180 是一款高精度数字气压传感器，通过 I2C 通信。本指南将教你如何将其接线到树莓派、启用 I2C 总线，并使用现成的 Python 脚本读取温度和气压。

模块概览

模块为紧凑的 15×13 mm PCB，带 5 排针。大多数模块引脚顺序相同，但接线前请核对板上标签。

引脚定义与接线

按下表将模块连接到树莓派 GPIO 排针（P1），文中也提供了面包板接线简图。

设备上电后，运行 i2cdetect -y 1 应显示地址 0x77。

启用 I2C 总线

树莓派默认禁用 I2C，运行 sudo raspi-config 选择 Interface Options → I2C → Yes，然后重启。

Python 示例代码

以下脚本演示如何从 BMP180 读取温度（°C）和气压（mbar），利用传感器内部的校准数据提供准确结果。

#!/usr/bin/python
import smbus
import time
from ctypes import c_short

DEVICE = 0x77  # 默认 I2C 地址
bus = smbus.SMBus(1)  # Pi 2 及后续机型使用总线 1

def convertToString(data):
    return str((data[1] + (256 * data[0])) / 1.2)

def getShort(data, index):
    return c_short((data[index] << 8) + data[index + 1]).value

def getUshort(data, index):
    return (data[index] << 8) + data[index + 1]

def readBmp180Id(addr=DEVICE):
    REG_ID = 0xD0
    chip_id, chip_version = bus.read_i2c_block_data(addr, REG_ID, 2)
    return chip_id, chip_version

def readBmp180(addr=DEVICE):
    REG_CALIB = 0xAA
    REG_MEAS = 0xF4
    REG_MSB = 0xF6
    REG_LSB = 0xF7
    CRV_TEMP = 0x2E
    CRV_PRES = 0x34
    OVERSAMPLE = 3

    cal = bus.read_i2c_block_data(addr, REG_CALIB, 22)
    AC1 = getShort(cal, 0)
    AC2 = getShort(cal, 2)
    AC3 = getShort(cal, 4)
    AC4 = getUshort(cal, 6)
    AC5 = getUshort(cal, 8)
    AC6 = getUshort(cal, 10)
    B1 = getShort(cal, 12)
    B2 = getShort(cal, 14)
    MB = getShort(cal, 16)
    MC = getShort(cal, 18)
    MD = getShort(cal, 20)

    # 读取温度
    bus.write_byte_data(addr, REG_MEAS, CRV_TEMP)
    time.sleep(0.005)
    msb, lsb = bus.read_i2c_block_data(addr, REG_MSB, 2)
    UT = (msb << 8) + lsb

    # 读取气压
    bus.write_byte_data(addr, REG_MEAS, CRV_PRES + (OVERSAMPLE << 6))
    time.sleep(0.04)
    msb, lsb, xsb = bus.read_i2c_block_data(addr, REG_MSB, 3)
    UP = ((msb << 16) + (lsb << 8) + xsb) >> (8 - OVERSAMPLE)

    # 计算温度
    X1 = ((UT - AC6) * AC5) >> 15
    X2 = (MC << 11) / (X1 + MD)
    B5 = X1 + X2
    temperature = (B5 + 8) >> 4

    # 计算气压
    B6 = B5 - 4000
    B62 = (B6 * B6) >> 12
    X1 = (B2 * B62) >> 11
    X2 = (AC2 * B6) >> 11
    X3 = X1 + X2
    B3 = (((AC1 * 4 + X3) << OVERSAMPLE) + 2) >> 2
    X1 = AC3 * B6 >> 13
    X2 = (B1 * B62) >> 16
    X3 = X1 + X2
    B4 = (AC4 * (X3 + 32768)) >> 15
    B7 = (UP - B3) * (50000 >> OVERSAMPLE)
    P = (B7 * 2) / B4
    X1 = (P >> 8) * (P >> 8)
    X1 = (X1 * 3038) >> 16
    X2 = (-7357 * P) >> 16
    pressure = P + ((X1 + X2 + 3791) >> 4)

    return temperature / 10.0, pressure / 100.0

def main():
    chip_id, chip_version = readBmp180Id()
    print("Chip ID :", chip_id)
    print("Version :", chip_version)
    temperature, pressure = readBmp180()
    print("Temperature :", temperature, "C")
    print("Pressure :", pressure, "mbar")

if __name__ == "__main__":
    main()

下载与运行

直接将脚本保存到树莓派：

wget https://bitbucket.org/MattHawkinsUK/rpispy-misc/raw/master/python/bmp180.py

赋予执行权限并运行：

chmod +x bmp180.py
./bmp180.py

延伸资源

• BMP180 官方数据手册
• 树莓派 GPIO 参考指南