Grove - Barometer Sensor (BMP180)

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Introduction

This is a Grove module for the Bosch BMP180 high-precision, low-power digital barometer. The BMP180 offers a pressure measuring range of 300 to 1100 hPa with an accuracy down to 0.02 hPa in advanced resolution mode. It’s based on piezo-resistive technology for high accuracy, ruggedness and long term stability. The chip only accepts 1.8V to 3.6V input voltage. However, with outer circuit added, this module becomes compatible with 3.3V and 5V. Therefore, it can be used on Arduino/Seeeduino or Seeeduino Stalker without modification.It is designed to be connected directly to a micro-controller via the I2C bus.


400px-Barometer(BMP180).jpg


Features

Digital two wire (I2C) interface Wide barometric pressure range Flexible supply voltage range Ultra-low power consumption Low noise measurement Factory-calibrated -40 to +85°C operational range, ±2°C temperature accuracy I2C address: 0x77 Application Ideas

Enhancement of GPS navigation Indoor and outdoor navigation Leisure and sports Weather forecast Vertical velocity indication (rise/sink speed) Specifications

Item Min Typical Max Unit Voltage 3 5 5.5 VDC Current 1.1 / 20 uA Pressure Range 300 / 1100 hPa Faster I2C data transfer / / 3.4 MHZ Dimension 40.1*20.2*9.7 mm Usage

With Arduino Barometric condition is one of the criteria used to predict coming change in weather and deduce altitude above sea level. Here is a demo to show you how to read the barometric data from this Grove - Barometer Sensor (BMP180). 1. Connect it to IIC port of Seeeduino or Grove - Base Shield via a Grove cable. And connect Arduino to PC via a USB cable. 2. Download the library(the barometer library is shared by Grove - Barometer Sensor (BMP180) and Grove - Barometer Sensor(BMP085));Unzip it into the libraries file of Arduino IDE by the path: ..\arduino-1.0.1\libraries. 3. Create a new Arduino sketch and paste the codes below to it or open the code directly by the path:File -> Example ->Barometer_Sensor->Barometer_Sensor. /* Barometer demo V1.0

  • Based largely on code by Jim Lindblom
  • Get pressure, altitude, and temperature from the BMP085.
  • Serial.print it out at 9600 baud to serial monitor.
  • By:http://www.simgin-chip.com
  • /
  1. include "Barometer.h"
  2. include <Wire.h>

float temperature; float pressure; float atm; float altitude; Barometer myBarometer; void setup(){

 Serial.begin(9600);
 myBarometer.init();
 

}

void loop() {

  temperature = myBarometer.bmp085GetTemperature(myBarometer.bmp085ReadUT()); //Get the temperature, bmp085ReadUT MUST be called first
  pressure = myBarometer.bmp085GetPressure(myBarometer.bmp085ReadUP());//Get the temperature
  altitude = myBarometer.calcAltitude(pressure); //Uncompensated calculation - in Meters 
  atm = pressure / 101325; 
 
 Serial.print("Temperature: ");
 Serial.print(temperature, 2); //display 2 decimal places
 Serial.println("deg C");
 Serial.print("Pressure: ");
 Serial.print(pressure, 0); //whole number only.
 Serial.println(" Pa");
 Serial.print("Ralated Atmosphere: ");
 Serial.println(atm, 4); //display 4 decimal places
 Serial.print("Altitude: ");
 Serial.print(altitude, 2); //display 2 decimal places
 Serial.println(" m");
 Serial.println();
 delay(1000); //wait a second and get values again.

} 4. Open the serial monitor to receive the sensor's data including temperature, barometric pressure value, relative atmosphere pressure and altitude.


Barometer Sensor.jpg


The following is a reference graph plotting out the relationship between altitude above sea level and barometric pressure.



Pressure and Altitude.jpg



With Raspberry Pi 1.You should have got a raspberry pi and a grovepi or grovepi+. 2.You should have completed configuring the development enviroment, otherwise follow here. 3.Connection Plug the sensor to grovepi socket i2c-x(1~3) by using a grove cable. 4.Navigate to the demos' directory:

  cd yourpath/GrovePi/Software/Python/grove_barometer/adafruit

To see the code

  nano grove_i2c_barometic_sensor_example.py   # "Ctrl+x" to exit #
  1. !/usr/bin/python

import smbus import RPi.GPIO as GPIO

  1. import grovepi

from grove_i2c_barometic_sensor import BMP085

  1. ===========================================================================
  2. Example Code
  3. ===========================================================================
  1. Initialise the BMP085 and use STANDARD mode (default value)
  2. bmp = BMP085(0x77, debug=True)

bmp = BMP085(0x77, 1)

  1. To specify a different operating mode, uncomment one of the following:
  2. bmp = BMP085(0x77, 0) # ULTRALOWPOWER Mode
  3. bmp = BMP085(0x77, 1) # STANDARD Mode
  4. bmp = BMP085(0x77, 2) # HIRES Mode
  5. bmp = BMP085(0x77, 3) # ULTRAHIRES Mode

rev = GPIO.RPI_REVISION if rev == 2 or rev == 3:

   bus = smbus.SMBus(1)

else:

   bus = smbus.SMBus(0)

temp = bmp.readTemperature()

  1. Read the current barometric pressure level

pressure = bmp.readPressure()

  1. To calculate altitude based on an estimated mean sea level pressure
  2. (1013.25 hPa) call the function as follows, but this won't be very accurate
  3. altitude = bmp.readAltitude()
  1. To specify a more accurate altitude, enter the correct mean sea level
  2. pressure level. For example, if the current pressure level is 1023.50 hPa
  3. enter 102350 since we include two decimal places in the integer value

altitude = bmp.readAltitude(101560)

print "Temperature: %.2f C" % temp print "Pressure:  %.2f hPa" % (pressure / 100.0) print "Altitude:  %.2f m" % altitude 5.Run the demo.

  sudo python grove_i2c_barometic_sensor_example.py

6.Result


600px-Grovepi barometer sensor 00.png


File:BMP180.pdf