'2) Sensor/Barometric_Pressure'에 해당되는 글 1건

  1. 2016.09.17 Barometric Pressure Altitude BMP180 (BMP180) [S074]

Barometric Pressure Altitude BMP180 (BMP180) [S074]



https://www.youtube.com/watch?v=XPFTwPbBXpM


*GitHub : https://github.com/rdiot/rdiot-s074.git


* Specs

Measuring the absolute pressure of the enviroment using a digital barometer such as this has some interesting applications. By converting the pressure measured into altitude, you have a reliable sensor for determining the height of your robot, plane or projectile!

Using a sensor as capable as the BMP180 you can achieve accurary of 1m, with noise of only 17cm in ultra high resolution noise. The device will operate at only 0.3uA meaning low current draw for battery powered applications.


The BMP180 comes fully calibrated and ready to use. As the device operates over I2C we've added optional I2C pull ups that can be enabled using the PU (pull up) jumper on the board for your convenience and ease during breadboarding.


Using I2C, the device provides pressure and temperature as 16bit values, which are used along with calibration data within the device are used to provide a temperature compensated altitude calculation.


This device is really easy to use, if your thinking of using it with an  then you need to check out our BMP180 tutorial! 

Features:

1.8V to 3.6V Supply Voltage

Low power consumption - 0.5uA at 1Hz

I2C interface

Max I2C Speed: 3.5Mhz

Very low noise - up to 0.02hPa (17cm)

Full calibrated

Pressure Range: 300hPa to 1100hPa (+9000m to -500m)

Weight: 1.18g

Size: 21mm x 18mm


* Contents

- Connect

VIN ----- 5V

GND ------ GND

SCL ----- A5

SDA ----- A4


- Library : https://github.com/jrowberg/i2cdevlib

 : Sample Test : BMP085, I2Cdev


- Key Code

#include <Wire.h> 

#include <LiquidCrystal_I2C.h>

 

LiquidCrystal_I2C lcd(0x27,20,4);  // LCD2004

 

// Arduino Wire library is required if I2Cdev I2CDEV_ARDUINO_WIRE implementation

// is used in I2Cdev.h

#include "Wire.h"

 

// I2Cdev and BMP085 must be installed as libraries, or else the .cpp/.h files

// for both classes must be in the include path of your project

#include "I2Cdev.h"

#include "BMP085.h"

 

// class default I2C address is 0x77

// specific I2C addresses may be passed as a parameter here

// (though the BMP085 supports only one address)

BMP085 barometer;

 

float temperature;

float pressure;

float altitude;

int32_t lastMicros;

 

#define LED_PIN 13 // (Arduino is 13, Teensy is 11, Teensy++ is 6)

bool blinkState = false;

 

void setup()

{

  lcd.init();  // initialize the lcd 

  lcd.backlight();

  lcd.print("start LCD2004");

 

  // join I2C bus (I2Cdev library doesn't do this automatically)

  Wire.begin();

  barometer.initialize();

 

  pinMode(LED_PIN, OUTPUT);

  delay(1000);

 

  lcd.clear();

}

 

void loop()

{

 

  lcd.setCursor(0,0);

  lcd.print("S074:BMP180");

 

    // request temperature

    barometer.setControl(BMP085_MODE_TEMPERATURE);

    

    // wait appropriate time for conversion (4.5ms delay)

    lastMicros = micros();

    while (micros() - lastMicros < barometer.getMeasureDelayMicroseconds());

 

    // read calibrated temperature value in degrees Celsius

    temperature = barometer.getTemperatureC();

 

    // request pressure (3x oversampling mode, high detail, 23.5ms delay)

    barometer.setControl(BMP085_MODE_PRESSURE_3);

    while (micros() - lastMicros < barometer.getMeasureDelayMicroseconds());

 

    // read calibrated pressure value in Pascals (Pa)

    pressure = barometer.getPressure();

 

    // calculate absolute altitude in meters based on known pressure

    // (may pass a second "sea level pressure" parameter here,

    // otherwise uses the standard value of 101325 Pa)

    altitude = barometer.getAltitude(pressure);

 

    // display measured values if appropriate

    lcd.setCursor(0,1);

    lcd.print("Temperature=" + (String)temperature + "  ");

 

    lcd.setCursor(0,2);

    lcd.print("Pressure=" + (String)pressure + "  ");

 

    lcd.setCursor(0,3);

    lcd.print("Altitude=" + (String)altitude + "  ");

 

    // blink LED to indicate activity

    blinkState = !blinkState;

    digitalWrite(LED_PIN, blinkState);

    

    // delay 100 msec to allow visually parsing blink and any serial output

    delay(100); 

}

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