Tom,
Not used to doing this so I hope I get it right.
Program
</********* Title: Barometer.ino **********/
/*Working with: Arduino Mega
- Author: including #inclusive's Bosch Sensortec
- & modified by HCS
- Date: 16th October 2015
- This Program is held in my "Sketchbook"
- The DHT Program is held in "Libraries".
- The FULL program will be in "Sketchbook"
- using Barometer as the Principal Title
- Pins will be Barometer A4&5. DHT21 using A2
- The principle program is to be bare boned to basics.
- Included will be dusk to dawn Intruder lighting.
- driven by a SH300.
*/
#include <SFE_BMP180.h>
#include <Wire.h>
// You will need to create an SFE_BMP180 object, here called "pressure":
SFE_BMP180 pressure;
#define ALTITUDE 38.0 /* Altitude of 39, Sandacre Road
Manchester, England,UK. In m's*/
void setup()
{
Serial.begin(9600);
Serial.println("REBOOT");
// Initialize the sensor (it is important to get calibration values stored on the device).
if (pressure.begin())
Serial.println("BMP180 init success");
else
{
// Oops, something went wrong, this is usually a connection problem,
// see the comments at the top of this sketch for the proper connections.
Serial.println("BMP180 init fail\n\n");
while(1); // Pause forever.
}
}
void loop()
{
char status;
double T,P,p0,a;
// Loop here getting pressure readings every 10 seconds.
// If you want sea-level-compensated pressure, as used in weather reports,
// you will need to know the altitude at which your measurements are taken.
// We're using a constant called ALTITUDE in this sketch:
Serial.println();
Serial.print("Provided altitude = ");
Serial.print(ALTITUDE,0);
Serial.print(" meters, ");
Serial.print(ALTITUDE*3.28084,0);
Serial.println(" feet");
// This measures altitude, and not pressure, you will instead need
// So provide a known baseline pressure. This is shown at the end of the sketch.
// Scipts state: You must first get a temperature measurement to perform a pressure reading.
// So start a temperature measurement:
// If request is successful, the number of ms to wait is returned.
// If request is unsuccessful, 0 is returned.
status = pressure.startTemperature();
if (status != 0)
{
// Wait for the measurement to complete:
delay(status);
// Retrieve the completed temperature measurement:
// Note that the measurement is stored in the variable T.
// Function returns 1 if successful, 0 if failure.
status = pressure.getTemperature(T);
if (status != 0)
{
// Print out the measurement:
Serial.print("temperature: ");
Serial.print(T,2);
Serial.print(" deg C, ");
Serial.print((9.0/5.0)*T+32.0,2);
Serial.println(" deg F");
// Start a pressure measurement:
// The parameter is the oversampling setting, from 0 to 3 (highest res, longest wait).
// If request is successful, the number of ms to wait is returned.
// If request is unsuccessful, 0 is returned.
status = pressure.startPressure(3);
if (status != 0)
{
// Wait for the measurement to complete:
delay(status);
// Retrieve the completed pressure measurement:
// Note that the measurement is stored in the variable P.
// Note also that the function requires the previous temperature measurement (T).
// (If temperature is stable, you can do one temperature measurement for a number of pressure measurements.)
// Function returns 1 if successful, 0 if failure.
status = pressure.getPressure(P,T);
if (status != 0)
{
// Print out the measurement:
Serial.print("absolute pressure: ");
Serial.print(P,2);
Serial.print(" mb, ");
Serial.print(P*0.0295333727,2);
Serial.println(" inHg");
// The pressure sensor returns abolute pressure, which varies with altitude.
// To remove the effects of altitude, use the sealevel function and your current altitude.
// This number is commonly used in weather reports.
// Parameters: P = absolute pressure in mb, ALTITUDE = current altitude in m.
// Result: p0 = sea-level compensated pressure in mb
// I'm at 38 meters above sea level so:
p0 = pressure.sealevel(P,ALTITUDE);
Serial.print("relative (sea-level) pressure: ");
Serial.print(p0,2);
Serial.print(" mb, ");
Serial.print(p0*0.0295333727,2);
Serial.println(" inHg");
// On the other hand, if you want to determine your altitude from the pressure reading,
// use the altitude function along with a baseline pressure (sea-level or other).
// Parameters: P = absolute pressure in mb, p0 = baseline pressure in mb.
// Result: a = altitude in m.
a = pressure.altitude(P,p0);
Serial.print("Computed altitude: ");
Serial.print(a,0);
Serial.print(" meters, ");
Serial.print(a*3.28084,0);
Serial.println(" feet");
}
else Serial.println("Error retrieving pressure measurement\n");
}
else Serial.println("Error starting pressure measurement\n");
}
else Serial.println("Error retrieving temperature measurement\n");
}
else Serial.println("Error starting temperature measurement\n");
delay(5000); // Pause for 5 seconds.
}
ChrisPSR
