Barometric Pressure Sensor Using MS5637

[hek]

Sorry, we aren't machines that easily do diffs in our heads... :)

What exactly did you change and why?

[Myles L]

Sorry about that, I changed

#include <Adafruit_BMP085.h> changed to #include <BaroSensor.h> (Alternate library files for different baro sensor)
Adafruit_BMP085 bmp = Adafruit_BMP085(); changed to BaroSensorClass bmp = BaroSensorClass(); (BaroSensorClass is referenced in the library files)
float pressure = bmp.readSealevelPressure(205)/100; **changed to ** float pressure = bmp.getPressure(); (also referenced in the library)
float temperature = bmp.readTemperature(); changed to float temperature = bmp.getTemperature(); (same reason)
if (!bmp.begin()) {
Serial.println("Could not find a valid BMP085 sensor, check wiring!");
while (1) { } **changed to ** bmp.begin(); (Could not get the sketch to compile using the original so changed to just start the baro sensor)

Thanks again.

[hek]

If you get no output in the Serial Monitor there could be a out of (stack) memory situation.

Try adding debug prints to see where it fails.

[Myles L]

Thanks, I added debug prints after each line but still get nothing on the serial monitor. Does that mean I can assume that the problem is in the initial setup section (the code before void setup(){)?

I couldn't find a way to add debug prints to that section but any suggestions on how to are welcome.

[korttoma]

Did you try something like this:

void setup()
{
Serial.begin(115200);
delay(1000);
Serial.println("Serial begin ");

gw.begin

Edit: newermind, I don't think you can get anything from the section before setup()

[BulldogLowell]

maybe i missed it, but did you have a sketch that worked (with the appropriate libraries) at least outputting the sensor data to the serial monitor?

If you have that, post it. It will be easy to add to that the 'stuff' you need for MySensors, I believe.

[Myles L]

Yes, I have that. It is just a really a really basic sketch that prints the sensor data to a serial output. I am also very interested in the weather forecast part of the MySensors sketch which is why I was trying to mod it.

#include <Wire.h>
#include <BaroSensor.h>

void setup()
{
Serial.begin(9600);
BaroSensor.begin();
}

void loop()
{
if(!BaroSensor.isOK()) {
Serial.print("Sensor not Found/OK. Error: ");
Serial.println(BaroSensor.getError());
BaroSensor.begin(); // Try to reinitialise the sensor if we can
}
else {
Serial.print("Temperature: ");
Serial.println(BaroSensor.getTemperature());
Serial.print("Pressure: ");
Serial.println(BaroSensor.getPressure());
}
delay(1000);
}

[BulldogLowell]

@Myles-L

this compiles, but I could not test it:

#include <SPI.h>
#include <MySensor.h>  
#include <Wire.h>
#include <BaroSensor.h>

#define BARO_CHILD 0
#define TEMP_CHILD 1

unsigned long SLEEP_TIME = 60000; // Sleep time between reads (in seconds)

MySensor gw;

float lastPressure = -1;
float lastTemp = -1;
int lastForecast = -1;
const char *weather[] = {"stable","sunny","cloudy","unstable","thunderstorm","unknown"};
int minutes;
float pressureSamples[180];
int minuteCount = 0;
bool firstRound = true;
float pressureAvg[7];
float dP_dt;
boolean metric; 
MyMessage tempMsg(TEMP_CHILD, V_TEMP);
MyMessage pressureMsg(BARO_CHILD, V_PRESSURE);
MyMessage forecastMsg(BARO_CHILD, V_FORECAST);

void setup() {
  gw.begin();

  // Send the sketch version information to the gateway and Controller
  gw.sendSketchInfo("Pressure Sensor", "1.0");

  BaroSensor.begin();

  // Register sensors to gw (they will be created as child devices)
  gw.present(BARO_CHILD, S_BARO);
  gw.present(TEMP_CHILD, S_TEMP);
  metric =  gw.getConfig().isMetric;
}

void loop() 
{
  if(!BaroSensor.isOK()) 
  {
    Serial.print("Sensor not Found/OK. Error: "); 
    Serial.println(BaroSensor.getError());
    BaroSensor.begin(); // Try to reinitialise the sensor if we can
  }
  
  float pressure = BaroSensor.getPressure()/100;
  float temperature = BaroSensor.getTemperature();
  if (!metric) 
  {
    // Convert to fahrenheit
    temperature = temperature * 9.0 / 5.0 + 32.0;
  }
  
  int forecast = sample(pressure);

  Serial.print("Temperature = ");
  Serial.print(temperature);
  Serial.println(metric?" *C":" *F");
  Serial.print("Pressure = ");
  Serial.print(pressure);
  Serial.println(" Pa");
  Serial.println(weather[forecast]);


  if (temperature != lastTemp) {
    gw.send(tempMsg.set(temperature,1));
    lastTemp = temperature;
  }

  if (pressure != lastPressure) {
    gw.send(pressureMsg.set(pressure, 0));
    lastPressure = pressure;
  }

  if (forecast != lastForecast) 
  {
    gw.send(forecastMsg.set(weather[forecast]));
    lastForecast = forecast;
  }
  
  /*
   DP/Dt explanation

   0 = "Stable Weather Pattern"
   1 = "Slowly rising Good Weather", "Clear/Sunny "
   2 = "Slowly falling L-Pressure ", "Cloudy/Rain "
   3 = "Quickly rising H-Press",     "Not Stable"
   4 = "Quickly falling L-Press",    "Thunderstorm"
   5 = "Unknown (More Time needed) 
  */

  gw.sleep(SLEEP_TIME);
}

int sample(float pressure) {
	// Algorithm found here
	// http://www.freescale.com/files/sensors/doc/app_note/AN3914.pdf
	if (minuteCount > 180)
		minuteCount = 6;

	pressureSamples[minuteCount] = pressure;
	minuteCount++;

	if (minuteCount == 5) {
		// Avg pressure in first 5 min, value averaged from 0 to 5 min.
		pressureAvg[0] = ((pressureSamples[1] + pressureSamples[2]
				+ pressureSamples[3] + pressureSamples[4] + pressureSamples[5])
				/ 5);
	} else if (minuteCount == 35) {
		// Avg pressure in 30 min, value averaged from 0 to 5 min.
		pressureAvg[1] = ((pressureSamples[30] + pressureSamples[31]
				+ pressureSamples[32] + pressureSamples[33]
				+ pressureSamples[34]) / 5);
		float change = (pressureAvg[1] - pressureAvg[0]);
		if (firstRound) // first time initial 3 hour
			dP_dt = ((65.0 / 1023.0) * 2 * change); // note this is for t = 0.5hour
		else
			dP_dt = (((65.0 / 1023.0) * change) / 1.5); // divide by 1.5 as this is the difference in time from 0 value.
	} else if (minuteCount == 60) {
		// Avg pressure at end of the hour, value averaged from 0 to 5 min.
		pressureAvg[2] = ((pressureSamples[55] + pressureSamples[56]
				+ pressureSamples[57] + pressureSamples[58]
				+ pressureSamples[59]) / 5);
		float change = (pressureAvg[2] - pressureAvg[0]);
		if (firstRound) //first time initial 3 hour
			dP_dt = ((65.0 / 1023.0) * change); //note this is for t = 1 hour
		else
			dP_dt = (((65.0 / 1023.0) * change) / 2); //divide by 2 as this is the difference in time from 0 value
	} else if (minuteCount == 95) {
		// Avg pressure at end of the hour, value averaged from 0 to 5 min.
		pressureAvg[3] = ((pressureSamples[90] + pressureSamples[91]
				+ pressureSamples[92] + pressureSamples[93]
				+ pressureSamples[94]) / 5);
		float change = (pressureAvg[3] - pressureAvg[0]);
		if (firstRound) // first time initial 3 hour
			dP_dt = (((65.0 / 1023.0) * change) / 1.5); // note this is for t = 1.5 hour
		else
			dP_dt = (((65.0 / 1023.0) * change) / 2.5); // divide by 2.5 as this is the difference in time from 0 value
	} else if (minuteCount == 120) {
		// Avg pressure at end of the hour, value averaged from 0 to 5 min.
		pressureAvg[4] = ((pressureSamples[115] + pressureSamples[116]
				+ pressureSamples[117] + pressureSamples[118]
				+ pressureSamples[119]) / 5);
		float change = (pressureAvg[4] - pressureAvg[0]);
		if (firstRound) // first time initial 3 hour
			dP_dt = (((65.0 / 1023.0) * change) / 2); // note this is for t = 2 hour
		else
			dP_dt = (((65.0 / 1023.0) * change) / 3); // divide by 3 as this is the difference in time from 0 value
	} else if (minuteCount == 155) {
		// Avg pressure at end of the hour, value averaged from 0 to 5 min.
		pressureAvg[5] = ((pressureSamples[150] + pressureSamples[151]
				+ pressureSamples[152] + pressureSamples[153]
				+ pressureSamples[154]) / 5);
		float change = (pressureAvg[5] - pressureAvg[0]);
		if (firstRound) // first time initial 3 hour
			dP_dt = (((65.0 / 1023.0) * change) / 2.5); // note this is for t = 2.5 hour
		else
			dP_dt = (((65.0 / 1023.0) * change) / 3.5); // divide by 3.5 as this is the difference in time from 0 value
	} else if (minuteCount == 180) {
		// Avg pressure at end of the hour, value averaged from 0 to 5 min.
		pressureAvg[6] = ((pressureSamples[175] + pressureSamples[176]
				+ pressureSamples[177] + pressureSamples[178]
				+ pressureSamples[179]) / 5);
		float change = (pressureAvg[6] - pressureAvg[0]);
		if (firstRound) // first time initial 3 hour
			dP_dt = (((65.0 / 1023.0) * change) / 3); // note this is for t = 3 hour
		else
			dP_dt = (((65.0 / 1023.0) * change) / 4); // divide by 4 as this is the difference in time from 0 value
		pressureAvg[0] = pressureAvg[5]; // Equating the pressure at 0 to the pressure at 2 hour after 3 hours have past.
		firstRound = false; // flag to let you know that this is on the past 3 hour mark. Initialized to 0 outside main loop.
	}

	if (minuteCount < 35 && firstRound) //if time is less than 35 min on the first 3 hour interval.
		return 5; // Unknown, more time needed
	else if (dP_dt < (-0.25))
		return 4; // Quickly falling LP, Thunderstorm, not stable
	else if (dP_dt > 0.25)
		return 3; // Quickly rising HP, not stable weather
	else if ((dP_dt > (-0.25)) && (dP_dt < (-0.05)))
		return 2; // Slowly falling Low Pressure System, stable rainy weather
	else if ((dP_dt > 0.05) && (dP_dt < 0.25))
		return 1; // Slowly rising HP stable good weather
	else if ((dP_dt > (-0.05)) && (dP_dt < 0.05))
		return 0; // Stable weather
	else
		return 5; // Unknown
}

[Myles L]

Thank you so much, it is so close. Code compiles, uploads and there is output from the serial monitor but when adding the device to Vera only a repeater node gets added and not the actual pressure sensor.

The additional pressure sensor files have been uploaded to Vera.

[BulldogLowell]

put some delays in here... especially if you do not have the caps on the radio!!!

BaroSensor.begin();
// Register sensors to gw (they will be created as child devices)
gw.sendSketchInfo("Pressure Sensor", "1.0");
delay(250);
gw.present(BARO_CHILD, S_BARO);
delay(250);
gw.present(TEMP_CHILD, S_TEMP);
delay(250);
metric =  gw.getConfig().isMetric;

if that isn't enough, you can try to add a little more time to the delays....

[Myles L]

Tried delays right up to 5000 and also added a few others but unfortunately it still only presents the repeater node to Vera

[BulldogLowell]

@Myles-L

Try deleting the devices it created and starting over. Give it a new device number and try it without it being a repeating node:

change:

gw.begin();

to:

gw.begin(NULL, DEVICE_ID, false);

where you defined (added) in the header of the sketch:

#define DEVICE_ID 10 

or some other number that is non-zero and not greater than 254

[Myles L]

By adding those changes it went back to not outputting to the serial interface. I was able to get it to output again by removing the DEFINE DEVICE ID and the DEVICE ID section (not sure why that made a difference) but then it goes back to only adding a node to Vera.

Really appreciate your determination to solve this and I am learning lots along the way!

[BulldogLowell]

@Myles-L

you mind posting the code you tried last?

Can you confirm that you have deleted the Vera devices that were created (I believe you said it was a relay)

[Myles L]

I have deleted the Vera devices and I have also tried removing and re-adding the MySensors plugin in Vera. When I add the pressure sensor now it still adds as a node. Code is below:

#include <SPI.h>
#include <MySensor.h>
#include <Wire.h>
#include <BaroSensor.h>

#define BARO_CHILD 0
#define TEMP_CHILD 1

unsigned long SLEEP_TIME = 60000; // Sleep time between reads (in seconds)

MySensor gw;

float lastPressure = -1;
float lastTemp = -1;
int lastForecast = -1;
const char *weather[] = {"stable","sunny","cloudy","unstable","thunderstorm","unknown"};
int minutes;
float pressureSamples[180];
int minuteCount = 0;
bool firstRound = true;
float pressureAvg[7];
float dP_dt;
boolean metric;
MyMessage tempMsg(TEMP_CHILD, V_TEMP);
MyMessage pressureMsg(BARO_CHILD, V_PRESSURE);
MyMessage forecastMsg(BARO_CHILD, V_FORECAST);

void setup() {
gw.begin(NULL, false);

// Send the sketch version information to the gateway and Controller
gw.sendSketchInfo("Pressure Sensor", "1.0");
delay(1000);
BaroSensor.begin();
delay(1000);
// Register sensors to gw (they will be created as child devices)
gw.present(BARO_CHILD, S_BARO);
delay(1000);
gw.present(TEMP_CHILD, S_TEMP);
delay(1000);
metric = gw.getConfig().isMetric;
}

void loop()
{
if(!BaroSensor.isOK())
{
Serial.print("Sensor not Found/OK. Error: ");
Serial.println(BaroSensor.getError());
BaroSensor.begin(); // Try to reinitialise the sensor if we can
}

float pressure = BaroSensor.getPressure()/100;
float temperature = BaroSensor.getTemperature();
if (!metric)
{
// Convert to fahrenheit
temperature = temperature * 9.0 / 5.0 + 32.0;
}

int forecast = sample(pressure);

Serial.print("Temperature = ");
Serial.print(temperature);
Serial.println(metric?" *C":" *F");
Serial.print("Pressure = ");
Serial.print(pressure);
Serial.println(" Pa");
Serial.println(weather[forecast]);

if (temperature != lastTemp) {
gw.send(tempMsg.set(temperature,1));
lastTemp = temperature;
}

if (pressure != lastPressure) {
gw.send(pressureMsg.set(pressure, 0));
lastPressure = pressure;
}

if (forecast != lastForecast)
{
gw.send(forecastMsg.set(weather[forecast]));
lastForecast = forecast;
}

/*
DP/Dt explanation

0 = "Stable Weather Pattern"
1 = "Slowly rising Good Weather", "Clear/Sunny "
2 = "Slowly falling L-Pressure ", "Cloudy/Rain "
3 = "Quickly rising H-Press", "Not Stable"
4 = "Quickly falling L-Press", "Thunderstorm"
5 = "Unknown (More Time needed)
*/

gw.sleep(SLEEP_TIME);
}

int sample(float pressure) {
// Algorithm found here
// http://www.freescale.com/files/sensors/doc/app_note/AN3914.pdf
if (minuteCount > 180)
minuteCount = 6;

pressureSamples[minuteCount] = pressure;
minuteCount++;

if (minuteCount == 5) {
    // Avg pressure in first 5 min, value averaged from 0 to 5 min.
    pressureAvg[0] = ((pressureSamples[1] + pressureSamples[2]
            + pressureSamples[3] + pressureSamples[4] + pressureSamples[5])
            / 5);
} else if (minuteCount == 35) {
    // Avg pressure in 30 min, value averaged from 0 to 5 min.
    pressureAvg[1] = ((pressureSamples[30] + pressureSamples[31]
            + pressureSamples[32] + pressureSamples[33]
            + pressureSamples[34]) / 5);
    float change = (pressureAvg[1] - pressureAvg[0]);
    if (firstRound) // first time initial 3 hour
        dP_dt = ((65.0 / 1023.0) * 2 * change); // note this is for t = 0.5hour
    else
        dP_dt = (((65.0 / 1023.0) * change) / 1.5); // divide by 1.5 as this is the difference in time from 0 value.
} else if (minuteCount == 60) {
    // Avg pressure at end of the hour, value averaged from 0 to 5 min.
    pressureAvg[2] = ((pressureSamples[55] + pressureSamples[56]
            + pressureSamples[57] + pressureSamples[58]
            + pressureSamples[59]) / 5);
    float change = (pressureAvg[2] - pressureAvg[0]);
    if (firstRound) //first time initial 3 hour
        dP_dt = ((65.0 / 1023.0) * change); //note this is for t = 1 hour
    else
        dP_dt = (((65.0 / 1023.0) * change) / 2); //divide by 2 as this is the difference in time from 0 value
} else if (minuteCount == 95) {
    // Avg pressure at end of the hour, value averaged from 0 to 5 min.
    pressureAvg[3] = ((pressureSamples[90] + pressureSamples[91]
            + pressureSamples[92] + pressureSamples[93]
            + pressureSamples[94]) / 5);
    float change = (pressureAvg[3] - pressureAvg[0]);
    if (firstRound) // first time initial 3 hour
        dP_dt = (((65.0 / 1023.0) * change) / 1.5); // note this is for t = 1.5 hour
    else
        dP_dt = (((65.0 / 1023.0) * change) / 2.5); // divide by 2.5 as this is the difference in time from 0 value
} else if (minuteCount == 120) {
    // Avg pressure at end of the hour, value averaged from 0 to 5 min.
    pressureAvg[4] = ((pressureSamples[115] + pressureSamples[116]
            + pressureSamples[117] + pressureSamples[118]
            + pressureSamples[119]) / 5);
    float change = (pressureAvg[4] - pressureAvg[0]);
    if (firstRound) // first time initial 3 hour
        dP_dt = (((65.0 / 1023.0) * change) / 2); // note this is for t = 2 hour
    else
        dP_dt = (((65.0 / 1023.0) * change) / 3); // divide by 3 as this is the difference in time from 0 value
} else if (minuteCount == 155) {
    // Avg pressure at end of the hour, value averaged from 0 to 5 min.
    pressureAvg[5] = ((pressureSamples[150] + pressureSamples[151]
            + pressureSamples[152] + pressureSamples[153]
            + pressureSamples[154]) / 5);
    float change = (pressureAvg[5] - pressureAvg[0]);
    if (firstRound) // first time initial 3 hour
        dP_dt = (((65.0 / 1023.0) * change) / 2.5); // note this is for t = 2.5 hour
    else
        dP_dt = (((65.0 / 1023.0) * change) / 3.5); // divide by 3.5 as this is the difference in time from 0 value
} else if (minuteCount == 180) {
    // Avg pressure at end of the hour, value averaged from 0 to 5 min.
    pressureAvg[6] = ((pressureSamples[175] + pressureSamples[176]
            + pressureSamples[177] + pressureSamples[178]
            + pressureSamples[179]) / 5);
    float change = (pressureAvg[6] - pressureAvg[0]);
    if (firstRound) // first time initial 3 hour
        dP_dt = (((65.0 / 1023.0) * change) / 3); // note this is for t = 3 hour
    else
        dP_dt = (((65.0 / 1023.0) * change) / 4); // divide by 4 as this is the difference in time from 0 value
    pressureAvg[0] = pressureAvg[5]; // Equating the pressure at 0 to the pressure at 2 hour after 3 hours have past.
    firstRound = false; // flag to let you know that this is on the past 3 hour mark. Initialized to 0 outside main loop.
}

if (minuteCount < 35 && firstRound) //if time is less than 35 min on the first 3 hour interval.
    return 5; // Unknown, more time needed
else if (dP_dt < (-0.25))
    return 4; // Quickly falling LP, Thunderstorm, not stable
else if (dP_dt > 0.25)
    return 3; // Quickly rising HP, not stable weather
else if ((dP_dt > (-0.25)) && (dP_dt < (-0.05)))
    return 2; // Slowly falling Low Pressure System, stable rainy weather
else if ((dP_dt > 0.05) && (dP_dt < 0.25))
    return 1; // Slowly rising HP stable good weather
else if ((dP_dt > (-0.05)) && (dP_dt < 0.05))
    return 0; // Stable weather
else
    return 5; // Unknown

}

[BulldogLowell]

@BulldogLowell said:

Try this, and tell me what the serial output looks like.

Have you added a capacitor to the radio? It could be electronic...

#include <SPI.h>
#include <MySensor.h>  
#include <Wire.h>
#include <BaroSensor.h>

#define BARO_CHILD 0
#define TEMP_CHILD 1
#define DEVICE_ID 99

unsigned long SLEEP_TIME = 60000; // Sleep time between reads (in seconds)

MySensor gw;

float lastPressure = -1;
float lastTemp = -1;
int lastForecast = -1;
const char *weather[] = {"stable","sunny","cloudy","unstable","thunderstorm","unknown"};
int minutes;
float pressureSamples[180];
int minuteCount = 0;
bool firstRound = true;
float pressureAvg[7];
float dP_dt;
boolean metric; 
MyMessage tempMsg(TEMP_CHILD, V_TEMP);
MyMessage pressureMsg(BARO_CHILD, V_PRESSURE);
MyMessage forecastMsg(BARO_CHILD, V_FORECAST);

void setup() {
  gw.begin(NULL, DEVICE_ID, false);
  delay(1000);
  Serial.println("Got to GW.Begin");
  // Send the sketch version information to the gateway and Controller
  gw.sendSketchInfo("Pressure Sensor", "1.0");
  Serial.println("Sketch data Presented");
  delay(1000);
  BaroSensor.begin();
  Serial.println("Brometer Sensor started...");
  delay(1000);
  // Register sensors to gw (they will be created as child devices)
  gw.present(BARO_CHILD, S_BARO);
  Serial.println("presenting Barometer");
  delay(1000);
  gw.present(TEMP_CHILD, S_TEMP);
  Serial.println("presenting Thermometer");
  delay(1000);
  metric =  gw.getConfig().isMetric;
  Serial.println("requesting Metric");
  delay(1000);
  Serial.println("Setup Complete");
}

void loop() 
{
}

[Myles L]

The Sensor and Ethernet gateway both have 4.7uf electrolytic capacitors across the power input of the radio's (I cant get much distance out of them, maybe <10 metres, but they do work for the relay sensor).

The serial output looks like this: ��Ah���Y5����������i��`q!���J�����

[Myles L]

Using that sketch I was able to add it to Vera, it just does not report pressure or forecast (obviously as there is no data being presented to it)

[BulldogLowell]

Great, now just plug the loop() back into the sketch, flash your arduino, and you should be good to go

oh... and add a Serial.begin(yourDesiredBaudRate) to setup() ;)

[Myles L]

Ok, so close! Adding back the rest I get and endless string of � in the serial monitor and nothing adds to Vera.

I don't actually need the temp (tried commenting it out but could not get it to compile) if that makes it easier?

Here is what I have:

#include <SPI.h>
#include <MySensor.h>
#include <Wire.h>
#include <BaroSensor.h>

#define BARO_CHILD 0
#define TEMP_CHILD 1
#define DEVICE_ID 99

unsigned long SLEEP_TIME = 60000; // Sleep time between reads (in seconds)

MySensor gw;

float lastPressure = -1;
float lastTemp = -1;
int lastForecast = -1;
const char *weather[] = {"stable","sunny","cloudy","unstable","thunderstorm","unknown"};
int minutes;
float pressureSamples[180];
int minuteCount = 0;
bool firstRound = true;
float pressureAvg[7];
float dP_dt;
boolean metric;
MyMessage tempMsg(TEMP_CHILD, V_TEMP);
MyMessage pressureMsg(BARO_CHILD, V_PRESSURE);
MyMessage forecastMsg(BARO_CHILD, V_FORECAST);

void setup()
{
Serial.begin(9600);
gw.begin(NULL, DEVICE_ID, false);
delay(1000);
Serial.println("Got to GW.Begin");
// Send the sketch version information to the gateway and Controller
gw.sendSketchInfo("Pressure Sensor", "1.0");
Serial.println("Sketch data Presented");
delay(1000);
BaroSensor.begin();
Serial.println("Brometer Sensor started...");
delay(1000);
// Register sensors to gw (they will be created as child devices)
gw.present(BARO_CHILD, S_BARO);
Serial.println("presenting Barometer");
delay(1000);
gw.present(TEMP_CHILD, S_TEMP);
Serial.println("presenting Thermometer");
delay(1000);
metric = gw.getConfig().isMetric;
Serial.println("requesting Metric");
delay(1000);
Serial.println("Setup Complete");
}

void loop()
{
if(!BaroSensor.isOK())
{
Serial.print("Sensor not Found/OK. Error: ");
Serial.println(BaroSensor.getError());
BaroSensor.begin(); // Try to reinitialise the sensor if we can
}

float pressure = BaroSensor.getPressure()/100;
float temperature = BaroSensor.getTemperature();
if (!metric)
{
// Convert to fahrenheit
temperature = temperature * 9.0 / 5.0 + 32.0;
}

int forecast = sample(pressure);

Serial.print("Temperature = ");
Serial.print(temperature);
Serial.println(metric?" C":" F");
Serial.print("Pressure = ");
Serial.print(pressure);
Serial.println(" Pa");
Serial.println(weather[forecast]);

if (temperature != lastTemp) {
gw.send(tempMsg.set(temperature,1));
lastTemp = temperature;
}

if (pressure != lastPressure) {
gw.send(pressureMsg.set(pressure, 0));
lastPressure = pressure;
}

if (forecast != lastForecast)
{
gw.send(forecastMsg.set(weather[forecast]));
lastForecast = forecast;
}

/*
DP/Dt explanation

0 = "Stable Weather Pattern"
1 = "Slowly rising Good Weather", "Clear/Sunny "
2 = "Slowly falling L-Pressure ", "Cloudy/Rain "
3 = "Quickly rising H-Press", "Not Stable"
4 = "Quickly falling L-Press", "Thunderstorm"
5 = "Unknown (More Time needed)
*/

gw.sleep(SLEEP_TIME);
}

int sample(float pressure) {
// Algorithm found here
// http://www.freescale.com/files/sensors/doc/app_note/AN3914.pdf
if (minuteCount > 180)
minuteCount = 6;
pressureSamples[minuteCount] = pressure;
minuteCount++;

if (minuteCount == 5) {
// Avg pressure in first 5 min, value averaged from 0 to 5 min.
pressureAvg[0] = ((pressureSamples[1] + pressureSamples[2]
+ pressureSamples[3] + pressureSamples[4] + pressureSamples[5])
/ 5);
} else if (minuteCount == 35) {
// Avg pressure in 30 min, value averaged from 0 to 5 min.
pressureAvg[1] = ((pressureSamples[30] + pressureSamples[31]
+ pressureSamples[32] + pressureSamples[33]
+ pressureSamples[34]) / 5);
float change = (pressureAvg[1] - pressureAvg[0]);
if (firstRound) // first time initial 3 hour
dP_dt = ((65.0 / 1023.0) * 2 * change); // note this is for t = 0.5hour
else
dP_dt = (((65.0 / 1023.0) * change) / 1.5); // divide by 1.5 as this is the difference in time from 0 value.
} else if (minuteCount == 60) {
// Avg pressure at end of the hour, value averaged from 0 to 5 min.
pressureAvg[2] = ((pressureSamples[55] + pressureSamples[56]
+ pressureSamples[57] + pressureSamples[58]
+ pressureSamples[59]) / 5);
float change = (pressureAvg[2] - pressureAvg[0]);
if (firstRound) //first time initial 3 hour
dP_dt = ((65.0 / 1023.0) * change); //note this is for t = 1 hour
else
dP_dt = (((65.0 / 1023.0) * change) / 2); //divide by 2 as this is the difference in time from 0 value
} else if (minuteCount == 95) {
// Avg pressure at end of the hour, value averaged from 0 to 5 min.
pressureAvg[3] = ((pressureSamples[90] + pressureSamples[91]
+ pressureSamples[92] + pressureSamples[93]
+ pressureSamples[94]) / 5);
float change = (pressureAvg[3] - pressureAvg[0]);
if (firstRound) // first time initial 3 hour
dP_dt = (((65.0 / 1023.0) * change) / 1.5); // note this is for t = 1.5 hour
else
dP_dt = (((65.0 / 1023.0) * change) / 2.5); // divide by 2.5 as this is the difference in time from 0 value
} else if (minuteCount == 120) {
// Avg pressure at end of the hour, value averaged from 0 to 5 min.
pressureAvg[4] = ((pressureSamples[115] + pressureSamples[116]
+ pressureSamples[117] + pressureSamples[118]
+ pressureSamples[119]) / 5);
float change = (pressureAvg[4] - pressureAvg[0]);
if (firstRound) // first time initial 3 hour
dP_dt = (((65.0 / 1023.0) * change) / 2); // note this is for t = 2 hour
else
dP_dt = (((65.0 / 1023.0) * change) / 3); // divide by 3 as this is the difference in time from 0 value
} else if (minuteCount == 155) {
// Avg pressure at end of the hour, value averaged from 0 to 5 min.
pressureAvg[5] = ((pressureSamples[150] + pressureSamples[151]
+ pressureSamples[152] + pressureSamples[153]
+ pressureSamples[154]) / 5);
float change = (pressureAvg[5] - pressureAvg[0]);
if (firstRound) // first time initial 3 hour
dP_dt = (((65.0 / 1023.0) * change) / 2.5); // note this is for t = 2.5 hour
else
dP_dt = (((65.0 / 1023.0) * change) / 3.5); // divide by 3.5 as this is the difference in time from 0 value
} else if (minuteCount == 180) {
// Avg pressure at end of the hour, value averaged from 0 to 5 min.
pressureAvg[6] = ((pressureSamples[175] + pressureSamples[176]
+ pressureSamples[177] + pressureSamples[178]
+ pressureSamples[179]) / 5);
float change = (pressureAvg[6] - pressureAvg[0]);
if (firstRound) // first time initial 3 hour
dP_dt = (((65.0 / 1023.0) * change) / 3); // note this is for t = 3 hour
else
dP_dt = (((65.0 / 1023.0) * change) / 4); // divide by 4 as this is the difference in time from 0 value
pressureAvg[0] = pressureAvg[5]; // Equating the pressure at 0 to the pressure at 2 hour after 3 hours have past.
firstRound = false; // flag to let you know that this is on the past 3 hour mark. Initialized to 0 outside main loop.
}

if (minuteCount < 35 && firstRound) //if time is less than 35 min on the first 3 hour interval.
return 5; // Unknown, more time needed
else if (dP_dt < (-0.25))
return 4; // Quickly falling LP, Thunderstorm, not stable
else if (dP_dt > 0.25)
return 3; // Quickly rising HP, not stable weather
else if ((dP_dt > (-0.25)) && (dP_dt < (-0.05)))
return 2; // Slowly falling Low Pressure System, stable rainy weather
else if ((dP_dt > 0.05) && (dP_dt < 0.25))
return 1; // Slowly rising HP stable good weather
else if ((dP_dt > (-0.05)) && (dP_dt < 0.05))
return 0; // Stable weather
else
return 5; // Unknown
}