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    Best posts made by jtm312

    • Mini Weather Station

      This is a new mini weather station that I have been working on.

      It provides Temperature, Humidity, Pressure, and Battery Voltage.

      IMG_0207.JPG

      IMG_0208.JPG

      The case is designed to be printed without the need for any support, has vents in the front and sides. The front slides on to make it easy to replace the 9v battery. It is designed to take a 50x70mm prototype board. This gives heaps of room for the sensors.

      The 3d files can be found on http://www.thingiverse.com/thing:704715

      The code is mostly a refactor from the examples in the MySensors libraries, with a simplification of the forecast algorithm to reduce the amount of memory that it uses.

      #include <SPI.h>
      #include <MySensor.h>  
      #include <DHT.h>  
      #include <Wire.h>
      #include <Adafruit_BMP085.h>
      
      #define CHILD_ID_HUM 0
      #define CHILD_ID_TEMP 1
      #define CHILD_ID_BARO 2
      #define CHILD_ID_BARO_TEMP 3
      
      #define HUMIDITY_SENSOR_DIGITAL_PIN 3
      int BATTERY_SENSE_PIN = A0;  // select the input pin for the battery sense point
      
      #define SLEEP_MINUTE 60000
      #define SLEEP_FIVE_MINUTES 300000
      
      MySensor gw;
      DHT dht;
      Adafruit_BMP085 bmp = Adafruit_BMP085();      // Digital Pressure Sensor 
      
      float   lastTemp = -1.0;
      float   lastHum = -1.0;
      float   lastBaroTemp = -1.0;
      int     lastForecast = -1;
      char    *weather[] = { "Stable", "Sunny", "Cloudy", "Unstable", "Thunderstorm",	"Unknown" };
      int     minutes;
      int     pressureSamples[5];
      float   lastPressureAvg = -1.0;
      int     lastPressure = -1;
      int     minuteCount = 0;
      float   pressureAvg;
      int     pressure;
      float   dP_dt;
      boolean metric = true;
      
      MyMessage msgHum(CHILD_ID_HUM, V_HUM);
      MyMessage msgTemp(CHILD_ID_TEMP, V_TEMP);
      MyMessage msgBaroTemp(CHILD_ID_BARO_TEMP, V_TEMP);
      MyMessage msgBaro(CHILD_ID_BARO, V_PRESSURE);
      MyMessage msgForecast(CHILD_ID_BARO, V_FORECAST);
      
      void setup() {
      	// use the 1.1 V internal reference
      	analogReference(INTERNAL);
      	gw.begin();
      	dht.setup(HUMIDITY_SENSOR_DIGITAL_PIN);
      	if (!bmp.begin()) {
      		Serial.println("Could not find a valid BMP085 sensor, check wiring!");
      	}
      	// Send the Sketch Version Information to the Gateway
      	gw.sendSketchInfo("Mini Weather Station", "3.2");
      
      	// Register all sensors to gw (they will be created as child devices)
      	gw.present(CHILD_ID_HUM, S_HUM);
      	gw.present(CHILD_ID_TEMP, S_TEMP);
      	gw.present(CHILD_ID_BARO, S_BARO);
      	gw.present(CHILD_ID_BARO_TEMP, S_TEMP);
      	metric = gw.getConfig().isMetric;
      }
      
      void loop() {
        
        	Serial.print("minuteCount = ");
      	Serial.println(minuteCount);
      
              // The pressure Sensor Stuff
      	int forecast = SamplePressure();
      
      
              if ( minuteCount > 4 ) { // only every 5 minutes
                      // Process the barometric sensor data 
              	float baro_temperature = bmp.readTemperature();
              	if (!metric) {    // Convert to fahrenheit
              		baro_temperature = baro_temperature * 9.0 / 5.0 + 32.0;
              	}
      
              	if (baro_temperature != lastBaroTemp) {
              		gw.send(msgBaroTemp.set(baro_temperature, 1));
              		lastBaroTemp = baro_temperature;
              	}
      
              	if (pressure != lastPressure) {
              		gw.send(msgBaro.set(pressure, 0));
                              //delay(1000);
      //        		gw.send(msgBaro.set(pressure));
              		lastPressure = pressure;
              	}
      
              	if (forecast != lastForecast) {
              		gw.send(msgForecast.set(weather[forecast]));
              		lastForecast = forecast;
              	}
      
      
                      // The humidity sensor stuff
            	        delay(dht.getMinimumSamplingPeriod());
            
            	        float temperature = dht.getTemperature();
              	if (isnan(temperature)) {
              		Serial.println("Failed reading temperature from DHT");
              	} else if (temperature != lastTemp) {
              		lastTemp = temperature;
            	        	if (!metric) {
            		        	temperature = dht.toFahrenheit(temperature);
            		        }
            		        gw.send(msgTemp.set(temperature, 1));
            		        Serial.print("Temperature: ");
            		        Serial.println(temperature);
            	        }
            
              	float humidity = dht.getHumidity();
              	if (isnan(humidity)) {
              		Serial.println("Failed reading humidity from DHT");
              	} else if (humidity != lastHum) {
              		lastHum = humidity;
              		gw.send(msgHum.set(humidity, 1));
              		Serial.print("Humidity: ");
              		Serial.println(humidity);
              	}
            
            
              	// get the battery Voltage
              	long sensorValue = analogRead(BATTERY_SENSE_PIN);
            
              	// 1M, 100K divider across battery and using internal ADC ref of 1.1V
              	// Sense point is bypassed with 0.1 uF cap to reduce noise at that point
              	// ((1e6+100e3)/100e3)*1.1 = Vmax = 12.1 Volts
              	// 12.1/1023 = Volts per bit = 0.011827957
              	// sensor val at 9v = 9/0.011827957 = 760.909090217
              	// float batteryV  = sensorValue * 0.011827957;
              	long batteryValue = sensorValue * 100L;
              	int batteryPcnt = batteryValue / 761;
              	gw.sendBatteryLevel((batteryPcnt > 100 ? 100 : batteryPcnt)); // this allows for batteries that have slightly over 9v
            
              	Serial.print("Batt %:");
              	Serial.println(batteryPcnt);
              }
      
              if ( minuteCount < 5 )  // sleep a bit
      	        gw.sleep(SLEEP_MINUTE); //while pressure sampling
              else
      	        gw.sleep(SLEEP_FIVE_MINUTES); 
              
      }
      
      int SamplePressure() {
      	// This is a simplification of Algorithm found here to same memory
      	// http://www.freescale.com/files/sensors/doc/app_note/AN3914.pdf
      
      	pressure = bmp.readSealevelPressure(60) / 100; // 60 meters above sealevel
      
      	if (minuteCount > 9) { // we are going to test pressure change every 30 min (5*1min + 5*5min)
      		lastPressureAvg = pressureAvg;
      		minuteCount = 0;
      	}
      
      	if (minuteCount < 5) {
      		pressureSamples[minuteCount] = pressure; // Collect 5 minutes of samples every 30 min
                      Serial.print("  Sample(");
                      Serial.print(minuteCount);
                      Serial.print(") = ");
                      Serial.println(pressure);
              }
      
      	if (minuteCount == 4) { // the 5th minute
      		// Avg pressure in first 5 min, value averaged from 0 to 5 min.
      		pressureAvg = ((pressureSamples[0] + pressureSamples[1]
      				+ pressureSamples[2] + pressureSamples[3] + pressureSamples[4])
      				/ 5);
      		float change = pressureAvg - lastPressureAvg;
      		dP_dt = (((65.0 / 1023.0) * change) / 0.5); // divide by 0.5 as this is the difference in time from last sample 0.5 hours
      		Serial.print("dP_dt = ");
      		Serial.println(dP_dt);
      	}
      
      	minuteCount++;
      
      	if (lastPressureAvg < 0) // no previous pressure sample.
      		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
      
      }
      
      
      posted in My Project
      jtm312
      jtm312
    • RE: Mini Weather Station

      @flopp I have added the FreeCAD file to the Thingiverse post so that people can make any changes they want.

      http://www.thingiverse.com/thing:704715

      posted in My Project
      jtm312
      jtm312
    • RE: Iboard - Cheap Single board Ethernet Arduino with Radio

      @gregl Here is my first attempt at a case for the iBoard. If I get time I will do a re-spin for the smaller radios without aerials.

      http://www.thingiverse.com/thing:474650

      posted in Hardware
      jtm312
      jtm312
    • RE: Mini Weather Station

      @TimO Its been running for about 2 weeks now, and used 5-6% of the battery. I have pulled the leds off of the nano to make it last longer (I was only getting 3 weeks with the leds on). It would be nice to think that I could get 20 weeks. I am also thinking of some more code changes to reduce them amount of power consumed.

      posted in My Project
      jtm312
      jtm312
    • RE: Iboard - Cheap Single board Ethernet Arduino with Radio

      @ServiceXp Just added a new version of the box with LEDs and include button.
      http://www.thingiverse.com/thing:483676

      posted in Hardware
      jtm312
      jtm312
    • RE: Mini Weather Station

      @bjacobse Thanks, they look interesting. I will grab some and have a play.

      posted in My Project
      jtm312
      jtm312