X-Git-Url: https://git.rvb.name/weathermon.git/blobdiff_plain/42bd3e809b0fa95d3a463462e242caf40d98bf79..769d0bd71b19b467c195838379a379e0e2d69c2b:/Weather_Station.ino

diff --git a/Weather_Station.ino b/Weather_Station.ino
index 8ba7cee..9358d3d 100644
--- a/Weather_Station.ino
+++ b/Weather_Station.ino
@@ -71,6 +71,8 @@ SFE_BMP180 pressure;
 
 // DHT object for humidity sensor
 DHT dht;
+
+#define CO2_PIN A1
 #define DHT_PIN 4
 #define GAS_PIN A0
 #define START_DELAY 20000
@@ -78,6 +80,48 @@ DHT dht;
 
 byte HasBaro;
 
+#define READ_SAMPLE_INTERVAL 50
+#define READ_SAMPLE_TIMES 5
+
+#define MQ135_RES 1000
+
+float MQRead(int mq_pin)
+{
+
+  int i;
+  float rs=0;
+  float rr;
+
+  for (i=0;i<READ_SAMPLE_TIMES;i++) {
+    rr = analogRead(mq_pin);
+    rs += rr;
+    delay(READ_SAMPLE_INTERVAL);
+  }
+ 
+  rs = rs/READ_SAMPLE_TIMES;
+  return rs;
+
+}
+
+/// Parameters to model temperature and humidity dependence
+
+#define CORA 0.00035
+#define CORB 0.02718
+#define CORC 1.39538
+#define CORD 0.0018
+
+float getMQ135CorrectionFactor(float t, float h) {
+  return CORA * t * t - CORB * t + CORC - (h-33.)*CORD;
+}
+
+#define RZERO 25300
+#define PARA 116.6020682
+#define PARB 2.769034857
+
+float getMQ135ppm(float Resistance) {
+  return PARA * pow((Resistance/RZERO), -PARB);  
+}
+
 void setup()
 {
   delay(START_DELAY);
@@ -97,6 +141,11 @@ void setup()
   
   dht.setup(DHT_PIN);
   
+  pinMode(GAS_PIN,INPUT);
+  pinMode(CO2_PIN,INPUT);
+  
+  digitalWrite(GAS_PIN, LOW);
+  digitalWrite(CO2_PIN, LOW);
 }
 
 void loop()
@@ -185,13 +234,39 @@ void loop()
     Serial1.print(",HUMIDITY=");
     Serial1.println(DHT_H);
   } else {
-    Serial1.println("ERROR:TYPE=DHT22,MESSAGE=MEASURING ERROR\n");
+    Serial1.print("ERROR:TYPE=DHT22,MESSAGE=");
+    Serial1.println(dht.getStatusString());
   }
   
-  Gas = analogRead(GAS_PIN);
+  Gas = MQRead(GAS_PIN);
   
   Serial1.print("SENSOR:TYPE=MQ4,VALUE=");
   Serial1.println(Gas);
+
+  float MQ135_Resistance;
+  float CO2_raw;
+  float CO2_ppm;
+
+  float CO2_resistance;
+
+  CO2_raw = MQRead(CO2_PIN);
+  Serial1.print("DEBUG:RAW=");
+  Serial1.println(CO2_raw);
+
+  MQ135_Resistance=MQ135_RES*(1023./CO2_raw-1);
+  
+  Serial1.print("DEBUG:RESISTANCE=");
+  Serial1.println(MQ135_Resistance);
+  
+  MQ135_Resistance=MQ135_Resistance/getMQ135CorrectionFactor(DHT_T,DHT_H);
+  Serial1.print("DEBUG:CORR_RESISTANCE=");
+  Serial1.println(MQ135_Resistance);  
+
+  CO2_ppm = getMQ135ppm(MQ135_Resistance);  
+  
+  Serial1.print("SENSOR:TYPE=MQ135,VALUE=");
+  Serial1.println(CO2_ppm);
   
   delay(DELAY);  // Pause for 50 seconds.
 }
+