Implement Sensor struct for better data handling and force publication

espsens/espsens.ino

@@ -17,22 +17,27 @@
 #define TOPIC_BASE "sensor/" SENSOR_ID "/"
 #define TOPIC_TEMP TOPIC_BASE "temperature"
 #define TOPIC_HMID TOPIC_BASE "humidity"
-#define TOPIC_HEAT TOPIC_BASE "heat_index"
 #define TOPIC_ABHU TOPIC_BASE "abs_humidity"
+#define TOPIC_HEAT TOPIC_BASE "heat_index"
 
 #define DIFF_TEMP 0.3 // sensor has only 0.5°C accuracy, triggering on less is ludicrous
 #define DIFF_HMID 1.5 // humidity doesn't change that much anyways
-#define DIFF_HEAT 0.3 // this one's actually quite active
 #define DIFF_ABHU 0.2 // small changes mean quite something
+#define DIFF_HEAT 0.3 // this one's actually quite active
 
-float hmid = 0; // humidity
-float hmid_r = 0; // humidity
-float abhu = 0; // absolute humidity
-float abhu_r = 0; // absolute humidity
-float temp = 0; // temperature
-float temp_r = 0; // temperature
-float heat = 0; // heat index
-float heat_r = 0; // heat index
+struct Sensor {
+  String desc; // sensor description
+  char* topic; // sensor topic
+  float diff; // value difference for an update
+  float value; // current values
+  float lastValue; // value at last update
+  int lastUpdate; // number of samples since last update
+};
+
+Sensor temp = {"temperature (°C)", TOPIC_TEMP, DIFF_TEMP, 0.0, 0.0, -1}; // temperature
+Sensor hmid = {"humidity (%)", TOPIC_HMID, DIFF_HMID, 0.0, 0.0, -1}; // humidity
+Sensor abhu = {"absolute humidity (gr/m³)", TOPIC_ABHU, DIFF_ABHU, 0.0, 0.0, -1}; // absolute humidity
+Sensor heat = {"heat index (°C)", TOPIC_HEAT, DIFF_HEAT, 0.0, 0.0, -1}; // heat index
 
 #define DHTPIN 4     // Digital pin connected to the DHT sensor
 #define DHTTYPE DHT22   // DHT 22  (AM2302), AM2321
@@ -106,26 +111,37 @@ bool checkPlausibility(float newValue, float prevValue, float maxDiff) {
 }
 
 long lastMsg = 0;
-long lastSent = 0; 
-bool published = false;
-bool forcePublish = false;
 
-bool publish (String desc, char *topic, float val, float &lastVal, float diff, bool force){
-  bool ret = false;
-  Serial.println("Sample " + desc + ": " + String(val).c_str());
-  if (checkVariation(val, lastVal, diff) or force) {
-    Serial.println("Sufficient variation on " + desc + ": " + String(val).c_str());
-    if (checkPlausibility(val, lastVal, diff) or force) {
-      Serial.println("Value published");
-      client.publish(topic, String(val).c_str(), true);
-      ret = true;
-    } else {
-      Serial.print("** ERROR: Value out of bounds, not published. Last value :");
-      Serial.println(String(lastVal).c_str());
-    }
-    lastVal = val;
+void publish (Sensor &sensor){
+  bool force = false;
+  Serial.println("Sample " + sensor.desc + ": " + String(sensor.value).c_str());
+
+  // check if first sample, set lastValue and return
+  if (sensor.lastUpdate == -1){ 
+    sensor.lastValue = sensor.value;
+    return;
+  }
+
+  // force an update if the number of samples without update is exceeded
+  Serial.println(" * Forcing publication if sensor value is plausible");
+  force = sensor.lastUpdate >= FORCE_PERIOD;
+
+  // update the sample counter, will be reset if sample is published
+  sensor.lastUpdate += 1;
+
+  // check if there was sufficient variation on the signal and if the value is plausible
+  if (checkVariation(sensor.value, sensor.lastValue, sensor.diff) or force) {
+    Serial.println(" Sufficient variation on " + sensor.desc + ": " + String(sensor.value).c_str());
+    if (checkPlausibility(sensor.value, sensor.lastValue, sensor.diff)) {
+      Serial.println(" Value published");
+      client.publish(sensor.topic, String(sensor.value).c_str(), true);
+      sensor.lastUpdate = 0;
+    } else {
+      Serial.print(" ** ERROR: Value out of bounds, not published. Last value :");
+      Serial.println(String(sensor.lastValue).c_str());
+    }
+    sensor.lastValue = sensor.value;
   }
-  return ret;
 }
 
 void loop() {
@@ -143,32 +159,18 @@ void loop() {
     lastMsg = now;
     if (OPERATION_BLINK_EN) {digitalWrite(LED_BUILTIN, HIGH);}
 
-    hmid = dht.readHumidity();
-    temp = dht.readTemperature();
+    hmid.value = dht.readHumidity();
+    temp.value = dht.readTemperature();
   
-    if (!isnan(hmid) && !isnan(temp)){
-      abhu = (6.112 * ( pow(2.71828, ((17.67 * temp) / (temp + 243.5))) * hmid * 2.1674)) / (273.15 + temp);
-      heat = dht.computeHeatIndex(temp, hmid, false);
-    }
- 
-    published = false;
-    if (lastSent > FORCE_PERIOD) {
-      Serial.println(F("Forcing a publish of all values"));
-      forcePublish = true;
-      lastSent = 0;
+    if (!isnan(hmid.value) && !isnan(temp.value)){
+      abhu.value = (6.112 * ( pow(2.71828, ((17.67 * temp.value) / (temp.value + 243.5))) * hmid.value * 2.1674)) / (273.15 + temp.value);
+      heat.value = dht.computeHeatIndex(temp.value, hmid.value, false);
     }
 
-    published += publish("temperature", TOPIC_TEMP, temp, temp_r, DIFF_TEMP, forcePublish);
-    published += publish("humidity", TOPIC_HMID, hmid, hmid_r, DIFF_HMID, forcePublish);
-    published += publish("heat index", TOPIC_HEAT, heat, heat_r, DIFF_HEAT, forcePublish);
-    published += publish("absolute humidity", TOPIC_ABHU, abhu, abhu_r, DIFF_ABHU, forcePublish);    
-    
-    if (published == false) {
-      lastSent = lastSent + 1;
-    } else {
-      lastSent = 0;
-    }
-    
-    forcePublish = false;
+    publish(temp);
+    publish(hmid);
+    publish(heat);
+    publish(abhu);    
+   
   }
 }