Implement I2C support into firmware

envisens/atmega_fw/atmega_fw.ino

@@ -20,6 +20,10 @@ DHT dht(DHT_PIN, DHT_TYPE);
 
 int sensorValue;
 long last_sample = 0;
+float hmid = 0; // humidity
+float temp = 0; // temperature
+float heat = 0; // heat index
+float airq = 0; // air quality / gas 
  
 void setup() {
   Serial.begin(SERIAL_BAUDRATE); 
@@ -27,6 +31,12 @@ void setup() {
   pinMode(LED_BUILTIN, OUTPUT); 
   digitalWrite(LED_BUILTIN, LOW);
   dht.begin();
+  Wire.begin(8);                // join i2c bus with address #8
+  Wire.onRequest(requestEvent); // register event
+}
+
+void requestEvent() {
+  Wire.write("he1234");
 }
 
 void loop() {
@@ -38,25 +48,25 @@ void loop() {
     last_sample = now;
     if (OPERATION_BLINK_EN) {digitalWrite(LED_BUILTIN, HIGH);}
 
-    float h = dht.readHumidity();
-    float t = dht.readTemperature();
+    hmid = dht.readHumidity();
+    temp = dht.readTemperature();
   
-    if (isnan(h) || isnan(t)) {
+    if (isnan(hmid) || isnan(temp)) {
       Serial.println(F("Failed to read from DHT sensor!"));
     } else {
-      float hi = dht.computeHeatIndex(t, h, false);
+      heat = dht.computeHeatIndex(temp, hmid, false);
       Serial.print(F("Humidity: "));
-      Serial.print(h);
+      Serial.print(hmid);
       Serial.print(F("%  Temperature: "));
-      Serial.print(t);
+      Serial.print(temp);
       Serial.print(F("°C  Heat index: "));
-      Serial.print(hi);
-      Serial.println(F("°C "));
+      Serial.print(heat);
+      Serial.print(F("°C "));
     }
     
-    sensorValue = analogRead(MQ135_PIN); 
-    Serial.print("AirQuality=");
-    Serial.print(sensorValue, DEC);
+    airq = analogRead(MQ135_PIN); 
+    Serial.print("AirQuality: ");
+    Serial.print(airq);
     Serial.println(" PPM");
   }
 }