Added led for signalling change

src/main.cpp

@@ -7,10 +7,19 @@
 #include <ESP8266WebServer.h>
 #include <WiFiManager.h>  
 #include <ArduinoJson.h>
+#include <NewPing.h>
 
 #define TURN_ON LOW
 #define TURN_OFF HIGH
 
+const int trigPin = D1;  //D6
+const int echoPin = D2;  //D5
+const int ledPin  = LED_BUILTIN;  //D1
+const float maxDistance = 4.0;
+const float minimumChange = 0.2;
+const int updateInterval_ms = 1; // s
+const int ledInterval_ms = 5; // s
+
 struct Config {
   IPAddress mqtt_server = {192, 168, 249, 5};
   uint16 mqtt_port = 1883;
@@ -18,8 +27,10 @@ struct Config {
 
 MQTTHelper mqtt;
 
-#define heartbeatMillis 10000
-#define messageMillis 1000
+NewPing sonar(trigPin,echoPin,maxDistance*100.0);
+
+#define heartbeatMillis 5000
+#define messageMillis 5000
 
 //flag for saving data
 bool shouldSaveConfig = false;
@@ -29,19 +40,21 @@ void saveConfigCallback () {
   shouldSaveConfig = true;
 }
 
-void heartbeat(int times = 3);
-void longbeat();
+void signal_led(bool ons = true);
+void heartbeat_led(int times = 2);
+void longbeat_led();
 void setup_wifi(String ssid, String password);
 void reconnect();
 void readConfig();
 void saveConfig();
+float readDistance();
 
 void setup() {
   Serial.begin(115200);
   Serial.println();
   randomSeed(analogRead(0));
-  pinMode(LED_BUILTIN, OUTPUT);
-  pinMode(LED_BUILTIN, TURN_OFF);
+  pinMode(ledPin, OUTPUT);
+  digitalWrite(ledPin, TURN_OFF);
 
   //clean FS, for testing
   //SPIFFS.format();
@@ -70,12 +83,16 @@ void setup() {
 
 long lastMessage = 0;
 long lastHeartbeat = 0;
-float distance = 0.0;
+float oldDistance = 0.0;
 float diff = 4.0;
 
-bool checkBound(float newValue, float prevValue, float maxDiff) {
-  return !isnan(newValue) &&
-         (newValue < prevValue + maxDiff || newValue > prevValue - maxDiff);
+bool checkBounds(float value, float min, float max) {
+  return !isnan(value) &&
+         (value >= min &&  value <= max);
+}
+
+bool signalChange(float distance, float oldDistance) {
+  return fabs(distance - oldDistance) > minimumChange;
 }
 
 void loop() {
@@ -84,26 +101,57 @@ void loop() {
   long now = millis();
   if (now - lastHeartbeat > heartbeatMillis) {
     lastHeartbeat = now;
-    heartbeat();
+    heartbeat_led();
   }
 
   if (now - lastMessage > messageMillis) {
     lastMessage = now;
 
-    float newDistance = random(5,400)/100.0;
-    // Serial.print("New distance:");
-    // Serial.println(String(newDistance).c_str());
+    float distance = readDistance();
+    //float distance = random(5,400)/100.0;
+    // Serial.print("Distance read:");
+    // Serial.print(int(distance*1000));
+    // Serial.println(" mm");
 
-    if (checkBound(newDistance, distance, diff)) {
-      distance = newDistance;
-      auto sensorName = "distance";
-      Serial.print(mqtt.getTopic(sensorName));
-      Serial.println(" = "+String(distance));
-      mqtt.publish("distance", distance);
+    if (checkBounds(distance, 0, maxDistance)) {
+      String node = "distance";
+      Serial.println(mqtt.getTopic(node)+" = "+String(distance));
+      mqtt.publish(node, distance);
+
+      bool signal = signalChange(distance, oldDistance);
+      node = "signal";
+      Serial.println(mqtt.getTopic(node)+" = "+String(signal));
+      mqtt.publish(node, signal);
+      if (signal)
+        signal_led();
     }
+
+    oldDistance = distance;
   }
 }
 
+float getEchoTime() {
+    // Clears the trigPin
+  digitalWrite(trigPin, LOW);
+  delayMicroseconds(2);
+
+  // Sets the trigPin on HIGH state for 10 micro seconds
+  digitalWrite(trigPin, HIGH);
+  delayMicroseconds(10);
+  digitalWrite(trigPin, LOW);
+
+  // Reads the echoPin, returns the sound wave travel time in microseconds
+  return pulseIn(echoPin, HIGH);
+}
+
+float readDistance() {
+  //auto ping_us = getEchoTime();
+  auto ping_us = sonar.ping();
+  // Calculating the distance @ 10 °C from d = t_ping /2 * c => t_ping /2 * 337 [m/s] => t_ping_us / 1e-6 * 1/2 * 337 
+  auto computedDistance = ping_us*0.0001685;
+  return computedDistance;
+}
+
 void readConfig() {
   //read configuration from FS json
   Serial.println("mounting FS...");
@@ -158,20 +206,29 @@ void saveConfig() {
   }
 }
 
-void heartbeat(int times) 
+
+void signal_led(bool on) 
+{
+  if (on)
+    digitalWrite(ledPin, TURN_ON);
+  else
+    digitalWrite(ledPin, TURN_OFF); 
+}
+
+void heartbeat_led(int times) 
 {
   for (int blink=0; blink<times; blink++)
   {
-    digitalWrite(LED_BUILTIN, TURN_ON);
-    delay(20);
-    digitalWrite(LED_BUILTIN, TURN_OFF);
+    signal_led(true);
+    delay(10);
+    signal_led(false);
     delay(200);
   }
 }
 
-void longbeat() 
+void longbeat_led() 
 {
-  digitalWrite(LED_BUILTIN, TURN_ON);
+  signal_led(true);
   delay(500);
-  digitalWrite(LED_BUILTIN, TURN_OFF);
+  signal_led(false);
 }