Add support for HC-SR04 sensor (#453)

Adds support for HC-SR04 Ultrasonic distance snsor.

main/ZsensorHCSR04.ino

@@ -0,0 +1,74 @@
+/*  
+  OpenMQTTGateway Addon  - ESP8266 or Arduino program for home automation 
+
+   Act as a wifi or ethernet gateway between your 433mhz/infrared IR signal and a MQTT broker 
+   Send and receiving command by MQTT
+ 
+    HC SR-04 reading Addon
+  
+    Copyright: (c)Florian ROBERT
+    
+    Contributors:
+    - 1technophile
+    - mpember
+  
+    This file is part of OpenMQTTGateway.
+    
+    OpenMQTTGateway is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    OpenMQTTGateway is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+#include "User_config.h"
+
+#ifdef ZsensorHCSR04
+
+unsigned long timeHCSR04 = 0;
+
+void setupHCSR04() {
+  pinMode(HCSR04_TRI_PIN, OUTPUT);    // declare HC SR-04 trigger pin as output
+  pinMode(HCSR04_ECH_PIN, INPUT);     // declare HC SR-04 echo pin as input
+}
+
+void MeasureDistance() {
+  if (millis() > (timeHCSR04 + TimeBetweenReadingHCSR04)) {
+    timeHCSR04 = millis();
+    trc(F("Creating HCSR04 buffer"));
+    StaticJsonBuffer<JSON_MSG_BUFFER> jsonBuffer;
+    JsonObject& HCSR04data = jsonBuffer.createObject();
+    digitalWrite(HCSR04_TRI_PIN, LOW);
+    delayMicroseconds(2);
+    digitalWrite(HCSR04_TRI_PIN, HIGH);
+    delayMicroseconds(10);
+    digitalWrite(HCSR04_TRI_PIN, LOW);
+    unsigned long duration = pulseIn(HCSR04_ECH_PIN, HIGH);
+    if (isnan(duration)) {
+      trc(F("Failed to read from HC SR04 sensor!"));
+    } else {
+      static unsigned int distance = 99999;
+      unsigned int d = duration/58.2;
+      HCSR04data.set("distance", (int)d);
+      if (d > distance) {
+        HCSR04data.set("direction", "away");
+        trc(F("HC SR04 Distance changed"));
+      } else if (d < distance) {
+        HCSR04data.set("direction", "towards");
+        trc(F("HC SR04 Distance changed"));
+      } else if (HCSR04_always) {
+        HCSR04data.set("direction", "static");
+        trc(F("HC SR04 Distance hasn't changed"));
+      }
+      distance = d;
+      if(HCSR04data.size()>0) pub(subjectHCSR04,HCSR04data);
+    }
+  }
+}
+#endif