Merge pull request #27 from shramik49/master

Add HC-SR04 code

Author: jburhenn

examples/CommunitySubmitted/DHT/DHT.ino

@@ -9,7 +9,7 @@
   3. Attach a DHT to your Arduino:
    Schematic:
    DHT    Arduino
-   [VDD] --- [3V3]
+   [VDD] --- [5V]
    [GND] --- [GND]
    [OUTPUT] --- [Digital Pin 2]
   4. Set the TEMPERATURE_VIRTUAL_CHANNEL value below to a free virtual channel.

examples/CommunitySubmitted/HC-SR04/HC-SR04.ino

@@ -0,0 +1,66 @@
+/*
+  Cayenne HC-SR04 Example
+  This sketch shows how to send HC-SR04 Sensor data to the Cayenne Dashboard.
+  The CayenneMQTT Library is required to run this sketch. If you have not already done so you can install it from the Arduino IDE Library Manager.
+  Steps:
+  1. Attach a HC-SR04 to your Arduino:
+   Schematic:
+   HC-SR04    Arduino
+   [VCC] --- [5V]
+   [GND] --- [GND]
+   [TRIGGER_PIN] --- [Digital Pin 2]
+   [ECHO_PIN] --- [Digital Pin 3]
+  2. Set the DISTANCE_VIRTUAL_CHANNEL value below to a free virtual channel.
+  3. Set the Cayenne authentication info to match the authentication info from the Dashboard.
+  4. Compile and upload this sketch.
+  5. Once the Arduino connects to the Dashboard it should automatically create temporary display widget with data.
+   To make a temporary widget permanent click the plus sign on the widget.
+*/
+
+#define CAYENNE_DEBUG
+#define CAYENNE_PRINT Serial // Comment this out to disable prints and save space
+#include <CayenneMQTTEthernet.h>
+
+// Cayenne authentication info. This should be obtained from the Cayenne Dashboard.
+char username[] = "MQTT_USERNAME";
+char password[] = "MQTT_PASSWORD";
+char clientID[] = "CLIENT_ID";
+
+#define DISTANCE_VIRTUAL_CHANNEL 1
+
+// Defines pins numbers for the HC-SR04 connections.
+#define TRIGGER_PIN  2
+#define ECHO_PIN 3
+
+// Defines variables for storing the calculated values.
+long duration;
+int distance;
+
+void setup() {
+  pinMode(TRIGGER_PIN, OUTPUT);
+  pinMode(ECHO_PIN, INPUT);
+  Serial.begin(9600);
+  Cayenne.begin(username, password, clientID);
+}
+
+void loop() {
+  Cayenne.loop();
+}
+
+// This function is called at intervals to send HC-SR04 sensor data to Cayenne.
+CAYENNE_OUT(DISTANCE_VIRTUAL_CHANNEL)
+{
+  digitalWrite(TRIGGER_PIN, LOW); // Clears the trigger pin
+  delayMicroseconds(2);
+
+  digitalWrite(TRIGGER_PIN, HIGH); // Sets the trigger pin on HIGH state for 10 micro seconds
+  delayMicroseconds(10);
+  digitalWrite(TRIGGER_PIN, LOW);
+
+  duration = pulseIn(ECHO_PIN, HIGH); // Reads the echo pin, returns the sound wave travel time in microseconds
+
+  distance = duration * 0.034 / 2; // Calculating the distance.
+
+  // Send the distance value to Cayenne on proximity widget in centimeter.
+  Cayenne.virtualWrite(DISTANCE_VIRTUAL_CHANNEL, distance, "prox", "cm");
+}