ESP8266 - Added MQTT subscribe example

examples/ESP8266_MQTT_Subscribe/ESP8266_MQTT_Subscribe.ino

@@ -0,0 +1,70 @@
+/*
+ * KiteLib ESP8266 MQTT Publish Example
+ * 
+ * This example publishes MQTT messages using ESP8266 WiFi module.
+ * 
+ * The messages are published to https://shiftr.io/try. You can use this namespace
+ * for testing purposes, but remember that it is publicly accessible!
+ * 
+ * IMPORTANT: Before upolading this example, make sure that the ESP8266 module is running
+ * AT firmware (can be found in the /extras folder of the library)!
+ */
+
+// include the library
+#include <KiteLib.h>
+
+// ESP8266 module is in slot A on the shield
+ESP8266 wifi = Kite.ModuleA;
+
+void setup() {
+  Serial.begin(9600);
+
+  // initialize ESP8266 with baudrate 9600
+  Serial.print(F("[ESP8266] Initializing ... "));
+  byte state = wifi.begin(9600);
+  if(state == ERR_NONE) {
+    Serial.println(F("success!"));
+  } else {
+    Serial.print(F("failed, code 0x"));
+    Serial.println(state, HEX);
+    while(true);
+  }
+
+  // join AP named "SSID" using the password "password"
+  Serial.print(F("[ESP8266] Joining AP ... "));
+  state = wifi.join("SSID", "password");
+  if(state == ERR_NONE) {
+    Serial.println(F("success!"));
+  } else {
+    Serial.print(F("failed, code 0x"));
+    Serial.println(state, HEX);
+    while(true);
+  }
+
+  // connect to MQTT broker using client ID "arduino", username "try" and password "try"
+  Serial.print(F("[ESP8266] Connecting to MQTT broker ... "));
+  state = wifi.MqttConnect("broker.shiftr.io", "arduino", "try", "try");
+  if(state == ERR_NONE) {
+    Serial.println(F("success!"));
+  } else {
+    Serial.print(F("failed, code 0x"));
+    Serial.println(state, HEX);
+    while(true);
+  }
+}
+
+void loop() {
+  // publish MQTT message to the topic "hello" with content "world"
+  Serial.print(F("[ESP8266] Publishing MQTT message ... "));
+  byte state = wifi.MqttPublish("hello", "world");
+  if(state == ERR_NONE) {
+    Serial.println(F("success!"));
+  } else {
+    Serial.print(F("failed, code 0x"));
+    Serial.println(state, HEX);
+  }
+
+  // wait for a second before publishing again
+  delay(1000);
+}
+