add error output on dropped packets, and mqtt w/callbacks example

Adafruit_MQTT.cpp

@@ -242,6 +242,8 @@ uint16_t Adafruit_MQTT::processPacketsUntil(uint8_t *buffer, uint8_t waitforpack
     if ((buffer[0] >> 4) == waitforpackettype) {
       //DEBUG_PRINTLN(F("Found right packet")); 
       return len;
+    } else {
+      ERROR_PRINTLN(F("Dropped a packet"));
     }
   }
   return 0;

Adafruit_MQTT.h

@@ -49,6 +49,16 @@
   #define DEBUG_PRINTBUFFER(buffer, len) {}
 #endif
 
+#ifdef MQTT_ERROR
+  #define ERROR_PRINT(...) { DEBUG_PRINTER.print(__VA_ARGS__); }
+  #define ERROR_PRINTLN(...) { DEBUG_PRINTER.println(__VA_ARGS__); }
+  #define ERROR_PRINTBUFFER(buffer, len) { printBuffer(buffer, len); }
+#else
+  #define ERROR_PRINT(...) {}
+  #define ERROR_PRINTLN(...) {}
+  #define ERROR_PRINTBUFFER(buffer, len) {}
+#endif
+
 // Use 3 (MQTT 3.0) or 4 (MQTT 3.1.1)
 #define MQTT_PROTOCOL_LEVEL 4
 

examples/mqtt_esp8266_callback/mqtt_esp8266_callback.ino

@@ -0,0 +1,147 @@
+/***************************************************
+  Adafruit MQTT Library ESP8266 Example
+
+  Must use ESP8266 Arduino from:
+    https://github.com/esp8266/Arduino
+
+  Works great with Adafruit's Huzzah ESP board:
+  ----> https://www.adafruit.com/product/2471
+
+  Adafruit invests time and resources providing this open source code,
+  please support Adafruit and open-source hardware by purchasing
+  products from Adafruit!
+
+  Written by Tony DiCola for Adafruit Industries.
+  MIT license, all text above must be included in any redistribution
+ ****************************************************/
+#include <ESP8266WiFi.h>
+#include "Adafruit_MQTT.h"
+#include "Adafruit_MQTT_Client.h"
+
+/************************* WiFi Access Point *********************************/
+
+#define WLAN_SSID       "network"
+#define WLAN_PASS       "password"
+
+/************************* Adafruit.io Setup *********************************/
+
+#define AIO_SERVER      "io.adafruit.com"
+#define AIO_SERVERPORT  1883
+#define AIO_USERNAME    "user"
+#define AIO_KEY         "key"
+
+/************ Global State (you don't need to change this!) ******************/
+
+// Create an ESP8266 WiFiClient class to connect to the MQTT server.
+WiFiClient client;
+
+// Setup the MQTT client class by passing in the WiFi client and MQTT server and login details.
+Adafruit_MQTT_Client mqtt(&client, AIO_SERVER, AIO_SERVERPORT, AIO_USERNAME, AIO_USERNAME, AIO_KEY);
+
+/****************************** Feeds ***************************************/
+
+// Setup a feed called 'time' for subscribing to current time
+Adafruit_MQTT_Subscribe timefeed = Adafruit_MQTT_Subscribe(&mqtt, "time/seconds");
+
+// Setup a feed called 'slider' for subscribing to changes on the slider
+Adafruit_MQTT_Subscribe slider = Adafruit_MQTT_Subscribe(&mqtt, AIO_USERNAME "/feeds/slider", MQTT_QOS_1);
+
+// Setup a feed called 'onoff' for subscribing to changes to the button
+Adafruit_MQTT_Subscribe onoffbutton = Adafruit_MQTT_Subscribe(&mqtt, AIO_USERNAME "/feeds/onoff", MQTT_QOS_1);
+
+/*************************** Sketch Code ************************************/
+
+void timecallback(uint32_t x) {
+  Serial.print("Hey we're in a time callback, the epoch time is: ");
+  Serial.println(x);
+}
+
+void slidercallback(double x) {
+  Serial.print("Hey we're in a slider callback, the slider value is: ");
+  Serial.println(x);
+}
+
+void onoffcallback(char *data, uint16_t len) {
+  Serial.print("Hey we're in a onoff callback, the button value is: ");
+  Serial.println(data);
+}
+
+
+void setup() {
+  Serial.begin(115200);
+  delay(10);
+
+  Serial.println(F("Adafruit MQTT demo"));
+
+  // Connect to WiFi access point.
+  Serial.println(); Serial.println();
+  Serial.print("Connecting to ");
+  Serial.println(WLAN_SSID);
+
+  WiFi.begin(WLAN_SSID, WLAN_PASS);
+  while (WiFi.status() != WL_CONNECTED) {
+    delay(500);
+    Serial.print(".");
+  }
+  Serial.println();
+
+  Serial.println("WiFi connected");
+  Serial.println("IP address: "); Serial.println(WiFi.localIP());
+
+  timefeed.setCallback(timecallback);
+  slider.setCallback(slidercallback);
+  onoffbutton.setCallback(onoffcallback);
+  
+  // Setup MQTT subscription for time feed.
+  mqtt.subscribe(&timefeed);
+  mqtt.subscribe(&slider);
+  mqtt.subscribe(&onoffbutton);
+
+}
+
+uint32_t x=0;
+
+void loop() {
+  // Ensure the connection to the MQTT server is alive (this will make the first
+  // connection and automatically reconnect when disconnected).  See the MQTT_connect
+  // function definition further below.
+  MQTT_connect();
+
+  // this is our 'wait for incoming subscription packets and callback em' busy subloop
+  // try to spend your time here:
+  mqtt.processPackets(10000);
+  
+  // ping the server to keep the mqtt connection alive
+  // NOT required if you are publishing once every KEEPALIVE seconds
+  
+  if(! mqtt.ping()) {
+    mqtt.disconnect();
+  }
+}
+
+// Function to connect and reconnect as necessary to the MQTT server.
+// Should be called in the loop function and it will take care if connecting.
+void MQTT_connect() {
+  int8_t ret;
+
+  // Stop if already connected.
+  if (mqtt.connected()) {
+    return;
+  }
+
+  Serial.print("Connecting to MQTT... ");
+
+  uint8_t retries = 3;
+  while ((ret = mqtt.connect()) != 0) { // connect will return 0 for connected
+       Serial.println(mqtt.connectErrorString(ret));
+       Serial.println("Retrying MQTT connection in 10 seconds...");
+       mqtt.disconnect();
+       delay(10000);  // wait 10 seconds
+       retries--;
+       if (retries == 0) {
+         // basically die and wait for WDT to reset me
+         while (1);
+       }
+  }
+  Serial.println("MQTT Connected!");
+}