Troubleshooting IO with a very simple publish + subscribe sketch

adafruitio_02_pubsub.ino

// Adafruit IO Publish & Subscribe Example
//
// Adafruit invests time and resources providing this open source code.
// Please support Adafruit and open source hardware by purchasing
// products from Adafruit!
//
// Written by Todd Treece for Adafruit Industries
// Copyright (c) 2016 Adafruit Industries
// Licensed under the MIT license.
//
// All text above must be included in any redistribution.

/************************** Configuration ***********************************/

#include "config.h"

// limit publishing speed
#define IO_LOOP_DELAY 5000
unsigned long lastUpdate = 0;

// set up the 'counter' feed
AdafruitIO_Feed *counter = io.feed("counter");

int count = 0;

void setup() {
  Serial.begin(115200);

  // start connecting, delay until connected
  io.connect();
  counter->onMessage(handleMessage);
  while(io.status() < AIO_CONNECTED) {
    delay(500);
  }
  
  Serial.println("connected");
}

void loop() {
  io.run();

  if (millis() > (lastUpdate + IO_LOOP_DELAY)) {
    Serial.println("publishing...");
    counter->save(count);
    lastUpdate = millis();
  }
}

void handleMessage(AdafruitIO_Data *data) {
  Serial.print("received <- ");
  Serial.println(data->value());
}

adafruitio_02_pubsub_trimmed.ino

// Adafruit IO Publish & Subscribe Example
//
// Adafruit invests time and resources providing this open source code.
// Please support Adafruit and open source hardware by purchasing
// products from Adafruit!
//
// Written by Todd Treece for Adafruit Industries
// Copyright (c) 2016 Adafruit Industries
// Licensed under the MIT license.
//
// All text above must be included in any redistribution.

/************************** Configuration ***********************************/

#include "config.h"

// limit publishing speed
#define IO_LOOP_DELAY 5000
unsigned long lastUpdate = 0;

// set up the 'counter' feed
AdafruitIO_Feed *counter = io.feed("counter");

int count = 0;

void setup() {
  Serial.begin(115200);

  // start connecting, delay until connected
  io.connect();
  counter->onMessage(handleMessage);
  while(io.status() < AIO_CONNECTED) {
    delay(500);
  }
  
  Serial.println("connected");
}

void loop() {
  io.run();

  if (millis() > (lastUpdate + IO_LOOP_DELAY)) {
    Serial.println("publishing...");
    counter->save(count);
    lastUpdate = millis();
  }
}

void handleMessage(AdafruitIO_Data *data) {
  Serial.print("received <- ");
  Serial.println(data->value());
}

config.h

#include "AdafruitIO_WiFi.h"

#define IO_USERNAME  ""
#define IO_KEY       ""

#define WIFI_SSID    ""
#define WIFI_PASS    ""

AdafruitIO_WiFi io(IO_USERNAME, IO_KEY, WIFI_SSID, WIFI_PASS);