Connecting Arduino Nano 33 IoT to AWS IoT Using MQTT Protocol

[jacobtprice20]

I am attempting to connect my Arduino Nano 33 IoT to the AWS IoT Cloud service. I have been using the following article as a guideline for setup:

[ https://docs.arduino.cc/tutorials/mkr-wifi-1010/securely-connecting-an-arduino-mkr-wifi-1010-to-aws-iot-core]

I have followed these steps exactly, modifying the code to include my AWS broker endpoint, the proper wifi credentials, and the certificate information. However, I am running into a problem with the mqtt connection. Upon using the mqttClient.connectError() function, the error statement is as follows:

"Attempting to connect to MQTT broker: a4gwbsni06dqq-ats.iot.us-east-1.amazonaws.com

.Failed to connect to MQTT broker. Error code: -2

Invalid certificate. Check the certificate validity and broker address."

Has anyone encountered a similar issue? Is there something I should change in my code (maybe switch to Wifi101 instead of WifiNINA library)? Is it possible that there is an issue with the network configuration (firewall access)? Some sort of naming convention?

My code, obtained directly from the above article, is here:

/*
  AWS IoT WiFi

  This sketch securely connects to an AWS IoT using MQTT over WiFi.
  It uses a private key stored in the ATECC508A and a public
  certificate for SSL/TLS authetication.

  It publishes a message every 5 seconds to arduino/outgoing
  topic and subscribes to messages on the arduino/incoming
  topic.

  The circuit:
  - Arduino MKR WiFi 1010 or MKR1000

  The following tutorial on Arduino Project Hub can be used
  to setup your AWS account and the MKR board:

  https://create.arduino.cc/projecthub/132016/securely-connecting-an-arduino-mkr-wifi-1010-to-aws-iot-core-a9f365

  This example code is in the public domain.
*/

#include <ArduinoBearSSL.h>
#include <ArduinoECCX08.h>
#include <ArduinoMqttClient.h>
#include <WiFiNINA.h> // change to #include <WiFi101.h> for MKR1000

#include "arduino_secrets.h"

/////// Enter your sensitive data in arduino_secrets.h
const char ssid[]        = SECRET_SSID;
const char pass[]        = SECRET_PASS;
const char broker[]      = SECRET_BROKER;
const char* certificate  = SECRET_CERTIFICATE;

WiFiClient    wifiClient;            // Used for the TCP socket connection
BearSSLClient sslClient(wifiClient); // Used for SSL/TLS connection, integrates with ECC508
MqttClient    mqttClient(sslClient);

unsigned long lastMillis = 0;

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

  if (!ECCX08.begin()) {
    Serial.println("No ECCX08 present!");
    while (1);
  }

  // Set a callback to get the current time
  // used to validate the servers certificate
  ArduinoBearSSL.onGetTime(getTime);

  // Set the ECCX08 slot to use for the private key
  // and the accompanying public certificate for it
  sslClient.setEccSlot(0, certificate);

  // Optional, set the client id used for MQTT,
  // each device that is connected to the broker
  // must have a unique client id. The MQTTClient will generate
  // a client id for you based on the millis() value if not set
  //
  // mqttClient.setId("clientId");

  // Set the message callback, this function is
  // called when the MQTTClient receives a message
  mqttClient.onMessage(onMessageReceived);
}

void loop() {
  if (WiFi.status() != WL_CONNECTED) {
    connectWiFi();
  }

  if (!mqttClient.connected()) {
    // MQTT client is disconnected, connect
    connectMQTT();
  }

  // poll for new MQTT messages and send keep alives
  mqttClient.poll();

  // publish a message roughly every 5 seconds.
  if (millis() - lastMillis > 5000) {
    lastMillis = millis();

    publishMessage();
  }
}

unsigned long getTime() {
  // get the current time from the WiFi module  
  return WiFi.getTime();
}

void connectWiFi() {
  Serial.print("Attempting to connect to SSID: ");
  Serial.print(ssid);
  Serial.print(" ");

  while (WiFi.begin(ssid, pass) != WL_CONNECTED) {
    // failed, retry
    Serial.print(".");
    delay(5000);
  }
  Serial.println();

  Serial.println("You're connected to the network");
  Serial.println();
}

void connectMQTT() {
  Serial.print("Attempting to connect to MQTT broker: ");
  Serial.println(broker);

  while (!mqttClient.connect(broker, 8883)) {
    // failed, retry
    Serial.print(".");
    delay(5000);

    // Check the reason for the connection failure
    int connectError = mqttClient.connectError();
    if (connectError != 0) {
      Serial.print("Failed to connect to MQTT broker. Error code: ");
      Serial.println(connectError);

      }
    }
  }

  Serial.println();
  Serial.println("You're connected to the MQTT broker");
  Serial.println();

  // subscribe to a topic
  mqttClient.subscribe("arduino/incoming");
}



void publishMessage() {
  Serial.println("Publishing message");

  // send message, the Print interface can be used to set the message contents
  mqttClient.beginMessage("arduino/outgoing");
  mqttClient.print("hello ");
  mqttClient.print(millis());
  mqttClient.endMessage();
}

void onMessageReceived(int messageSize) {
  // we received a message, print out the topic and contents
  Serial.print("Received a message with topic '");
  Serial.print(mqttClient.messageTopic());
  Serial.print("', length ");
  Serial.print(messageSize);
  Serial.println(" bytes:");

  // use the Stream interface to print the contents
  while (mqttClient.available()) {
    Serial.print((char)mqttClient.read());
  }
  Serial.println();

  Serial.println();
}