Add AWS IoT GSM example

Author: sandeepmistry

examples/AWS IoT/AWS_IoT_GSM/AWS_IoT_GSM.ino

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+/*
+  AWS IoT GSM
+
+  This sketch securely connects to an AWS IoT using MQTT over GSM/3G.
+  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:
+  - MKR GSM 1400 board
+  - Antenna
+  - SIM card with a data plan
+  - LiPo battery
+
+  This example code is in the public domain.
+*/
+
+#include <ArduinoBearSSL.h>
+#include <ArduinoECCX08.h>
+#include <ArduinoMqttClient.h>
+#include <MKRGSM.h>
+
+#include "arduino_secrets.h"
+
+/////// Enter your sensitive data in arduino_secrets.h
+const char pinnumber[]     = SECRET_PINNUMBER;
+const char gprs_apn[]      = SECRET_GPRS_APN;
+const char gprs_login[]    = SECRET_GPRS_LOGIN;
+const char gprs_password[] = SECRET_GPRS_PASSWORD;
+const char broker[]        = SECRET_BROKER;
+const char* certificate    = SECRET_CERTIFICATE;
+
+GSM gsmAccess;
+GPRS gprs;
+
+GSMClient     gsmClient;            // Used for the TCP socket connection
+BearSSLClient sslClient(gsmClient); // 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 (gsmAccess.status() != GSM_READY || gprs.status() != GPRS_READY) {
+    connectGSM();
+  }
+
+  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 GSM module
+  return gsmAccess.getTime();
+}
+
+void connectGSM() {
+  Serial.println("Attempting to connect to the cellular network");
+
+  while ((gsmAccess.begin(pinnumber) != GSM_READY) ||
+         (gprs.attachGPRS(gprs_apn, gprs_login, gprs_password) != GPRS_READY)) {
+    // failed, retry
+    Serial.print(".");
+    delay(1000);
+  }
+
+  Serial.println("You're connected to the cellular network");
+  Serial.println();
+}
+
+void connectMQTT() {
+  Serial.print("Attempting to MQTT broker: ");
+  Serial.print(broker);
+  Serial.println(" ");
+
+  while (!mqttClient.connect(broker, 8883)) {
+    // failed, retry
+    Serial.print(".");
+    delay(5000);
+  }
+  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();
+}

examples/AWS IoT/AWS_IoT_GSM/arduino_secrets.h

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+// GSM settings
+#define SECRET_PINNUMBER     ""
+#define SECRET_GPRS_APN      "GPRS_APN" // replace your GPRS APN
+#define SECRET_GPRS_LOGIN    "login"    // replace with your GPRS login
+#define SECRET_GPRS_PASSWORD "password" // replace with your GPRS password
+
+// Fill in the hostname of your AWS IoT broker
+#define SECRET_BROKER "xxxxxxxxxxxxxx.iot.xx-xxxx-x.amazonaws.com"
+
+// Fill in the boards public certificate
+const char SECRET_CERTIFICATE[] = R"(
+-----BEGIN CERTIFICATE-----
+
+-----END CERTIFICATE-----
+)";