I am trying to determine why my Arduino MKR NB 1500 code keeps crashing when the serial monitor is open and i look for data: Here is the code. I removed the string functions to prevent it from causing memory fragmentation, but does not seems to have helped.
#include <ArduinoMqttClient.h>
#include <MKRNB.h>
// Please enter your sensitive data in the Secret tab or arduino_secrets.h
// PIN Number
const char PINNUMBER[] = "";
// MQTT Broker and Port
const char broker[] = "test.mosquitto.org"; //
int port = 1883;
// Pub/Sub Topics - Make it something unique since we are using a public broker
const char subscribeTopic[] = "channel";
const char publishTopic[] = "channel";
// To connect with SSL/TLS:
// 1) Change NBClient to NBSSLClient.
// 2) Change port value from 1883 to 8883.
// 3) Change broker value to a server with a known SSL/TLS root certificate
// flashed in the WiFi module.
NBClient client;
GPRS gprs;
NB nbAccess;
MqttClient mqttClient(client);
int LED = 6; // Onboard LED
// Publish interval
long previousMillis = 0;
long interval = 2000;
void setup() {
pinMode(LED_BUILTIN, OUTPUT); // Set built in LED pinMode
//Initialize serial and wait for port to open:
Serial.begin(9600);
/* while (!Serial) {
; // wait for serial port to connect. Needed for native USB port only
}*/
// attempt to connect to GSM and GPRS:
Serial.print("Attempting to connect to GSM and GPRS");
// connection state
bool connected = false;
// After starting the modem with GSM.begin()
// attach the shield to the GPRS network with the APN, login and password
while (!connected) {
if ((nbAccess.begin(PINNUMBER) == NB_READY) &&
(gprs.attachGPRS() == GPRS_READY)) {
connected = true;
} else {
Serial.println("Not connected");
delay(1000);
}
}
Serial.println("You're connected to the network");
Serial.println();
Serial.print("Attempting to connect to the MQTT broker: ");
Serial.println(broker);
if (!mqttClient.connect(broker, port)) {
Serial.print("MQTT connection failed! Error code = ");
Serial.println(mqttClient.connectError());
while (1);
}
Serial.println("You're connected to the MQTT broker!");
Serial.println();
// set the message receive callback
mqttClient.onMessage(onMqttMessage);
Serial.print("Subscribing to topic: ");
Serial.println(subscribeTopic);
Serial.println();
// subscribe to a topic
mqttClient.subscribe(subscribeTopic);
Serial.print("Waiting for messages on topic: ");
Serial.println(subscribeTopic);
Serial.println();
}
void loop() {
unsigned long currentMillis = millis();
// call poll() regularly to allow the library to receive MQTT messages and
// send MQTT keep alives which avoids being disconnected by the broker
mqttClient.poll();
// Enforce Interval
if(currentMillis - previousMillis > interval) {
previousMillis = currentMillis;
// Call a function that handles publishing message
publishSensorVal();
}
}
void publishSensorVal() {
// read the first Analog pin
int sensorVal = analogRead(0);
//String speak = "The sensor val is " + String(sensorVal);
char adc_sv[30] = {'T', 'h', 'e', ' ', 'a', 'd', 'c', ' '' ', 'v', 'a', 'l', 'u', 'e', ' ', 'i', 's', ' ', '\0'}; //adc_step value
// Publish our sensor value to the publish topic
mqttClient.beginMessage(publishTopic);
mqttClient.print(adc_sv);
mqttClient.print(sensorVal);
mqttClient.endMessage();
digitalWrite(LED_BUILTIN, HIGH); // turn the LED on (HIGH is the voltage level)
delay(1400); // wait for a second
digitalWrite(LED_BUILTIN, LOW); // turn the LED off by making the voltage LOW
delay(100); // wait for a second
}
void handleCommand(String cmd) {
if (cmd == "on"){
digitalWrite(LED, HIGH);
}else if(cmd == "off"){
digitalWrite(LED, LOW);
}
}
void onMqttMessage(int messageSize) {
// we received a message, print out the topic and contents
Serial.println("Received a message with topic '");
Serial.print(mqttClient.messageTopic());
Serial.print("', length ");
Serial.print(messageSize);
Serial.println(" bytes:");
// We want to read each character into a useable String
String content = "";
char character;
// use the Stream interface to print the contents
while (mqttClient.available()) {
character = (char)mqttClient.read();
content.concat(character);
}
handleCommand(content); // This function does something with our incoming string
Serial.println(content);
Serial.println(); Serial.println(); // double spacing
}
