Arduino crashing during serial print

Question

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. 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(&quot;Attempting to connect to GSM and GPRS&quot;);
// 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) &amp;&amp;
            (gprs.attachGPRS() == GPRS_READY)) {
        connected = true;
    } else {
        Serial.println(&quot;Not connected&quot;);
        delay(1000);
    }
}

Serial.println(&quot;You're connected to the network&quot;);
Serial.println();

Serial.print(&quot;Attempting to connect to the MQTT broker: &quot;);
Serial.println(broker);

if (!mqttClient.connect(broker, port)) {
    Serial.print(&quot;MQTT connection failed! Error code = &quot;);
    Serial.println(mqttClient.connectError());

    while (1)
        ;
}

Serial.println(&quot;You're connected to the MQTT broker!&quot;);
Serial.println();

// set the message receive callback
mqttClient.onMessage(onMqttMessage);

Serial.print(&quot;Subscribing to topic: &quot;);
Serial.println(subscribeTopic);
Serial.println();

// subscribe to a topic
mqttClient.subscribe(subscribeTopic);

Serial.print(&quot;Waiting for messages on topic: &quot;);
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 &gt; 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 = &quot;&quot;;
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

}

The output looks as follows when it gets stuck:

Arduino crashing during serial print

0 Answers0