Spark stops responding and temperature goes haywire

Troubleshooting
1

Hi,

I built a remote temperature and uptime monitor using a Spark Core that is accessed through a PHP web page. It also has a locally attached alphanumeric LED to show the temperature.

The code includes two spark functions to remotely enable/disable the LED and two spark variables to publish the temperature and uptime and is posted below.

Everything works smoothly; however, after running for somewhere between 2 and 4 days, The system stops functioning. A reflash brings it back to normal, but I donā€™t think re-flashing should be required.

The problem manifests itself as follows:

  1. The temperature reads 492 and never changes. (Clearly this is NOT the actual temperature.)
  2. Uptime is displayed normally
  3. The LED freezes in its last state - If off, it stays off, if on, it stays on shows a temperature that is NOT 492.
  4. The system stops responding to LED on/off requests. --> The cloud JSON response indicates that the request has been received and processed.

As I have pondered the situation, it feels like there is some kind of code issue and perhaps a memory leak. Is there something that jumps out in the code below that could be causing this?

// This #include statement was automatically added by the Spark IDE.
#include "Adafruit_GFX.h"

// This #include statement was automatically added by the Spark IDE.
#include "Adafruit_LEDBackpack.h"

// This #include statement was automatically added by the Spark IDE.
#include "Adafruit_MPL3115A2/Adafruit_MPL3115A2.h"

Adafruit_MPL3115A2 baro = Adafruit_MPL3115A2();
Adafruit_AlphaNum4 alpha4 = Adafruit_AlphaNum4();

float tempF;
int tempFi;
boolean ledonoff = true;
boolean tempupdate = true;
unsigned long previousmillis; 
const long interval = 20000; //update every 20 seconds
char publishString[25];


void setup() {
  alpha4.begin(0x70);

  Spark.variable("Current_T", &tempFi, INT);
  Spark.variable("Uptime",&publishString, STRING);
  Spark.function("ledon", ledon);
  Spark.function("ledoff", ledoff);
  while(! baro.begin()) {
    delay(1000);
  }
  previousmillis = millis() - interval - 1000;
}

void loop() {
    unsigned long currentmillis = millis();
    if (currentmillis - previousmillis > interval){
      previousmillis = currentmillis;
      tempF = baro.getTemperature()*9/5+32;
      tempFi = (int) tempF;
      tempupdate = true;
      sparkPub(currentmillis);
      
    }
    if (ledonoff){
        if (tempupdate){
            displayascii(32,tempFi%100/10+48,tempFi%10+48,32);
            tempupdate = false;
        }
    }
    else{
      displayascii(32,32,32,32);  
    }
      
}

void displayascii(int first, int second, int third, int fourth){
    alpha4.writeDigitAscii(0, first);
    alpha4.writeDigitAscii(1, second);
    alpha4.writeDigitAscii(2, third);
    alpha4.writeDigitAscii(3, fourth);
    alpha4.writeDisplay();
}

void sparkPub(unsigned long now) {
    unsigned nowSec = now/1000UL;
    unsigned sec = nowSec%60;
    unsigned min = (nowSec%3600)/60;
    unsigned hours = (nowSec%86400)/3600;
    unsigned days = (nowSec/86400);
    sprintf(publishString,"%u days, %u:%u:%u",days,hours,min,sec);
}

int ledon(String args2){
    ledonoff = true;
    tempupdate = true;
    return 10;
}

int ledoff(String args2){
    ledonoff = false;
    return 20;
}

Thank you in advance for any thoughts!

2

The first thing I often see is this

Spark.variable("Uptime",&publishString, STRING);

Donā€™t put an ampersand & in front of a character pointer, itā€™s already an address.

But Iā€™ll have some further looks
Edit: nothing major to find anymore, since @peekay123 got greedy and answered it all :+1: :wink:

2 Likes
3

@JL_678, on a quick look:

  1. are you confident that publishString[] NEVER exceeds 25 chars including the terminating ā€˜/0ā€™? Overwriting that array will cause major chaos
  2. Also, have you considered using the Spark Time functions to get ā€œrealā€ time?
  3. You may want to declare ā€œintervalā€ as unsigned long

You may need to add some Serial.print debug messages to see if your barometer and display calls return in a timely fashion. The fact that the temperature is stuck may indicate an issue there.

What intrigues me is the fact that you do a reflash to recover instead of just a reset. So somehow, the code space is being affected. Check the items above and let me know how it goes :smiley:

3 Likes
4

AND @ScruffR beats me to that punch!!! Ok, I missed that oneā€¦ good eye dude! :wink:

3 Likes
5

Hi,

Thank you both for the feedback! A couple of comments:

First, the reset via flash versus the reset button was my choice and so I never actually push the reset button. I can try that next time.

Regarding the array, it used to be 40 characters and I had the same issue. I shrank it because I thought that it might be more memory efficient.

I will implement all of the changes suggested and report back.

Thank you again.

2 Likes
6

Hi,

I have a quick and positive update. After implementing all of your suggested code tweaks, the Spark has been running for 6 days without a problem. (Of course, now I am jinxing myself! :smile: ) I am cautiously optimistic that these enhancements may have addressed the issue.

Thank you!

JL

3 Likes