Durability of a core running 24x7

Hi all.
If I have a core powered by 5v AC wall adapter running 24x7 a day how long of a service can I expect from it? In other words what is the lifespan of a core that is running 24x7 a day and 365 days a year??

Thanks

@bijay I would imagine that the core would be fine for a very long time if you ensure it has proper ventilation and proper protection against electrical surges. I have had cores running 24/7 for months w/o any electrical failure. Keep in mind that If you have sensors and if the core is located outside then you need to make sure you protect the core from any transient electrical noise that may cause failure - such as electrical storms.

The Core firmware is designed to automatically recover from different error cases, so durability/reliability may rely more on use code than anything. One technique I’ve employed with success over the years in products is to simply reset the device if it’s just sitting there idle for long periods of time. When you get deep into safety (and reliability) of a product, you start to question things like what happens if a cosmic ray/power spike/ESD flips a random bit in RAM and causes your code to execute abnormally? A periodic reset forces the stars of your application to realign. This doesn’t typically affect the operation, but your mileage may vary… think about how this affects your application and how you might be able to use it. Essentially a periodic or programatic reset looks like this:

// Spark Core Periodic Reset
// -------------------------

#include "application.h"

uint32_t lastReset = 0;

void setup() {
    lastReset = millis();
} // end setup()

void loop() {

    // Reset after 5 minutes of operation
    // ==================================
    if (millis() - lastReset > 5*60000UL) {
        System.reset();
    }

} // end loop()
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I get hit with cosmic rays all the time, now you make me wonder if that is thy I periodically have to reboot myself :smile:

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@BDub, I think @bijay was looking for the Core’s hardware MTBF which I suspect is in the order of 10+ years if properly cared for. The wall wart will fail before the Core does.

As for safety, I have two teenage boys that regularly cause me to hard fault and force a reboot. :wink:

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If properly cared for, I would imagine the USB connector would wear out first… if you prototyped with it continuously. If you built a project and committed a Spark Core to it… the hardware would last “forever”. There are no electrolytic caps on the board to dry out. Even if they did have caps, I have 35 - 45 year old electronics full of electrolytic caps that still power up today and run just like they did back in the day. YMMV with electrolytic based on the quality you start with, but here we’re not talking about them anyway :slight_smile: I realize this is not all very scientific, but an actual MTBF number would be best found with some accelerated life testing and larger sample sets. Also, what are we considering a “failure” in the Spark Core exactly? Data glitch, some API not working, total system failure (i.e. won’t boot)?

Some of the MTBF data can be estimated based on work that the MFG’s of the components of the Spark Core have already done… for instance the CC3000 Wi-Fi module, is something like 4.67*10^8 hours (i.e., “forever”)
http://focus.ti.com/quality/docs/singlesearchresults.tsp?&templateId=5909&navigationId=11213&appType=folders&searchType=orderableOption&partialSearch=false&mtbfType=true&orderablePartNumber=CC3000MOD

The MTBF for a 10V tantalum capacitor on a 5V bus is something well over 1000 years.

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@BDub, it always turns out to be something mechanical like a solder joint or connector or an power event which causes a failure. The worst culprits are dust and humidity and temperature cycling (large swings). If those are managed, the Spark will last longer than the OP’s need for it. :wink:

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Thanks @peekay123. This is exactly what I was looking for.

Thank u @BDub. Its good to know that the core has a very longer MTBF.

I’ve noticed over the years that if I leave my PC’s on continuously for years they seem to last as long or longer than PC’s which are switched off every day. I guess that is due to all the electrical expansion when the PCB is turned on and heats up.

With the Indoor Air Quality shield I am assuming that having the ability to turn off the sensors to reduce heat will also have the side effect of increasing their lifespan - but I guess time will tell.

My experience (as I ran a datacenter in NYC) was not power cycling but moving parts failing - fans, HDD’s etc. The electronics only failed due to power failures, surges, or overheating. Now there have been PWS problems but that was poor design (components operating above their ratings).
Mostly 10v caps running at 16v and designs like that.