Flashing green at random times after breathing cyan

I’ve got my spark core online, and I’m playing around with it, and did a few small things, so that’s exciting. However, every time I come back to it after being gone for a while, it’s gone to flashing green. I hit the RST button, and it goes through its bootup and loads my program again (verified because I flash D7 10 times) and then it goes to breathing cyan and is fine. I don’t have an exact timeframe of how long it will take to go flashing green, but it does it pretty regularly for say, overnights. Any ideas where to look?

Hi @aaronw,

Sounds like your core is dropping off your wifi periodically. I know this thread has been debugging a similar issue here: https://community.spark.io/t/bug-bounty-kill-the-cyan-flash-of-death/1322/235

It might be worth checking to see what channel your access point is on, just to make sure there isn’t a lot of interference with other nearby networks. I believe the more recent firmware does a better job of re-connecting, so it might be worth tweaking your code / re-flashing your core if you haven’t recently.


Just out of curiosity, are you using any delays at all? If you delay() the code too much this happens as well.

I have some delays in the startup code (to flash the D7) and a delay when the API is used with an invalid parameter (red-green-white flash) but no delays that are called in the loop during normal operation.

So I have two APs for my SSID, on channel 1 and channel 6 (different parts of the house). Both of them are at least 10db above any other contenders on the same channel, and usually 15-20 above. Netstumblr doesn’t really find any other loud sources on the spectrum near me… How do I check what version of the firmware I have on the core?

Cool, thanks for checking that!

I think right now that info doesn’t get exposed through the API, so the easiest way if you’re running custom firmware from the build site, would be to re-verify / flash the code to your core after making a small change (so it rebuilds).

I’m aware of some networking bugs, but I don’t think those would apply if you were totally disconnected from the access point. (flashing green)

I get this too. But sometimes even a restart of my router and/or the core doesn’t fix it. It seems to just eventually resolve itself.

Ok, I made a change to the code and sent it down. Is there a way from the build.spark.io site to see when the core has started running the code? or finished the download?

Does flashing green really mean disconnected from access point? If I call Spark.disconnect() I get flashing green, even though I can still communicate over UDP

Same here.

I received my Spark Core and get the fast flashing Green light eventually after being successfully connected to my wifi network. Once the spark core shows the fast flashing green LED it will not automatically reconnect to the wifi network, it will just sit there and flash for ever.

I can turn my router on and off again and it will not affect the green flashing light, or make the Spark Core connect to the network automatically after the rest. I can reset the the spark core manually and it will instantly successfully connect to my wifi network.

So it seems that the Spark Core does not have the ability to keep a successful connection to a WiFi Network based on me trying to maintain one for even a few hours which makes the chip basically worthless if you want to use it for anything reliable.

I have confidence that this will be resolved eventually but it sure does suck that it does not work out of the box.

I am running the LED Blink sketch, with a 1 min on/off delay.

Hopefully this gets up and running sooner rather than later!

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I only received my cores a few days ago so still working though some aspects. I have found that the use of the delay with values over 7sec (7000ms) consistently cause non recoverable flashing green for me. The actual time may be different for others as I have a very slow internet connection (satellite) where a good ping time is 750ms.

Hey DeanCS, yes I didn’t experience the green flashing near as much until I changed the Delay to 10000ms.

I reset the SparkCore to factory fresh and uploaded the LED Blink Sketch with a 1000ms delay instead. I’ll monitor the frequency of the wifi disconnect and green flashing LED without reconnecting and provide the data for others to troubleshoot.

Hi @RWB,

We have a bunch of posts about this, but the core does a heartbeat check with the server every 15 seconds to make sure you’re online. If your core had a 60 second delay, it will constantly be disconnecting from the cloud! – Edit: Oops, just saw your latest post, yup, right now lower delays == successful heartbeats


Hi @dermotos,

Hmm, maybe that’s my bad then. I thought flashing green meant no wifi connection yet. Maybe I’d better review that code again and refresh my memory. :smile:


Just experience the same problem on my core.
Does not seem to be software specific… have tried some different software’s and they runs fine.
But after a while the program freeze up and the core goes to green flashing.

I can’t see any logic in the time as sometimes the software works for an hour and sometimes it freeze up after a few minutes (same software).