Rapidly blinking dark blue status LED?

I have started seeing a new behavior with both of my trusty Photons where I get a rapidly-blinking dark blue status LED after flashing a new program.

Does this indicate a specific status?


I only know rapid blue from resetting the WiFi credentials by holding the SETUP botton for 10+ seconds. Could it be that your code is reprogamming the BTN pin?

It is a rapid blink, not the same blinking that the Photon does during listening mode.

It seems unlikely that the code is reprogramming the button pin. Unless it’s happening as a result of some kind of memory leak or other badness in the Blynk library/code. However, it was all working just dandy a week ago.

There’s definitely something happening when I flash that new code.

I’d like to hear from Particle regarding how to interpret a rapid dark blue blinking status LED.


I know, that’s why I said during “WiFi credentials reset”. When you hold SETUP for 3-10 seconds the device enters Listening Mode where it flashes blue slowly, but if you hold it for more than 10 seconds it will start blinking blue rapidly (~10Hz) while it is clearing the WiFi creds.

Maybe you can post a video of the process.
You can also try to reflash Tinker to your Photon.

that’s why I said during “WiFi credentials reset”.

Ooops! Sorry, missed that detail. Yes, maybe that’s what it is doing.

I believe that I have narrowed it down to the Blynk library. That is, I have a sketch that will work until I start the Blynk connection, and then it goes out to lunch.

What’s odd is that it was working last week, but then I updated the Device OS on my Photon. I wonder if there is a compatibility issue with the version I am using now (0.7.0) and Blynk. Might be worth reverting back to 0.6.2 which is what was on the Photon before the update.

This might be just an edge case where your application was nearly using all the free space for 0.6.2, but since 0.7.0 needs some extra space and consequently nibbles away from the available application space this strange side effect might occure.

Have you also recompiled your application against 0.7.0?

Yes, I have recompiled it for 0.7.0. It’s a very short sketch. I can make it crash with the basic Blynk template code - which has been historically very solid.

Here’s a video I created to show the failure: https://youtu.be/flr_34Bg4Fk

I’ll likely write up a description of this whole thing and create a new forum post both here and on the Blynk forums tomorrow.


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In the video I can’t quite make out whether this is cyan or blue.
But for you this is definetly the same blue as Listening Mode just flashing this fast, right?

Yes, it is dark blue. The WiFi Listening Mode blue. Not cyan.
And yes, fast blinking.

If I hit the reset button, it will return to the slow Listening Mode blink speed. But the WiFi credentials are gone.

That backs up my first interpretation

Although it doesn’t explaint why this is happening. It seems as if code is branching off into the function that’s also executed via the SETUP 10+ hold-down.
If you could share your code, this would be an interesting bug to track (@rickkas7?)

The entirety of the code is shown in the video and is available from the Blynk.cc website:


It’s pretty basic:

/* Comment this out to disable prints and save space */
#define BLYNK_PRINT Serial

#include <blynk.h>

// You should get Auth Token in the Blynk App.
// Go to the Project Settings (nut icon).
char auth[] = "[REMOVED FOR POST]";

void setup()
  // Debug console

  delay(5000); // Allow board to settle

void loop()
  // You can inject your own code or combine it with other sketches.
  // Check other examples on how to communicate with Blynk. Remember
  // to avoid delay() function!

I created a separate post with better description of the specific Blynk-related behavior and video URL here:

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I was able to eliminate this behavior by implementing the recommendations provided by @peekay123 in his response to my other thread:

This doesn’t really help me understand WHY the issue was happening in the first place, but as a workaround it solve my immediate problem and enables me to move forward. So, I’d consider this thread closed.

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