Photon blinking blue with power shield [RESOLVED]

we have this weird issue that when using the particle power shield the photon blinks blue. i can “add” the device (with the particle iphone app) again (although it seems to be slower connecting giving “error connecting”) and flash it again and working fine. but when i power cycle it is back at blinking blue. this problem started with the power shield but continues now even without the shield. i tried another photon and got the same issue. (btw: the code i flash is pretty much just reading out the voltage and state-of-charge and publishing those values)
anyone any idea?

Try clearing the credentials and set them again via CLI or a serial terminal programm.

More help might be possible if we saw the code
Meanwhile revert back to Tinker via

particle flash --usb tinker

hi scruffr,
code below. i do not think it is the code as it runs on a photon without shield without problems/blinking blue. clearing credentials does not help. well, it does help in the sense that i can reflash but after power-cycle it is blinking blue again (even without power shield).

#include <PowerShield.h>

PowerShield batteryMonitor;


void setup() {


    pinMode(D7, OUTPUT);
    digitalWrite(D7, LOW);

void loop() {
    float cellVoltage = batteryMonitor.getVCell();
    float stateOfCharge = batteryMonitor.getSoC();
    Serial.print("dummy event ");
    Serial.println("version 26 jan 2017...");   
    digitalWrite(D7, HIGH);
    digitalWrite(D7, LOW);

Can you post a video of the startup process and the blinking blue?
I can have a check with your code, but I never had such an issue with the Particle Power Shield.

after powering it immediately blinks blue

i am able to get the photon back to normal with the “hold setup for 10 seconds” reset while blinking blue. after 10 seconds i see it fast blinking blue. then i use the phone app to add the photon again and flashing tinker. after that i can restart the photon! (blinking cyan, not blinking blue)

still very much interested why/how these photons came into this mode with the power shield.


I'm not sure it was actually caused by the power shield itself.

That blinking blue indicates that there are no credentials stored in the WiFi module's flash memory.
But since you reported the device could get onto the network once suggests that the data was stored in the module's RAM.
This seems to indicate that the credentials validation before storing the data failed although the creds were correct so subsequent connection attempts finally got you connected.
This also fits to that statement

This can happen with hidden SSID networks, flaky radio or low battery where the single validation check might timeout and so fail to save the creds but subsequent attempts may succeede and get you connected.

hi scruffr,
considering all we think it was related to wifi.clearcredentials() we had in the code before. we used this to make sure we had credentials for the different networks. this code was used on these photons before but no longer in de code when we had this issue. after “restoring” the photon and using it again with the same code as above and it now works without issue.

This was the reason why I asked to see your code and reflash Tinker.
But showing some "arbitrary/unrelated" code does not help helping, does it?

the weird thing is that that was the previous code, not the actual code with which we got the problem (that was exactly as posted)

thanks for you help