Device Modes

Now that we've gone over connecting your device, we're going to review the different modes for your Photon. We suggest that you work through this section, putting your device in the different listed modes to familiarize yourself with them.

Standard Modes

These modes are the typical behaviors you will see from your Photon on a regular basis. They are the light patterns of a healthy Photon.

Here's the typical pattern of a Photon after power up.


When it is breathing cyan, your Photon is happily connected to the Internet. When it is in this mode, you can call functions and flash code.

OTA Firmware Update

If your Photon is blinking magenta, it is currently loading an app or updating its firmware. This state is triggered by a firmware update or by flashing code from the Web IDE or Desktop IDE. You might see this mode when you connect your Photon to the cloud for the first time.

Note that, if you enter this mode by holding SETUP on boot, blinking magenta indicates that letting go of the SETUP button will enter safe mode to connect to the cloud and not run application firmware.

Looking For Internet

If your Photon is blinking green, it is trying to connect to the internet. If you already setup the Wi-Fi connection, give your device a few seconds to connect and start breathing cyan.

If you haven't yet connected your Photon to Wi-Fi, then set your device to Listening Mode.

Connecting to the Cloud

When the Photon is in the process of connecting to the cloud, it will rapidly blink cyan. You often see this mode when you first connect your Photon to a network, after it has just blinked green.

Wi-Fi Off

If your Photon is breathing white, the Wi-Fi module is off. You might see this mode if:

  • You have set your module to MANUAL or SEMI_AUTOMATIC in your user firmware
  • You have called in your user firmware

Listening Mode

When your Photon is in Listening Mode, it is waiting for your input to connect to Wi-Fi. Your Photon needs to be in Listening Mode in order to begin connecting with the Mobile App or over USB.

To put your Photon in Listening Mode, hold the SETUP button for three seconds, until the RGB LED begins blinking blue.

Wi-Fi Network Reset

To erase the stored Wi-Fi networks on your Photon, hold the SETUP button for about ten seconds, until the RGB LED blinks blue rapidly.

You can also reset the Wi-Fi networks by holding the SETUP button and tapping RESET, then continuing to hold SETUP until the light on the Photon turns white. (This differs from the Core. Doing this action on the Core will result in a factory reset.)

Safe Mode

Safe mode connects the Photon to the cloud, but does not run any application firmware. This mode is one of the most useful for development or for troubleshooting. If something goes wrong with the app you loaded onto your device, you can set your device to Safe Mode. This runs the Device OS but doesn't execute any application code, which can be useful if the application code contains bugs that stop the device from connecting to the cloud.

The Photon indicates that it is in Safe Mode with the LED breathing magenta.

To put your device in Safe Mode:

  1. Hold down BOTH buttons
  2. Release only the RESET button, while holding down the SETUP button.
  3. Wait for the LED to start blinking magenta
  4. Release the SETUP button

The device will itself automatically enter safe mode if there is no application code flashed to the device or when the application is not valid.

DFU Mode (Device Firmware Upgrade)

If you wish to program your Photon with a custom firmware via USB, you'll need to use this mode. This mode triggers the on-board bootloader that accepts firmware binary files via dfu-util (Note: Some users reported issues with dfu-util on a USB3.0 ports on Windows. Use a USB2.0 port if the USB3.0 port doesn't work.)

Installation tutorial can be found here.

And a usage guide here.

To enter DFU Mode:

  1. Hold down BOTH buttons
  2. Release only the RESET button, while holding down the SETUP button.
  3. Wait for the LED to start flashing yellow (it will flash magenta first)
  4. Release the SETUP button

The Photon now is in the DFU mode.

Firmware Reset

Firmware reset is not available on the Photon, but not to worry! If you are experiencing problems with your application firmware, you can use Safe Mode to recover.

Factory Reset

Factory reset is not available on the Photon, but not to worry! If you are experiencing problems with your application firmware, you can use Safe Mode to recover.

You can reset Wi-Fi credentials by performing a Wi-Fi Network Reset.

Troubleshooting Modes

These modes let you know about more atypical issues your Photon might be exhibiting. Use this section to troubleshoot strange colors you might see from your Photon.

Wi-Fi Module Not Connected

If the Wi-Fi module is on but not connected to a network, your Photon will be breathing blue. Note that this will be dark blue and not cyan.

Cloud Not Connected

When the Photon is connected to a Wi-Fi network but not to the cloud, it will be breathing green.

This can be caused by the currently running application firmware which may interfere with the cloud maintenance tasks which are usually executed between iterations of loop() or via an explicit call of Particle.process(). That commonly happens when the code blocks for more than 10 seconds. In addition to regularly allowing for cloud maintenance (via dropping out of loop() and/or calling Particle.process()) you can take manual control of the connection, choose a better suited SYSTEM_MODE and/or opt for SYSTEM_THREAD(ENABLED). To correct the "offending" firmware you may need to flash new firmware either via USB or Safe Mode.

Bad Public Key

When the server public key is bad, the Photon will blink alternately cyan and red.

Blinking red indicates various errors.

  • 2 red blinks: Could not reach the internet.
  • 3 red blinks: Connected to the internet, but could not reach the Particle Device Cloud.
  • Blinking "orange": This sometimes is seen as yellow or red and indicates bad server keys. To fix this issue, use the Particle CLI to restore the server keys using particle keys server in your terminal window, while having the device in DFU mode.

Red Flash SOS

Is your Photon blinking red? Oh no!

A pattern of more than 10 red blinks is caused by the firmware crashing. The pattern is 3 short blinks, 3 long blinks, 3 short blinks (SOS pattern), followed by a number of blinks that depend on the error, then the SOS pattern again.

Enter safe mode, tweak your firmware and try again!

There are a number of other red blink codes that may be expressed after the SOS blinks:

  1. Hard fault
  2. Non-maskable interrupt fault
  3. Memory Manager fault
  4. Bus fault
  5. Usage fault
  6. Invalid length
  7. Exit
  8. Out of heap memory
  9. SPI over-run
  10. Assertion failure
  11. Invalid case
  12. Pure virtual call
  13. Stack overflow

The two most common ones are:

Hard Fault (1 blink between 2 SOS patterns)

Out of heap memory (8 blinks between 2 SOS patterns)

If your Photon crashes repeatedly with an SOS code, first try recovering with Safe Mode and flashing Tinker with the CLI to see if it was something recently added in your user application.

particle flash <mydevice> tinker

If it's not possible to enter Safe Mode, your Device OS may be corrupted. Use the Device Doctor feature of the CLI to put your Photon into a healthy state.

particle device doctor

Don't forget that the community forum is always there to help.