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BlinkUp Troubleshooting Guide

How To Fix Difficulties Getting Your imp-enabled Device Online

If you are having trouble configuring your imp-enabled device with BlinkUp™, please follow the instructions in this guide.


Some devices signal issues on their LED at start-up. Please see Device-Specific Codes if you are seeing unexpected patterns before BlinkUp.

Choose The Correct BlinkUp App

All imp-enabled devices — which includes your development hardware, factory BlinkUp fixtures and production devices — are configured using BlinkUp. However, not all of these devices are configured using the same BlinkUp implementation. The following table shows the different ways different devices are sent the BlinkUp configuration signal.

BlinkUp... Use... Appears in impCentral ‘My Devices’ List? Device Type
...Your prototype hardware ...The Electric Imp app Yes Developer
...Factory BlinkUp fixture ...The Electric Imp app Yes Developer
...Your product in assembly ...Factory BlinkUp fixture No Production
...Your product in use ...Your BlinkUp app No Production

Performing BlinkUp

When configuring your device with BlinkUp, please ensure the following:

  • The imp-enabled device is powered on.
  • The imp-enabled device’s status LED is blinking. If it is not, you need to restart the device.
  • You have the correct BlinkUp app for the device.
  • You have selected the correct impCloud if you are using the Electric Imp app.
  • You have obtained and entered the correct network SSID and password. Make sure your mobile OS and/or third-party add-ons have not auto-capitalized the first letter of your password — passwords and SSIDs are case-sensitive.
  • You are not trying to connect to a public hotspot or other wireless network that requires you to sign in via a web page — this access mode is not supported by any imp.
  • You are not trying to connect to a network that the imp in the device cannot reach. For example, an imp001 can’t connect to a 5GHz network, though an imp005 can.
  • The screen of your mobile device is as close as possible to the imp-enabled device’s BlinkUp sensor for the entire time the screen is flashing.
  • Your mobile and imp-enabled devices are kept as stationary as possible during BlinkUp.

Common BlinkUp Problems and Their Solutions

Got a Samsung Galaxy S20 or a OnePlus 8? Please see the Android section, below.

Please refer to the imp LED color codes, below.

  • Stuck at ‘No WiFi settings’ (long amber flash)
    • The imp hasn’t received any BlinkUp settings — try BlinkUp again. Try to block out any direct bright lights, or perform a BlinkUp in the shade, and hold the device still during the process.
  • Stuck at ‘Searching for WiFi network’ (long red flash followed by two short red flashes)
    • Check that your network name (SSID) has been entered correctly, making sure that you observe capitalization, special characters etc. imp001-, imp002- and imp003-based devices will only join 2.4GHz WiFi networks. imp005-based devices can connect to both 2.4GHz and 5GHz WiFi networks.
  • Stuck at ‘Joining WiFi network’ (long red flash followed by three short red flashes)
    • Check that your network password has been entered correctly, making sure that you observe capitalization, special characters etc.
  • Stuck at ‘Getting IP address’ (alternating short red and amber flashes)
    • Ensure that DHCP is active on your router and has sufficient IP addresses for all of your devices, including your imp-enabled device. Also check that ‘MAC address filtering’ isn’t enabled, or if it is that it isn’t denying the imp access to the network.
  • Stuck at ‘Resolving server name’ (alternating short amber and red flashes)
    • Check the DNS settings on your router. Devices still running early versions of impOS™ may be confused by the ‘DNS Relay’ mode on some routers — try disabling this mode.
  • Stuck at ‘Connecting to server’ (alternating long amber and short red flashes)
    • Check the firewall settings on your router. The imp needs to make a TCP connection to port 31314; ensure this is not blocked. Only TCP 31314 needs to be open; UDP 31314 can remain closed.
  • Connects to server (green flash), then flashes red, then repeats?
    • This is usually the symptom of a runtime error in the device’s Squirrel code. For developer devices, an error message will be logged in impCentral™ when this happens.
  • Connects to server (green flash), then flashes orange only?
    • This usually indicates that the imp has been rejected by the server:
      • Are you using the wrong type of app? A production device cannot be configured with the Electric Imp mobile app, for example.
  • The LED stays red or flashes red very rapidly?
    • This indicates a power supply issue. The device boots, turns the red LED on and then tries to activate WiFi. However, the WiFi power draw reduces the on-board imp’s operating voltage below tolerance and the imp resets. This continues ad infinitem. Check the power supply feeding your device.

BlinkUp Status Codes

The following table should help you identify the color patterns your device’s BlinkUp status LED may signal. The smallest marked time unit is one quarter of a second.

Note Connections can proceed rapidly, so you may not see all of the patterns your imp can generate. For example, once a WiFi-using imp has successfully connected to WiFi, you may see only a few red and/or orange flashes before the LED steadily flashes green to indicate it is online. What matters for debugging is the pattern being flashed at the point of failure, ie. the last pattern to flash before the LED is powered down.

Current Codes

Pre-BlinkUp and BlinkUp Patterns
No network settings or 
enrollment credentials 
500ms 500ms Repeat
imp005 waiting for Ethernet  500ms 500ms 250ms 250ms Repeat
BlinkUp Successful  For three seconds
WiFi-only Connection Patterns
WPS in progress 
(press WPS button on router) 
500ms 250ms 250ms 250ms Repeat
Searching for WiFi network  500ms 500ms 500ms 250ms 250ms 250ms Repeat
Joining WiFi network  500ms 500ms 500ms 250ms 250ms 250ms 250ms 250ms Repeat
WiFi and Ethernet Connection Patterns
Proxy address or port incorrect  500ms 500ms 250ms 250ms 250ms 250ms Repeat
Proxy credentials rejected  500ms 500ms 250ms 250ms 250ms 250ms 250ms Repeat
Cellular Connection Patterns
Waiting for modem  500ms 500ms 500ms 250ms Repeat
Waiting for SIM  500ms 500ms 500ms 250ms 500ms 250ms 500ms 250ms Repeat
Registering with a cell  500ms 500ms 500ms 250ms 250ms 250ms 500ms Repeat
Cell Registration Denied  500ms 500ms 500ms 500ms 500ms 500ms Repeat
Connecting via PPP  500ms 500ms 500ms 250ms Repeat
Checking PPP connection  500ms 500ms 500ms 250ms 250ms 250ms 250ms 250ms 500ms Repeat
Generic Connection Patterns
Getting IP address  500ms 250ms 250ms Repeat
Resolving server name  500ms 250ms 250ms Repeat
Connecting to server  500ms 500ms 500ms 250ms Repeat
Connected to server  500ms 500ms Repeat
Device lost connection  500ms 500ms Repeat
Device deliberately offline  500ms 250ms 250ms 250ms Repeat
Updating impOS™  Continuous for duration of update
Normal operation  LED not illuminated

A solid red or rapidly flashing red LED indicates a power supply issue.

Device-Specific Codes


imp006s begin life as a version of the STM32F423ZHJ6I MCU that has an impOS loader, called fastROM, pre-installed. At first power up, the fastROM verifies and then copies the impOS firmware image, called impROM, from external SPI flash to the MCU’s internal flash. If the external flash is missing, cannot be read, doesn’t contain an image or contains an image which fails fastROM’s cryptographic checks, the MCU cannot become an imp006. This is indicated on on the host device’s BlinkUp status LED. The pattern it presents is two seconds of solid red. After this the MCU reboots, so the effect will be a slow red blink:

fastROM SPI flash not found  2000ms Reboot

If the ‘impification’ process succeeds, the imp006 is immediately rebooted into impOS, which will from this point show the standard BlinkUp patterns, as appropriate.

Other imps

The imp003, imp004m and imp005 have a number of unique LED codes which signal problems with the SPI flash unit that must be connected to the module. These are displayed when these modules start up and do not relate to BlinkUp. If you are encountering unexpected LED light sequences on a device based on one of these imps, please see the respective Hardware Design Guide:

Once it has been enrolled, an imp005-based device will show the ‘Waiting on Ethernet’ pattern while it is attempting to connect by Ethernet. This is identical to the ‘No WiFi Settings’ pattern indicated by other imps. The imp005 does not support WPS, so will never show the ‘WPS in Progress’ pattern.

Legacy Codes

The following codes are no longer used by modern versions of impOS. They are documented here for users working with imps that may have not been used (and therefore not upgraded) for some time.

No WiFi settings 
(to impOS™ 32) 
500ms 500ms Repeat
BlinkUp™ successful 
(to impOS 30) 
250ms 250ms Repeat for three seconds
BlinkUp unsuccessful 
(to impOS 30) 
250ms 250ms Repeat
Downloading impOS 
(to impOS 30) 
500ms 250ms 250ms 250ms Repeat
Installing impOS 
(to impOS 30) 
Continuous for duration of installation

Android Phones and Tablets

90/120Hz Screen Refresh Rate

The Electric Imp BlinkUp app and the BlinkUp SDK have been updated to support the 90Hz and 120Hz refresh rate offered by a number of Android devices, such as the Samsung Galaxy S20 and the OnePlus 8. However, we have had just a few reports of BlinkUp failing on these phones. If you experience this issue, please let us know and re-try BlinkUp after temporarily disabling 120Hz mode. You can do so by going to Settings > Display > Screen refresh rate. Select Standard for 60Hz, or High to re-enable 120Hz mode.

To apply the setting on a OnePlus phone, go to Settings > Display > Advanced > Refresh Rate.

Older imps

Recent versions of impOS contain many major improvements to BlinkUp on Android devices. Older imps running earlier versions of impOS will not benefit from these improvements until they are updated, a process which can’t take place until your device’s imp has first connected to the Internet after being configured by BlinkUp. If you are having problems configuring a device with an Android phone or tablet, the following may help you get the device to the stage where it can update itself. Ensure:

  • Screen brightness is not set to Auto
  • Screen brightness is at maximum
  • If you have a Samsung phone, Power Saving is off:
    • From the home screen, swipe from top to bottom to open the Quick Settings menu
    • Scroll across the Quick Settings menu until you find ‘Power Saving’
    • If Power Saving is enabled, disable it

These adjustments shouldn’t be necessary when the imp-based device has updated to the latest version of impOS, which will take place when the device first connects successfully. If you are still having problems connecting a device for the first time, try configuring it with an iOS device if you can. This will allow the device update, making future, Android-mediated BlinkUps successful.


For detailed information on imps’ wireless and wired networking requirements, and on issues which may arise during an imp’s attempt to connect to a network, see ‘Network Requirements for imp-enabled Devices’.

Note The imp005 does not support Wireless configuration using WiFi Protected Setup (WPS).


A device’s embedded imp is designed to be driven by a 3.3V DC power supply, commonly derived from a 5V USB feed or from connected batteries. The imp’s operational power range is 1.8-3.6V, but WiFi requires at least 2.5V. If the supply voltage drops below 2.5V, the imp will continue to process Squirrel code (provided the supply is 1.8V or greater) but WiFi will be disabled.

A common source of BlinkUp configuration and connection problems is insufficient power to maintain WiFi while the device makes its initial connection to the Electric Imp impCloud. It is during this process that the device is authorized to connect to the server now and in the future.

Insufficient power at this point can be caused by low batteries, a power supply with insufficient current capacity, or a supply with insufficient voltage. If the power supply can’t support the imp, the imp will attempt to connect, run out of power, reset itself and repeat. This can appear as a fast red blink pattern as the imp quickly reboots over and over again. This LED pattern is a sure message to check your device’s power feed.

BlinkUp Progress

The Electric Imp mobile app shows the device’s progress from configuration to connection is presented on the screen of the phone or tablet you are using to set up the device. When the process completes successfully, the app displays the device’s ID and the URL of its agent. The URL can be shared by SMS or email.