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impOS Downloads

Access the Latest SPI Flash Image For Your Devices

impOS Images

Download the image for your chosen imp module and program it into the SPI flash to pre-install the latest version of impOS™ into devices on your factory’s assembly line at time of first power up.

We recommend pre-programming the SPI flash before SMT is performed. If the device is being programmed after SMT, please follow this process:

  1. Short imp nRESET pin to ground.
  2. Apply power.
  3. Program SPI flash.
  4. Remove power.
  5. Remove short between imp nRESET pin and ground.
  6. Apply power.
  7. imp will ingest image (generally indicated by 10-30 seconds of solid green LED) and reboot.
  8. A flashing amber LED (no network credentials) indicates success.

If you need assistance with installing these images, please reach out to Electric Imp Support.



The imp006 STM32F423ZHJ6I contains a boot stub which ingests a signed and encrypted OS image at time of first boot; the type of imp006 is permanently set by the first boot, so it is important to use the correct image in manufacturing. If you are unsure which image to download for your product, please contact Electric Imp Support.

Note impOS 46.x contains imp006-specific features and so is only available for that module. In all other respects, it is identical to 42.6. For more details, please see the 42.x and 46.x release notes.

Devices purchased from ST distributors or direct from Twilio should use one of these images:

Due to extended leadtimes, we have also enabled a programming partner to load the imp006 bootstrap into STM32F413ZHJ6 and STM32F423ZHJ6 devices that customers have sourced elsewhere. These devices use a different encryption key and so require these different images:

Once the image has been ingested, there is no functional difference between a programming house imp006 and an ST device.

If no image with correct content is found, the imp006 will show a repeating long red, short off LED code at boot. Check the flash content and wiring.



The imp004m requires its SPI flash to be pre-loaded with WiFi firmware in order to operate. This image fits within a 1MB (8Mbit) SPI flash. Due to the time delay between manufacturing of a module and manufacturing of an end device, the imp004m will almost always perform an OTA OS update the first time it gets WiFi credentials.

To skip this upgrade, use this larger impOS image, which includes both WiFi firmware and a signed & encrypted OS image; the downside of this is that it requires a 2MB (16Mbit) or larger SPI flash.


The imp003 holds its WiFi firmware internally at time of manufacture. It will copy this out to the attached SPI flash at first power up to free space for more squirrel code within the internal flash, so there is no need to pre-flash anything to an imp003 SPI flash for manufacturing. However, as with imp004m, the imp003 will likely perform an OTA OS update at first connect. This can be skipped by pre-loading the image below.