nRF9160: HTTP modem delta update

The HTTP modem delta update sample demonstrates how to do a delta update of the modem firmware. A delta update is an update that contains only the code that has changed, not the entire firmware.

The sample uses the FOTA download library to download a file from a remote server and write it to the modem.


The sample connects to an HTTP server to download a signed modem delta image. The delta images are part of the official modem firmware releases. The sample will automatically download the correct delta image to go from the base version to the test version, or the test version to the base version, depending on the currently installed version.


The sample supports the following development kit:

Hardware platforms


Board name

Build target

nRF9160 DK




The sample is configured to compile and run as a non-secure application on nRF91’s Cortex-M33. Therefore, it automatically includes the Secure Partition Manager that prepares the required peripherals to be available for the application.

You can also configure it to use TF-M instead of Secure Partition Manager.

Building and running

This sample can be found under samples/nrf9160/http_update/modem_delta_update in the nRF Connect SDK folder structure.

See Building and programming a sample application for information about how to build and program the application.

The sample is built as a non-secure firmware image for the nrf9160dk_nrf9160ns build target. Because of this, it automatically includes the Secure Partition Manager.


After programming the sample to your development kit,, test it by performing the following steps:

  1. Note the LED pattern (1 or 2 LEDs).

  2. Press button 1 to download the delta for the alternative firmware version.

  3. Once the download has been completed, follow the reboot instructions printed to the UART console.

  4. Observe that the LED pattern has changed (1 vs 2).

  5. Start over from point 1, to perform the delta update back to the previous version.


This sample uses the following nRF Connect SDK libraries:

It uses the following sdk-nrfxlib library:

It uses the following Zephyr libraries: