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Zephyr Integration Guide

This tutorial will go over integrating the Memfault Firmware SDK into a system that is using Zephyr RTOS.


If you are using a Nordic Semiconductor chip and the nRF Connect SDK, take a look at the nRF Connect SDK Integration Guide for details specific to that setup!


This guide assumes the following:

  • Zephyr toolchain is setup on the host machine
  • knowledge of building and configuring Zephyr applications
  • a target board with a supported architecture; any Cortex-M series device should be supported, for other architectures please contact us.

Supported Zephyr Versions

Memfault targets supporting new Zephyr releases as they arrive. If a version is not included below, please contact us and we'll let you know the status!

  • ✅ >= v2.0.0, <= v3.6.0 tested and supported

Adding the Memfault Module

Adding the Memfault SDK to your project as simple as adding this snippet to your west.yml:


# Add the Memfault GitHub repo
- name: memfault
# Add the Memfault SDK
- name: memfault-firmware-sdk
path: modules/lib/memfault-firmware-sdk
revision: 0.43.3
remote: memfault

Depending on your project setup, the west.yml file may be in the application repository (most common), or in a separate manifest repository. Read more about supported development repositories here:

After updating the West Manifest, run 👉west update👈 to pull in the Memfault SDK. Double check that you see the SDK source folder memfault-firmware-sdk under modules/lib/.

Enabling Memfault

To enable Memfault, set the required Kconfig options:

# Memfault configuration

And the minimal dependency function, which should be added to your project source (for example, in your main.c file):

#include <memfault/components.h>

// A hard-coded set of device information. In production, at minimum the
// device_serial would usually be device-specific and set at runtime.
void memfault_platform_get_device_info(sMemfaultDeviceInfo *info) {
*info = (sMemfaultDeviceInfo){
.device_serial = "DEMOSERIAL",
.software_type = "zephyr-app",
.software_version = "1.0.0-dev",
.hardware_version = CONFIG_BOARD,

Testing the Integration

The next step is to generate some Memfault data and verify it's decoded correctly in the Memfault cloud. To do that, we first need to upload the generated symbol file (for Zephyr projects, it's build/zephyr/zephyr.elf), then trigger some test data collection on device, and then upload the data to Memfault for analysis.

Upload Symbol File

At this point, you should be able to generate test events and crashes and push the data to the Memfault UI.

You can confirm the error traces and crashes have arrived successfully by navigating to the "Issues" page- there should be a new issue with the "Symbols Missing" label:

Clicking into the Issue will show the trace and a message that the symbol file is missing. It can be uploaded by clicking the button highlighted below:

After this step, you will see the processed trace in the list of issues!


The Issue created when the symbol file is missing can now be set to resolved. It's good practice to always upload a symbol file before devices send any data.

Symbol files can also be uploaded from the Software → Symbol Files tab (follow this deep link to be brought to the symbol file upload point in the UI):

In addition to supporting decoding trace/coredump data, symbol files are also required for decoding Metrics.


You can programmatically upload symbol files with the Memfault CLI tool.

Symbol files should be uploaded to Memfault before devices send any data, to ensure all device data can be decoded.

Sending Data to the Memfault Cloud

If the project successfully builds, now we're ready to test the integration. If your board has console support, it's highly recommended to enable it for testing with the Memfault test commands:


# this board has a uart console

# enable logs as well

Flash an application with the console enabled and open a serial terminal to run the test commands:

uart:~$ mflt
mflt - Memfault Test Commands
clear_core :clear coredump collected
export :dump chunks collected by Memfault SDK using
get_core :check if coredump is stored and present
get_device_info :display device information
get_latest_release :checks to see if new ota payload is available
post_chunks :Post Memfault data to cloud
test :commands to verify memfault data collection
uart:~$ mflt test
test - commands to verify memfault data collection
assert :trigger memfault assert
busfault :trigger a busfault
hang :trigger a hang
hardfault :trigger a hang
memmanage :trigger a memory management fault
usagefault :trigger a usage fault
zassert :trigger a zephyr assert
reboot :trigger a reboot and record it using memfault
heartbeat :trigger an immediate capture of all heartbeat metrics
log_capture :trigger capture of current log buffer contents
logs :writes test logs to log buffer
trace :capture an example trace event

For example, run a crash example and dump Memfault chunks to the console output:

uart:~$ mflt test assert
*** Booting Zephyr OS build zephyr-v2.7.0 ***
[00:00:00.256,774] <inf> mflt: Reset Reason, RESETREAS=0x4
[00:00:00.256,805] <inf> mflt: Reset Causes:
[00:00:00.256,866] <inf> mflt: Software
[00:00:00.258,026] <inf> mflt: GNU Build ID: 6b8ccbd9d4e8653cda0b0f7e75fc8c467431f68e
[00:00:00.258,056] <inf> main: Memfault Demo App! Board nrf52840dk_nrf52840

[00:00:00.258,117] <inf> mflt: S/N: DEMOSERIAL
[00:00:00.258,148] <inf> mflt: SW type: zephyr-app
[00:00:00.258,209] <inf> mflt: SW version: 1.0.0-dev
[00:00:00.258,270] <inf> mflt: HW version: nrf52840dk_nrf52840

uart:~$ mflt export

The chunks can be pasted into the Integration Hub / Chunks Debug panel within the Memfault web application.

Troubleshooting Data Transfer

If you encounter any issues in your data transfer implementation, Memfault has tools to help debug!

  • To troubleshoot data not getting uploaded or processed correctly by the Memfault cloud, take a look at the Integration Hub → Processing Log view. This provides a filterable, chronological view of recent errors that have occurred while processing received data. See this documentation page for more information on the Integration Hub.
  • A view you can use toview the raw "Chunk" data payloadsthat have arrived for your project.
  • Precanned Data Payloads you can pass through your `user_transport_send_chunk_data()` implementation to test data transfer in isolation.
  • Server-side rate limiting will apply to the device you're using to work on the integration process. Once you can see the device on the Memfault Web App, consider enabling Server-Side Developer Mode for it on the Memfault Web App to temporarily bypass these limits.

Memfault Configuration

The Memfault SDK is configured in two places:

  1. The normal Kconfig interface- see options defined for the memfault-firmware-sdk module in one of the Kconfig interfaces, or check out the Kconfig file. These options apply to the Memfault Zephyr RTOS port contained within the Memfault SDK.

  2. The Memfault SDK configuration files, which contain configuration options for the SDK that are not Zephyr-specific. See the below files:

    • memfault_platform_config.h - See the default_config.h file in the Memfault SDK for documentation

    • memfault_metrics_heartbeat_config.def - See the docs page for using this file.

    • memfault_trace_reason_user_config.def - See the docs page for using this file


    Be sure the directory containing the configuration files is added to the Zephyr search directories:


    The Memfault SDK will silently ignore missing configuration files by default (see the CONFIG_MEMFAULT_USER_CONFIG_SILENT_FAIL Kconfig option, which when disabled will cause a build error if any configuration files are missing from the compiler search path).

Zephyr __ASSERT()

Zephyr RTOS has a built-in runtime assert system, see more information here:

Memfault's coredump capture routine will be triggered when the system encounters a failing __ASSERT(), however, by default, Zephyr asserts are disabled at build time. To enable them, set the CONFIG_ASSERT=y Kconfig variable:

# Memfault will record crashes due to Zephyr asserts. Enabling them means it's
# possible to root cause the problems on fielded devices 🎉 !

Reference Examples

Memfault provides two different Zephyr examples. See the links below for documentation and usage information.

  1. Zephyr example with networking enabled, targeting the STM32L4 Discovery Kit for IoT Node (B-L475E-IOT01A):

  2. Non-networked example, can be used with any Cortex-M board (default board is qemu_cortex_m3):