nordic-wifi-memfault sample

A comprehensive Memfault integration reference for Nordic Wi-Fi platforms, demonstrating IoT device observability with Wi-Fi connectivity, Wi-Fi provisioning over BLE, HTTPS/MQTT communication, and Memfault cloud-based crash reporting, metrics, and OTA updates.

Platform Support

Board	Host MCU	Wi-Fi	BLE	Status
nRF7002DK	nRF5340 (dual-core)	nRF7002	Network core (hci_ipc)	✅ Supported
nRF54LM20DK + nRF7002 EBII	nRF54LM20 (single-core)	nRF7002 via EB II shield	SoftDevice Controller (same core)	✅ Supported
nRF7120DK	nRF7120 (integrated)	nRF7120	—	🔜 Planned

All platform-specific build targets, overlays, and partition maps live under board-named files. The application core (modules, Memfault integration) is shared across all boards.

Overview

• SDK: nRF Connect SDK v3.2.4 (workspace application)
• Memfault SDK: bundled with NCS v3.2.4

Key Features

Memfault Device Observability

• ✅ Crash Reporting — Automatic coredump capture (internal flash / RRAM) and upload to Memfault dashboard
• ✅ OTA Updates — Secure MCUboot-based firmware updates deployed via Memfault cloud
• ✅ Metrics & Heartbeats — WiFi signal, channel, AP vendor, stack headroom, heap usage, HTTP/MQTT counters
• ✅ Heap Monitor — Auto-tracks system heap and dedicated mbedTLS heap; feeds live values into Memfault metrics
• ✅ nRF70 Diagnostics CDR — PHY/LMAC/UMAC firmware statistics uploaded as Custom Data Recordings

Connectivity & Provisioning

• ✅ Wi-Fi Connectivity — WPA2/WPA3 with automatic reconnection and NVS credential persistence
• ✅ WiFi Provisioning over BLE — Credential configuration via the nRF Wi-Fi Provisioner mobile app
• ✅ HTTPS Client — Periodic TLS HEAD requests to example.com with success/failure metrics
• ✅ MQTT Client — TLS-secured echo test to broker.emqx.io with success/failure metrics

Platform

• ✅ Dual Hardware — nRF7002DK (nRF5340 dual-core) and nRF54LM20DK + nRF7002EB II (nRF54LM20A single-core)
• ✅ MCUboot Bootloader — Dual-bank updates with rollback protection, external-flash OTA slot

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Quick Start

1. Set Memfault project key

cp overlay-app-memfault-project-info.conf.template overlay-app-memfault-project-info.conf
# Edit the file and set CONFIG_MEMFAULT_NCS_PROJECT_KEY

2. Build and flash

nRF7002DK:

west build -b nrf7002dk/nrf5340/cpuapp -p -- \
  -DEXTRA_CONF_FILE="overlay-app-memfault-project-info.conf"
west flash --erase

nRF54LM20DK + nRF7002EB II:

west build -b nrf54lm20dk/nrf54lm20a/cpuapp -p -- \
  -DSHIELD=nrf7002eb2 \
  -DEXTRA_CONF_FILE="overlay-app-memfault-project-info.conf"
west flash --recover

3. Provision WiFi

Use the nRF Wi-Fi Provisioner app: Android | iOS

• Connect to device named PV<MAC> (e.g., PV00D318)
• Select your network and enter the password
• The device connects and saves credentials to NVS — they persist across reboots

4. Monitor via UART

Board	Port	Baud
nRF7002DK	VCOM1 (/dev/tty.usbmodem*3)	115200
nRF54LM20DK	VCOM0 (/dev/tty.usbmodem*1)	115200

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Button Controls

The application uses the first two logical buttons (DK_BTN1 / DK_BTN2).
Their physical labels differ by board:

nRF7002DK label	nRF54LM20DK label	Press	Action
Button 1	BUTTON 0	Short (< 3 s)	Trigger Memfault heartbeat + nRF70 stats CDR upload
Button 1	BUTTON 0	Long (≥ 3 s)	Stack overflow crash (test crash reporting)
Button 2	BUTTON 1	Short (< 3 s)	Check for OTA update
Button 2	BUTTON 1	Long (≥ 3 s)	Division by zero crash (test fault handler)

On the nRF54LM20DK PCB the buttons are silk-printed BUTTON 0 – BUTTON 3.
DK_BTN1 maps to BUTTON 0 and DK_BTN2 maps to BUTTON 1 (both are sw0/sw1 in the board DTS).
BUTTON 2 and BUTTON 3 are not used by this application.

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Project Structure

nordic-wifi-memfault/
├── west.yml                                    # Workspace manifest (NCS v3.2.4)
├── CMakeLists.txt
├── Kconfig
├── prj.conf                                    # Shared config for all boards
├── boards/
│   ├── nrf7002dk_nrf5340_cpuapp.overlay        # nRF7002DK DTS overlay
│   ├── nrf54lm20dk_nrf54lm20a_cpuapp.conf      # nRF54LM20DK Kconfig overrides
│   └── nrf54lm20dk_nrf54lm20a_cpuapp.overlay   # nRF54LM20DK DTS overlay
├── pm_static_nrf7002dk_nrf5340_cpuapp.yml      # nRF7002DK partition map
├── pm_static_nrf54lm20dk_nrf54lm20a_cpuapp.yml # nRF54LM20DK partition map
├── sysbuild/                                   # MCUboot, hci_ipc per-board config
├── src/
│   ├── main.c                                  # Banner + sleep (modules init via SYS_INIT)
│   └── modules/
│       ├── messages.h                          # Zbus channel message types
│       ├── button/                             # Button SMF, BUTTON_CHAN
│       ├── network/                            # WiFi/network events, WIFI_CHAN
│       ├── heap_monitor/                       # System + mbedTLS heap monitor
│       ├── wifi_prov_over_ble/                 # BLE WiFi provisioning
│       ├── app_memfault/                       # Memfault: upload, metrics, OTA, CDR
│       ├── app_https_client/                   # Periodic HTTPS HEAD to example.com
│       └── app_mqtt_client/                    # TLS MQTT echo test
├── overlay-app-memfault-project-info.conf      # Memfault key (git-ignored, from template)
└── overlay-app-memfault-project-info.conf.template

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Flash Memory Layout

nRF7002DK (nRF5340 — 1 MB internal flash)

┌─────────────────────────────────────────────┐
│  0x00000  mcuboot          40 KB  (0x0A000) │ Bootloader
│  0x0A000  mcuboot_pad     512 B   (0x00200) │ Image header
│  0x0A200  app             ~912 KB (0xE3E00) │ Main application
│  0xEE000  settings_storage  8 KB  (0x02000) │ WiFi credentials / NVS
│  0xF0000  memfault_storage 64 KB  (0x10000) │ Crash coredumps
│  0x100000 ── end of internal flash ─────────│
└─────────────────────────────────────────────┘

External flash — MX25R64 (8 MB):
┌─────────────────────────────────────────────┐
│  0x000000  mcuboot_secondary  912 KB        │ OTA update slot
│  0x0E4000  external_flash    ~7.1 MB        │ Reserved
└─────────────────────────────────────────────┘

nRF54LM20DK (nRF54LM20A — 1984 KB RRAM)

┌─────────────────────────────────────────────────┐
│  0x000000  mcuboot            56 KB (0x0E000)   │ Bootloader
│  0x00E000  mcuboot_pad         2 KB (0x00800)   │ Image header
│  0x00E800  app              1906 KB (0x1DC800)  │ Main application
│  0x1EB000  settings_storage    8 KB (0x02000)   │ WiFi credentials / NVS
│  0x1ED000  memfault_storage   64 KB (0x10000)   │ Crash coredumps
│  0x1FD000 ── end of flash_primary ──────────────│
└─────────────────────────────────────────────────┘

External flash — MX25R6435F (8 MB via spi00):
┌─────────────────────────────────────────────────┐
│  0x000000  mcuboot_secondary 1908 KB (0x1DD000) │ OTA slot (= primary size)
│  0x1DD000  external_flash   ~6.1 MB (0x623000)  │ Reserved
└─────────────────────────────────────────────────┘

memfault_storage must be in internal flash (RRAM/NOR) for power-fail safety and boot-time access before the external flash driver initialises.

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Architecture Notes

nRF7002DK vs nRF54LM20DK

Aspect	nRF7002DK	nRF54LM20DK + nRF7002EB II
Host SoC	nRF5340 (dual-core)	nRF54LM20A (single-core)
BLE host	Network core (hci_ipc image)	SoftDevice Controller on App core
WiFi chip	nRF7002 (on-board)	nRF7002 via nRF7002EB II shield (SPI spi22)
SR Coex RF switch	✅ Yes	❌ Not wired on EB II
Internal flash	1 MB NOR	2 MB RRAM
External flash	MX25R64 (SPI)	MX25R6435F (spi00)
App slot	~912 KB	1906 KB
SRAM	448 KB app + 64 KB IPC	511 KB (full)
UART console	VCOM1 (uart0)	VCOM0 (uart30, routed via EB II)

Single-core BLE + WiFi (nRF54LM20DK)

The nRF54LM20A has no network core. Both the BLE SoftDevice Controller and the nRF70 WiFi driver run on the Application core. During WiFi provisioning over BLE, both stacks share the BT RX workqueue thread — hence CONFIG_BT_RX_STACK_SIZE=22000 (set by the wifi_prov_over_ble module defaults).

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Memfault Integration

Device Onboarding

1. Upload symbol file after building:

   • nRF7002DK: build/memfault-nrf7002dk/zephyr/zephyr.elf
   • nRF54LM20DK: build_nrf54lm20dk_wifi/nordic-wifi-memfault/zephyr/zephyr.elf
   • Dashboard → Fleet → Symbol Files → Upload

2. Set firmware version in prj.conf:

   CONFIG_MEMFAULT_NCS_FW_VERSION="1.0.0"

Collected Metrics

Metric	Type	Description
wifi_rssi	Gauge	Signal strength (dBm)
wifi_sta_*	Gauge	Channel, beacon interval, DTIM, TWT
wifi_ap_oui_vendor	String	AP vendor (Cisco, Apple, ASUS, etc.)
ncs_system_heap_*	Gauge	System heap total, current, peak
ncs_mbedtls_heap_*	Gauge	mbedTLS heap total, current, peak
stack_free_*	Gauge	Per-thread stack headroom
app_https_req_total_count	Counter	Total HTTPS requests
app_https_req_fail_count	Counter	Failed HTTPS requests
app_mqtt_echo_total_count	Counter	Total MQTT echo attempts
app_mqtt_echo_fail_count	Counter	Failed MQTT echoes

OTA Updates

1. Update version in prj.conf:

   CONFIG_MEMFAULT_NCS_FW_VERSION="2.0.0"

2. Build and upload zephyr.elf (symbols) + dfu_application.zip (OTA payload) to Memfault dashboard.
3. The device checks for updates on WiFi connect and on Button 2 short-press.

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Using Pre-built Release Firmware

Download the latest firmware from the Releases page.
Each release publishes 6 files per Memfault project (nord_project / terr_project) — 3 per hardware target:

File naming

<project>_<version>_<board>_<type>

Suffix	Description
*_nrf7002dk_zephyr.elf	Debug symbol file for nRF7002DK
*_nrf7002dk_zephyr.signed.bin	OTA image for nRF7002DK
*_nrf7002dk_full.hex	Full flash image for nRF7002DK (CPUAPP + CPUNET merged)
*_nrf54lm20dk_zephyr.elf	Debug symbol file for nRF54LM20DK
*_nrf54lm20dk_zephyr.signed.bin	OTA image for nRF54LM20DK
*_nrf54lm20dk_full.hex	Full flash image for nRF54LM20DK (MCUboot + app merged)

Initial programming (first time)

nRF7002DK — erase and program all cores in one step:

nrfutil device program --firmware <project>_<ver>_nrf7002dk_full.hex --core All --erase-all

Or using nRF Programmer: select the _nrf7002dk_full.hex file, enable Erase all, click Program.

nRF54LM20DK + nRF7002EB II — RRAMC requires recovery to unlock protected MCUboot regions:

nrfutil device program --firmware <project>_<ver>_nrf54lm20dk_full.hex --recover

OTA updates (subsequent updates via Memfault)

1. Upload *_zephyr.elf to Memfault → Software → Symbol Files so the dashboard can decode stack traces and coredumps.
2. Upload *_zephyr.signed.bin to Memfault → Software → OTA Releases and activate the release.
3. The device polls for and downloads the update automatically on Wi-Fi connect or when Button 2 / BUTTON 1 is short-pressed.

Choosing a project file

File prefix	Memfault project	Use for
nord_project_*	Nord project	Nord devices
terr_project_*	Terr project	Terr devices

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License

This project is licensed under the LicenseRef-Nordic-5-Clause license. See the LICENSE file for details.

🤝 Contributing

Contributions are welcome! Please ensure all code follows the Zephyr coding style and includes appropriate license headers.

📞 Support

For questions and support:

• Nordic DevZone
• GitHub Issues