Batteryless Cellular IoT with Conexio Stratus nRF9151/nRF9161

Overview

The Batteryless Cellular IoT with Conexio Stratus nRF9151/nRF9161 firmware is based on Golioth Device Management and Data Routing template that uses nRF Connect SDK. The application connects to Golioth, streams time-series data, senor readings, and cellular based location tracking to the Golioth cloud. From the Golioth web console you may deploy OTA firmware updates, adjust device Settings, and issue Remote Procedure Calls (RPCs). It is set up as a standalone repository, with all Golioth features implemented in basic form.

Requirements

• nRF Connect SDK version 2.9.0 installed
• Golioth SDK pre-installed for NCS v2.9.0
• Golioth account and credentials
• Network connectivity

Hardware and Components

• Conexio Stratus Pro nRF9151 or nRF9161
• Super capacitor, LIB1620Q4R0407, 4V, 400F
• Rakwireless Unify Enclosure with solar panel
• LTE antenna

System Overview Block Diagram

Internal electronics

Fully assembled system

Installing the nRF Connect SDK v2.9.0

• Download and install a cross-platform tool nRF Connect for Desktop for your operating system.
• Install and run the nRF Connect tool on your machine.
• Click Install next to the Toolchain manager.
• Once the Toolchain manager is installed, click open.
• Select nRF Connect SDK v2.9.0 and click Install. Depending on your internet speed, it may take a few tens of minutes, so go and grab yourself a cup of coffee ☕
• Once the installation is complete, click the dropdown menu and hit Open Terminal.
• This will open the terminal in the installed directory of the nRF Connect SDK as indicated. Hooray🎉 . You have successfully installed the NCS.
• For more info, refer to this documentation.

Installing the Golioth Firmware SDK v0.17.0

Adding the Golioth Firmware SDK to an existing nRF Connect SDK based projects

Add the following entry to the ncs/v2.9.0/nrf/west.yml file of an existing West based project:

Note

To ensure that default Kconfig values are propagated correctly, place the golioth entry first in your west manifest after the following piece of code.

# NCS repositories.
#
# Some of these are also Zephyr modules which have NCS-specific
# changes.
# Golioth repository.
- name: golioth
  path: modules/lib/golioth-firmware-sdk
  revision: v0.17.0
  url: https://github.com/golioth/golioth-firmware-sdk.git
  submodules: true
- name: zephyr-network-info
  path: modules/lib/network-info
  revision: v1.2.1
  url: https://github.com/golioth/zephyr-network-info

and clone all repositories by running:

west update

• zephyr-network-info is a helper library for querying, formatting, and returning network connection information via Zephyr log or Golioth RPC

Project Configuration for Low Power Mode and Sensor Sampling

In the prj.conf update the following configurations as per project requirements.

Note

Smaller intervals mean faster sampling and more frequent data transmission to the cloud cloud. Handy for testing purposes but not for final deployment due to higher power consumption.

# How often to sample and send environmental sensor data
CONFIG_SENSOR_SAMPLE_INTERVAL_SECONDS=3600

# How often to fetch cellular location data
CONFIG_LOCATION_TRACKING_SAMPLE_INTERVAL_SECONDS=7200

If you want to view the serial logs, then in the overlay_low_power.conf, enable serial logging by adding y to the following configs:

# Enable/disable serial logging
CONFIG_SERIAL=y
CONFIG_LOG=y
CONFIG_UART_CONSOLE=y
CONFIG_NET_SHELL=y

Note

In production/deployment firmware all the serial logging should be disabled to put the device properly in low-power mode.

Compiling the application using nRF Connect Extension

Prior to compiling the application, we first need to generate the device build configuration for the project by clicking on the Add Build Configuration option.

This opens a new tab, asking the user to select the board for which the build configurations will be generated. In our case, we will

1. Check the Custom under the Board target option.
2. Then from the drop-down menu select the Board target as:

conexio_stratus_pro/nrf9151/ns

or

conexio_stratus_pro/nrf9161/ns

3. Under Extra Kconfig fragments options, browse and select overlay_low_power.conf.
4. Next, under Extra Devicetree overlays, browse and select respective board overlays conexio_stratus_pro_nrf9151_ns.overlay or conexio_stratus_pro_nrf9161_ns.overlay.
5. To generate the app_update.bin, select No sysbuild under System build (sysbuild) option.
6. Cick Build Configuration to start the Zephyr application build process.

• If any issues see the Conexio device documentation for detailed instructions on how to build the application.

Flashing and Running the Sample Application on the Device

Setting DFU Mode (Device Firmware Upgrade)

To program the device via USB, you will need to put the device into DFU (Device Firmware Upgrade) mode first. This mode triggers the onboard bootloader that accepts firmware binary files. To enter DFU mode:

1. Hold down Mode button : labeled BUTTON
2. Press and release Reset button : RESET
3. Release only the RESET button, while holding down the MODE button
4. Wait for the white LED to turn on (steady-state)
5. Release the MODE button
6. The device is now in DFU mode. 🚨

Flashing an application via USB using newtmgr

To upload the firmware, we now have to:

• Open the terminal within the nRF Connect extension and invoke the

newtmgr -c serial image upload build/zephyr/app_update.bin 

making sure the device remains in DFU mode.

Authentication specific configuration for Device Onboarding

To enable a new device so that it can connect securely to the Golioth cloud,

1. Build the firmware with serial logging enabled.

# Enableserial logging
CONFIG_SERIAL=y
CONFIG_LOG=y
CONFIG_UART_CONSOLE=y
CONFIG_NET_SHELL=y

2. Upload the firmware to the device.
3. Reset the device.
4. Configure PSK-ID and PSK using the device shell as shown below based on your Golioth project credentials and reboot:

uart:~$ settings set golioth/psk-id <my-psk-id@my-project>
uart:~$ settings set golioth/psk <my-psk>
uart:~$ kernel reboot cold

Adding Pipeline to Golioth

Golioth uses Pipelines to route stream data. This gives you flexibility to change your data routing without requiring updated device firmware.

Whenever sending stream data, you must enable a pipeline in your Golioth project to configure how that data is handled. Add the contents of pipelines/cbor-to-lightdb.yml as a new pipeline as follows (note that this is the default pipeline for new projects and may already be present):

1. Navigate to your project on the Golioth web console.
2. Select Pipelines from the left sidebar and click the Create button.
3. Give your new pipeline a name and paste the pipeline configuration into the editor.
4. Click the toggle in the bottom right to enable the pipeline and then click Create.

All data streamed to Golioth in CBOR format will now be routed to LightDB Stream and may be viewed using the web console. You may change this behavior at any time without updating firmware simply by editing this pipeline entry.

Have Questions?

Note

This repository serves as a reference template for building battery-free cellular IoT systems using Conexio hardware as a proof-of-concept. The codebase is actively being developed and is intended to serve as a starting point for your own application-specific implementation. It may not be production-ready and is expected to evolve as features are added and optimized.

If you have questions, feedback, or need guidance on adapting this template for your project:

• Contact the Conexio engineering team at [email protected]
• For Golioth-specific cloud integration questions, please contact the Golioth team or post in the Golioth Community Forum.

Copyright (c) 2025 Conexio Technologies, Inc.