Conexio Stratus

A tiny, powerful, versatile cellular-IoT prototyping platform with out-of-the-box connectivity

Nov 09, 2021

Project update 2 of 11

Development progress and FAQs

by Rajeev Piyare

Hello friends, The first week of the campaign has been a thrill and we are happy to see so many of you supporting our campaign. We at Conexio @conexiotech are grateful for your support so far.

Throughout this campaign and beyond, we will post updates on the Conexio Stratus project so you can learn more about the hardware and its development process. For this first week’s update, we’ll be giving you a peek at our current progress and we’ll answer some frequently asked questions we have received via the technical question form.


We have received a number of excellent questions, summarized below:

Can I modify the Conexio Stratus example firmware and distribute it?

Yes! The firmware is released under the Apache License 2.0 and includes samples to get started with IoT development using the Stratus kit. The git repository can be found on GitHub: conexio-stratus-firmware.

Can I modify the Conexio Stratus hardware and produce my own?

Yes! The PCB hardware files are designed in Eagle CAD and will be released under the CERN Open Hardware Licence Version 2 - Weakly Reciprocal. See the CERN licenses page for more info.

How can I power the Stratus board?

The Stratus board can be powered from either the USB port, the LiPo battery, or a combination of USB + LiPo battery when charging the battery via the USB port. In addition, a solar panel can be used to recharge the LiPo battery connected to the Stratus kit.

How can I add cellular support to my external board with Conexio Stratus?

Conexio Stratus allows connecting peripherals via SPI, UART, or I2C. One can connect an external computer or MCU over UART to send AT commands to the cellular modem of the Stratus device, adding cellular connectivity to a new or existing IoT solution for prototyping purposes.

Do I need an external MCU with Conexio Stratus for executing Machine Learning?

No external MCU is needed! The Conexio Stratus combines a powerful ARM Cortex M33 with 1 MB of flash and 256 KB RAM. This gives Stratus the ability to execute machine learning models such as Tensor Flow Lite or models generated using Edge Impulse, right on the device.

We will also provide sample applications for getting started with ML using Edge Impulse platform in our git repository. Stay tuned!

Can I only use the MCU of Conexio Stratus without the cellular modem?

Yes! If your application does not use the cellular modem or call the modem APIs, it will remain disabled in the firmware. One can also explicitly disable it in the project configurations.

Which wireless standards are used by the Conexio Stratus kit?

Conexio Stratus connects to the cloud over LTE-M, NB-IoT, and Cat-1 networks.

How much-prepaid data is available with Conexio Stratus?

Conexio Stratus comes with 500 MB of data and 250 SMS that is valid for a period of ten years. Whether you use up the quota in a month or a year is up to you and your application. We will allow Stratus users to top-up or buy more cellular data through us.

What type of external GPS antenna do I need for the Stratus?

For accessing GPS, Stratus relies on an active GPS antenna connected to its U.FL antenna port.

Does the Conexio Stratus provide a built-in way to measure temperature, shock/impact, voltage, and/or cellular signal strength data, and send it to the cloud?

The Conexio Stratus includes onboard SHT40 temperature and humidity sensors, as well as LIS2DH accelerometer sensors that are accessible via the sensor API. The easiest way to learn how to access sensor data from an SHT40 or LIS2DH is by following one of the Stratus sensor applications.

Modem voltage information can be captured by querying the nRF9160 modem API while the Zephyr ADC infrastructure can be used to measure the voltage of the device power supply.

Shock/impact detection can be reported by enabling the built-in accelerometer sensor, then querying it to enhance your data with “shock/impact” information. In addition, cellular signal strength data will be fetched using the modem API.

Does the Conexio Stratus provide a way to perform cellular tower triangulation to get a location?

Yes! We will provide a multi-cell location sample application to get a device’s position based on LTE cell measurements. This allows continuous tracking of the device’s location for asset tracking applications without wasting a lot of power and draining the battery.

Routing and Transferring Data

The Conexio Stratus supports routing of IoT data to AWS, Microsoft Azure, nRF Cloud, Datacake, and any other cloud services that support MQTT, HTTPS, or TCP data transfer protocol.

Documentation and Getting Started

We have also been busy crafting the full documentation and ‘getting started’ guidelines for the Conexio Stratus. It’s still a work-in-progress, as we want to capture and document all the steps required to start building IoT applications with Stratus so that setup will be a breeze for our backers.

In addition, we are creating more sample applications for the Stratus kit and testing our prototypes. Our objective with these tests is to improve our firmware libraries, provide more use case examples, and make sure everything works as expected. You may also notice we have started to populate the conexio-stratus-firmware repo.

All the walk-through tutorials will be posted on our tutorial blog. Our early tutorial featuring Conexio Stratus has also been published on the ZephyrProject website.

Hardware Development

Conexio boards

Besides the work on Conexio Stratus’s software, we are also working on a few other ideas for improvements on the hardware side. This involves selecting and choosing components with ultra-low-power quiescent current, reducing the device’s power consumption even further.

Additionally, we are verifying all the hardware functionality and operation to make sure the product’s operation and usage is as user-friendly as possible.

It is important for us to engage with our audience, so we are always excited to hear from you and listen to your feedback and suggestions. You are very welcome to join us on our Conexio Discord channel or on Twitter @conexiotech. Stay tuned and we will keep you posted on our latest news and progress.

Thank you for everything so far, and please help us fully fund this project by spreading the word!

Thank you from Team Conexio!

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