Cellabox went open source to help to tackle air quality issues. We decided to publish the hardware design and the source code on Github.
This blog is about why we did this and how you can get started with Cellabox, OpenThread and air quality sensors.
Some facts about Cellabox:
The idea behind Cellabox is to provide low-cost wireless air quality sensors with the maximum possible accuracy in the <$100.- price range. This would bring air quality sensors to the mass and everybody could benefit: "Better Air Quality Through Better Data".
Ultra-low power: no need to replace batteries in years.
Solar energy harvesting: outdoor module (e.g. PM2.5)
Controller: Nordic nRF52840
Wireless: OpenThread (IEEE 802.15.4, CoAP, IPv6)
Cloud Platform: thethings.iO
Why open source?
As the funding was and still is very very limited, we saw open source as the biggest chance to have an impact on the world's air quality and people's health. This is what we personally wanted to achieve.
In case you would like to support us, click on one of the following links. THANK YOU!
Who can contribute?
Do you share our vision and want to contribute to Cellabox? Cellabox published the source code under the license of Berkeley Software Distribution (BSD-3). This means that everybody can contribute to the code and you can even copy the code and use it in our own product (as long as the copyright text retains, more details here).
How to get started?
Buy at least two nRF52840 Preview DK and follow the instructions of Nordic on how to setup a Thread network (you will need a RapbarryPi 3 B for the border router).
Connect the sensor of your choice to the development kit according to the pinout and the various schematics:
Download the source code and follow the instructions on how to setup your Eclipse environment. Your are done and ready to run your own air quality sensor module :-)
Here an example of an Indoor Air Quality (IAQ) breadboard:
What is the technology behind Cellabox?
The wireless technology which the Cellaboxes use, is the same protocol which is used by Google (Nest): see OpenThread and Nest.
Cellaboxes have no display. Sensor data are stored in the cloud and you can view current and preceding sensor data e.g. on your smartphone or your tablet or your notebook. You just need a browser (Chrome, Safari, Edge, Firefox, Internet Explorer, ...). Here an example of VOC (indoor air quality) sensor data in our office:
Why using OpenThread (IEEE 802.15.4) and not e.g. Bluetooth? Easy enough to answer this:
IPv6/CoAP: OpenThread uses natively IPv6 and CoAP. This is essential for the REAL Internet-of-Things (IoT). The IoT of the future runs on CoAP. CoAP is open and standardized by the IETF.
Reliability: no single-point of failure. Thread even supports multiple border routers!
Security/commissioning: add new devices to your personal Thread network is easy (smartphone app) and secure (you must have the device in our own hands, where e.g. the barcode of the TOKEN sticks).
Why Nordic nRF52840?
We are huge fans of Nordic, because:
Nordic has one of the best forums we have ever seen, where you get quick response from real experts and Nordic employees. This helps a lot during development.
Sensirion is one of the best low-power sensor companies world-wide. Sensirion delivers a very robust and thoroughly tested sensor technology and their recently launched gas sensors (SGP) are ahead when it comes to low-power VOC sensors on semiconductor basis.
Another good thing is, that you get excellent support from their field application engineers!
Why SPEC Sensors?
SPEC Sensors delivers a wide range of electrochemical sensors:
Nitrogen Dioxide (NO2)
Sulfur Dioxide (SO2)
Carbon Monoxide (CO)
Hydrogen Sulfide (H2S)
These sensors are ultra-low power, which enables the Cellaboxes to run for years and years to come. Furthermore, SPEC Sensors delivers sensors with an excellent accuracy to price ratio and an expected lifetime of up to 10 years.
We first started with IBM Watson IoT (IBM Cloud). However, once we got more and more towards CoAP, we switched the cloud platform. After some research, thethings.iO from Barcelona was chosen because:
It supports CoAP (unfortunately no DTLS yet)
Easy to setup a panel with sensor data
You can find code examples by Nordic Semiconductors for sending data over OpenThread to thethings.iO
Become a Sponsor
Do you share our vision of low-cost and open source air quality sensors? If you want to become a sponsor of Cellabox and help in ways such as work with other companies to deliver hardware kits, please click here. For donations click here.
We will try our best and give you support via email: firstname.lastname@example.org.
We hope there will soon be a clever and smart community which supports each other with answers about setting up the build environment or solving air quality measurement problems!
Last but not least, I want to say THANK you to SiLAB for their valuable support and the opportunity to work with them in the same office. It is always an enrichment to spend time with you guys.
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