By Cato Fagermo, NeoCortec
Background
In measuring something in a building – whether it is an Indoor Air Quality (IAQ) or occupancy, or if you want to control something e.g. such as smart thermostatic valves, you need to be able to communicate data between those devices and a controller/gateway. However, this is not as easy as it may sound for large buildings such as commercial buildings, multifamily homes, hospitals, industrial buildings and other large buildings. Measuring the data is easy – there are a lot of sensors on the market. Getting that data delivered into the building management systems (BMS), a gateway or controller or into the cloud is however not that easy. If you are building a new building it is easy – you will install a cabled field bus such as e.g. ModBus, BACnet or KNX. But if you have an old building, without a cabled field bus, you will have a hard time convincing a building owner to do that cabling unless they plan for a major renovation of the building. The cost of installing the field bus and the inconvenience for the users / tenants of the building is simply too high. The business case is difficult to see.
It is obvious to go for a wireless solution, and there are alot of them. Examples are Zigbee / Thread, BLE and LoRaWAN, as well as many more. Common to most of them is that these are shifting the challenge from one set of challenges to another. Yes, you can install sensors using these wireless solutions, in a building and you can make it work. However, most of these buildings are too large for these technologies to work without installing many infrastructure devices such as repeaters or gateways throughout the building. Without these, you risk having sensors with poor or no connection. These infrastructure devices require cables. For sure mains power, but also a field bus depending on implementation. So, we are back to cabling the building, except that now the cables do not have to go into all the rooms in the building.
An often overseen challenge is that buildings are dynamic. As tenants move in and out will the buildings have to adapt. Buildings will be changed or remodeled, walls raised or removed. As these changes happen over years, it is more likely than not that mistakes will happen, disconnecting the infrastructure devices thus consequently also disconnecting parts of the sensors.
NeoMesh is another solution designed for devices which can operate for years using simple AA batteries. NeoMesh is scalable to thousands of devices in the same network. As the devices are organized in a mesh network, they will communicate through each other without repeaters needed, and the network can be scaled to cover almost any size building.
Embedded World 2024
NürnbergMesse GmbH is a large exhibition ground in Nuremberg, Germany. Each year the exhibition Embedded World is organized with NeoCortec as one out of over 1,100 exhibitors. As a part of the display for the 2024 exhibition, we were showcasing a full IOT solution based on NeoMesh. The purpose is to show how easy it can be to build sensors and to communicate data generated by those to an IOT platform for further processing.
Embedded World 2024 demo
For the Embedded World, we decided that we wanted to measure IAQ data: temperature, humidity and carbon dioxide (CO2) level. In addition, we wanted to count the number of Bluetooth devices which were near each node, in order to provide an estimate of concentration of people across the area and throughout the day. We wanted to make a fully battery-operated network, so that installation and uninstallation could be done in just a few hours.
The nodes were made by Clickboards from MikroElektronika. For each node, three Clickboards were combined and mounted on a development board together with a battery.
The devices were specified, assembled and programmed by a 2nd year Danish Technical University (DTU) student. The IAQ sensor was a Sensirion sensor assembled on a Clickboard and sampled by the Nordic microcontroller (nRF) onboard the BLE 10 Click. The same BLE 10 Click was used for scanning for Bluetooth beacons nearby, using the nRF embedded 2.4 GHz radio. A small program was written for the nRF for sampling the data. For the scanning of Bluetooth devices nearby, the purpose was to make a relative estimate on how many people there were nearby the node. To take into account stationary Bluetooth devices as well as exhibitor personal, were beacons that had been visible for more than 10 minutes subtracted.
The nodes were hung up at 35 locations in halls 3 and 3A at Embedded World. Worth nothing is that both halls have walls made out of metals. This makes radio communication through the walls exceedingly difficult as the halls function as Faraday cages. To show the flexibility of a mesh topology, some nodes were positioned outside of the halls near the doors. See floorplan below (fig 2).
As a gateway was a BeaglePlay board from BeagleBoard.org Foundation used, equipped with a NeoMesh Clickboard. The open source NeoMesh gateway software was installed, exposing two IP sockets where JSON formatted packages can be sent into or out of the mesh network. The data was then, using Node-RED, uploaded to Avnet Abacus’ IOT Connect cloud platform. Dashboards for visualization of the IAQ data as well as Bluetooth beacon heatmap were then developed.
In addition, was the NeoMesh monitoring tool installed on the gateway. This tool provides a visualization of the mesh network, showing which nodes were connected to each other and flagging of any problematic nodes.
Results
The results can be summarized into three categories:
Ease of developing: The MikroE Clickboards together with the BeaglePlay board provide a flexible platform for quick and easy manufacturing of nodes. The high number of Clickboards available provides a high level of flexibility in combining microprocessor-, sensor- and communication boards to build a wide range of devices. By downloading libraries for each Clickboard, can the application software be made with a minimum of coding needed. This makes the time and cost for developing a proof of concept very low.
Ease of installing and establishing a network: The agreement with the event organizer was to use available “public” locations not being a part of other exhibitors stands. This made it impossible in advance to plan the location for the nodes. Instead, their positions were identified by walking around in the halls. The nodes were adhered to columns and walls using self-adhesive tape, and then switched on. As all nodes were battery powered, no mains power was needed. The NeoMesh protocol ensured that once switched on, the nodes would automatically be included in the network.
As the two halls were separated from each other and each had metal walls, did we expect that it could be challenging to get communication between the halls. If this was the case, then two islands would form. To mitigate this extra nodes were installed around the two passages between the halls, to create a link between them. Similar was done to those nodes located in the foyers outside of hall 3.
As can be seen from figure 2, this was sufficient to create a good connection between the halls. However, what we also saw was that at night when the passage doors were shut, we did indeed lose connectivity between the two halls.
Data acquisition: IAQ data and people counter: Temperature, humidity and CO2 data were collected every 2 minutes from the sensors. As expected, we could see a steady increase in CO2 around noon which was in line with our perception of this being the busiest time of the day. The CO2 value was peaking at around 1000-1100 ppm, unlike other exhibitions we have been to where we could see CO2 values op of up to 1500 ppm during the peak of the day. 1500 ppm is getting close to levels where the air quality is considered unhealthy. At evening and night, we could see CO2 fall to outdoor levels.
Whereas the people counting was never meant to represent an accurate estimate of people, as many people wear more than one Bluetooth device and some wear none. But we could see, just as expected, that during the morning there was a higher density of people near the entrance doors. Throughout the day this got more uniform with people spreading out. With some refinement this could be an effective way, on a simple basis, to build a heatmap of people and an approximation of how many people were there.
Conclusion
NeoCortec has together with Avnet and MikroE made a sensor network of clickable modules, without any hardware developed. Installing these at Messe Nürnberg was very easy as they run on batteries at can be mounted exactly where you want them to be. When switched on in an arbitrary sequence, will the network form itself.
The pop-up application installation was made to measure IAQ and create an approximation of where visitors were distributed in the two halls. Whereas the purpose of the test was not to create a qualitative analysis of the air quality, did it confirmed the quality of the air was acceptable throughout all exhibition dates, also at hours when the number of visitors peaked. and even more so that the distributed sensor network
About NeoMesh
At NeoCortec, we make NeoMesh. NeoMesh is a wireless communication protocol to be embedded in smart devices to enable communication between the devices as well as to the cloud. NeoMesh is built completely from scratch to overcome some of the limitations found in e.g. Zigbee, Zwave, Bluetooth, Thread and others: Scalability in number of devices and range while low at power consumption.
At NeoCortec, we aim towards making non-smart and large buildings smarter by using NeoMesh. Easy upgrade without cabling.
We do not make sensors, we do not measure IAQ or count people. But we enable those – and other modes of sensing – through collecting data. NeoMesh is available on communication modules as well as on a license basis on various chipsets.
