Use case, collect data from multiple sensors in a room

RE: Use case, collect data from multiple sensors in a room

Bonadio — Thu, 07 May 2020 18:26:00 GMT

Thanks, we ordered some devices so we can start doing some prototyping

RE: Use case, collect data from multiple sensors in a room

haakonsh — Thu, 07 May 2020 07:12:48 GMT

If you can limit the maximum to 56 you can have a peripheral connection from two of the centrals to the third Central, where they offload their data to it. Then you only need to extract data from the third Central.

RE: Use case, collect data from multiple sensors in a room

Bonadio — Tue, 05 May 2020 15:29:23 GMT

Hi Haakonsh

Thanks for the suggestion.

The maximum would be around 60 boxes and they could stay from 1 hour to 24h. So the idea of 3 central with constant connection is a good option too.

To send the data to our dashboard we are thinking on the central to connect to some other mcu with wifi and send the data using MQTT feeding our dashboard, from there we can manage the alarms.

[]s

RE: Use case, collect data from multiple sensors in a room

Bonadio — Tue, 05 May 2020 15:18:15 GMT

Thanks Dmitry, yes security is not a problem

RE: Use case, collect data from multiple sensors in a room

haakonsh — Tue, 05 May 2020 09:48:31 GMT

That'll work, but you'll have no control over this requirement:

[quote user=""]Each box must have its temperature checked no longer than 3 minutes.[/quote]

RE: Use case, collect data from multiple sensors in a room

haakonsh — Tue, 05 May 2020 08:16:27 GMT

What is the maximum number of boxes that will be in the room? For how long will they be there?

I think the most robust solution will be 3 central devices with a constant connection to 1/3 of the devices each. By using a connection interval of 15 seconds you will save a lot of power on the peripherals as they won't have to re-establish a connection every time they need to send an update, and it will be robust with re-transmissions and channel hopping. A central based on the nRF52832 or 52840 can handle 20 peripherals each, so 3 centrals can handle 60 peripherals.

What was your plan in getting the information off the central device, or what is your plan for the next steps of the data gathering, where does the data end up?

RE: Use case, collect data from multiple sensors in a room

Dmitry — Tue, 05 May 2020 08:07:39 GMT

Hi,

If you're not concerned about security, I think the best way is to use connectionless mode - put temperature data directly into an advertising packet. In this case you're not limited with 20 simultaneous connections, and there is no overhead with establishing a connection every time.