Need advice on making a nrf52840 powered water leak detector

[olalonde]

I'm trying to build a simple water leak detection system. The sensor would need to alert a user through SMS/mobile notification when a leak is detected.

I was thinking of building the sensor with a nrf52840 microcontroller and have it send leak alerts via BLE when a leak is detected.

That being said, the leak detection should work even when the user is not at home. So I believe this will require building a hub to bridge the BLE data to the cloud (e.g. a "BLE gateway")?

Could the device instead publish the data directly to a server via Thread and a Thread Border router? Do off the shelf Thread Border routers (e.g. Google Nest Hub) typically allow thread devices to directly connect to remote IPs? 

Any alternative solutions?

Thanks for advice.

[Sigurd Hellesvik]

Hi,

Here are solutions I can think of:

• nRF52840: Bluetooth LE
  • You need some converter from BLE to Wi-Fi, such as a Raspberry Pi
  • You find a lot of cheap nRF52 boards
• nRF52840: Thread
  • Need OpenThread Boarder Router (OTBR). Either on hub as you say, or on Raspberry Pi.
  • If Thread is configured correctly, you should be able to reach the internet
• nRF7002DK: Wi-Fi.
  • Skip the middle man
  • More expensive. Less options for boards
  • nRF7002 is a extension chip, so you must use it with nRF52 or nRF53. (nRF7002DK has a nRF5340 on it I think)
• nRF9160: LTE
  
  • Use cellular network, directly to cloud
  • Can send SMS directly
  • Need SIM-card, so there is a running cost
  • More expensive than nRF52, but more boards than nRF7002. The nRF9160 Feather is very nice I have heard

That being said, the leak detection should work even when the user is not at home. So I believe this will require building a hub to bridge the BLE data to the cloud (e.g. a "BLE gateway")?

Yes.

Could the device instead publish the data directly to a server via Thread and a Thread Border router? Do off the shelf Thread Border routers (e.g. Google Nest Hub) typically allow thread devices to directly connect to remote IPs? 

In theory, you can reach internet from a Thread device, but usually not the other way around. So making a device that pings a server on a leak is a good use-case.
I do not know if off the shelf OTBRs have any limitations, so can't help you there.

Is this what you need?
Let me know if you got any questions

Regards,
Sigurd Hellesvik