Intelligent mailbox

Development 🇬🇧 Development Projects with Ruuvi products
1

Hey everyone!

I’m creating this topic to start discussion about an ancient problem:

One’s traditional mailbox can be located not close (in my case ~2 kilometers) and it’d be nice to check remotely if there is snail mail in the box or not.

With RuuviTag it’s possible to create a simple alarm system by utilising its movement counter feature if the box is close enough (within Bluetooth broadcast range). And in some cases this is good enough!

But.

In my case, the box is faraway and I’d like to have something more than just a notification when its cover has been opened.

But what to implement and how? Here are my requirement specs:

  • Has to work all year round (in Finland temperature drops sometimes down to -30°C or even less)
  • No external power required
  • Battery has to last minimum of 12 months, preferably 5+ years
  • Direct internet connectivity
  • Some sort of a camera (so that I can see what’s in the box)

Some ready-made solutions may exist, but I’m not yet aware of those. And, of course, half of the fun is to build it by yourself! :nerd_face:

This is the box:

photo_2020-09-11 12.27.07
photo_2020-09-11 12.27.071280Ă—721 310 KB

photo_2020-09-11 12.27.08
photo_2020-09-11 12.27.081280Ă—721 156 KB

Maybe something like:

  • nRF9160 (LTE-M / NB-IoT)
  • SPI still camera module (no need for video)
  • IR LEDs (for the camera to work without daylight)
  • ER341245 Li-SOCl2 battery (~35Ah, 3.6V, -55°C…85°C)

What do you think? Has anyone here created something like this?

1 Like
2

This is basically the idea:

mailbox
mailbox2000Ă—1437 696 KB

3

As a simple DIY approach I would suggest a raspberry pi, equipped with a SIM card and powered by a small solar panel.

4

Nah, that would be too easy and not reliable enough :cowboy_hat_face:

2 Likes
5

ESP32 camera and NB-IoT modem?

6

Not necessarily a bad idea. But a single SiP solution (nRF9160 for example) would be more neat. Need to think about it and make some more research on the options and also about memory constraints…

And yeah, for sure it would be possible to use a generic remote camera with an external antenna and forget home automation integrations and custom circuit boards, but would it be this much fun? :upside_down_face:

7

https://pycom.io/product/sipy/ board for comms. Or the LoRa version, although the range requirement sounds like it’s more than what LoRa can offer. https://openmv.io/ as camera.

8

Haha, I did this years ago… It was a lot simpler, though, as the mailbox was in my apartment building and I could even hear my wifi by the mailbox… I just wired a wifi chip (redbear duo, probably) to reset on the action of opening the mailbox lid and the whole firmware was connect to wifi, send an email “you got mail!” and go back to deep sleep, it lived on a couple of AA batteries for as long as I lived in that apartment…

9

The antenna must be a flat type, at the back of box, like in mobile phones. The antenna cable taken out from the bottom extra “water” hole to the back. Electricity meter antennas as a reference but flat.
The sensor? A stainless steel pin between the front and the back wall dropping down when something is pushed into the box ?
Battery, 1 loading in 12 months i.e. a rechargable lithium accumulator attached inside the roof plate or the highest point of the back plate.
Sleeping time for the sensor about 5…10 minutes. Burst sending.

1 Like