Best way to do a temperature sensing projekt without access to wifi or power

Hi! I’ve a project where I want to sense the temperature/humidity where I got no access to either wifi/ethernet connections or power and want send a notification without using too much power being on a battery.

So far I got thinking around using a Adafruit Feather or likewise with a gsm module but that looks quite expensive (which is not a deal breaker but…). Another thing that came up was to utilize radio but I don’t even know if that is possible since I got no experience there.

Previous projects has been various sensing stuff with raspberry pi’s but those boards feels a bit overpower for a “lite” project as this.

Any ideas?

Depending on where you want to deploy it and what country you’re in, you may be able to use anything from a pair of simple long range serial radio breakouts to LoRaWan or SigFox and probably a whole bunch of stuff in between.

What are the distances involved?

Based in Sweden. Well perhaps around 25-35 meters to where I can put up a hub so to speak.

You’ll probably want something like this:

Albeit these are still overkill- in the right conditions they can achieve multiple kilometres of range.

You’d probably want a Feather with one of these modules, and a corresponding module to connect with the host.

As for whether that should be a Cortex M0 or ATMega 32u4 feather- it’s debatable, some good info here:

It will boil down to what you’re most comfortable working with, since either one of them can be set up to have extremely low idle power consumption.

Thank you, now my project feels somewhat possible.

But the sms route, would you skip that?

The power requirements for GSM would be higher, it depends if you want a solution you can deploy even further outside of the range of other networks or if you want the slightly easier/possibly more robust in some cases GSM.

GSM has to find a network, register, etc before it can even transmit any data. LoRa and similar radio setups just fire-and-forget.