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


#1

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?


#2

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?


#3

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


#4

You’ll probably want something like this: https://shop.pimoroni.com/products/adafruit-rfm69hcw-transceiver-radio-breakout

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: https://forums.adafruit.com/viewtopic.php?f=24&t=85750

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.


#5

Thank you, now my project feels somewhat possible.

But the sms route, would you skip that?


#6

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.