Fido, the temperature alarm that sends text messages

Tool Concept
Is your greenhouse getting frosty? How about too hot today? Is your fridge still on? Fido is a temperature alarm that will send you text messages that you can build for under $100. Solder together the Arduino based model or snap together the Raspberry Pi based model.



Fido is a farmer-built electronic tool that can monitor greenhouse temperature, record greenhouse data, and alert the farmer to problems in the greenhouse via cell phone text message and email. This tool is much more affordable than commercially available greenhouse alarms. Fido has been tested by several farmers to ensure that it is accessible and appropriate for various operations.

There are three Fido models. 

  • Fido WiFi:
    • Has a range of 100 feet from Internet source.
    • $118 in parts.
    • Does not require soldering, pieces snap together.
    • Configured by online form.
  • Fido Cellular:
    • Works anywhere there is cellphone reception.
    • $127 in parts.
    • Requires soldering skills.
    • Configured by text messaging your Fido Cellular.


To build a Fido Cellular, check out this guide. To build a Fido Short Range or Fido Long Range, see below. If you would like to purchase a ready made Fido Short Range WiFi or Fido Long Range WiFi, contact R.J. Steinert (

Build a Fido WiFi

Fido Short Range uses WiFi to send text messages and emails to you when it detects a temperature out of the bounds that you set. Because Fido WiFi uses WiFi, it will need to be close enough to a WiFi Router to pick up signal. It's also a 2.5 Watt device so if you plan to run it on a battery and only want to have to charge it once a week, you'll need a battery with a capacity of 24 hours x 7 days x 2.5 Watts = 437 Watt Hours. Something like the Goal ZERO Yeti 400 for $440 would do the trick.

Total cost of parts: $125

Configure a Fido WiFi





1 user has voted.
0 users have voted.



I had a look at your project because I have created a similar system, I just wanted to say that the power usage is excessive, even for Wifi. I have managed to create battery powered (4 AA Batteries x 1600 mAh) Arduino temperature sensors that communicate with a central node (Raspberry Pi) via NRF24L01 radio modules (that you can purchase for 2€ from China), this all amounts to a lower cost per sensor and a much better battery life (more than 6 months). I have documented some of my work here: 

The main node receives all of the temperature data which it can then store locally or send off to a server via Wifi (with a Wifi dongle), Ethernet, GPRS / 3G / 4G (with a GPRS / 3G / 4G dongle)... The server then handles sending alerts (emails, sms via Plivo), no need to hook up an old phone to anything, the SMS sending is done via the Plivo API (7 cents / sms)

I just find it crazy that buying a 400$ battery is even listed as a "solution" to the problem.