Checkout the video of the new Raspberry Pi based Fido. It's a plug and play temperature alarm that sends text messages!

The highlights:

• built using $78.50 worth of widely available parts
• no soldering required for assembly, it's "plug and play" thanks to USB
• designed to connect to WiFi but can also connect to cellular networks
• plans for automation and more plug and play sensors in the future

Checkout a video of me using the new Raspberry Pi based Fido

In the past few weeks Stefan Unterhauser and I have been working on a new design for Fido that is easy for farmers to build and deploy while maintaining a parts list that has a steady supply so that Fido can scale to the many farms that need it. We started with a new design that uses a credit card sized $35 Linux computer known as the Raspberry Pi, a $16 Temper1 USB temperature sensor, and a $15 USB WiFi dongle. This combination allows us to remove the need to solder together the many parts the Arduino based design required. We also removed the hard requirement of a Motorola C168i which is out of production and only available in limited quantity as a used phone and replaced it with an Internet connection dependency that sends text messages as email (free text messages!). We built a shiney web app that is hosted from the Raspberry Pi that users use to set up the WiFi connection, min and max temperature limits for alerts, define their alert phone number, and many other things. Also in the works is the "lite" version of Fido that we are building around Android and the Thermodo Temperature sensor that snaps into the audio jack. The design has the least potential for expanding but will be the easiest way to get started with a temperature alarm that sends text messages.

At the iFARM event at Tuckaway Farms in NH this year, we brought 14 Raspberry Pi Fidos that we had built. We managed to find new homes for 7 of them, 4 of which are now deployed at in one of greenhouses at Wild Miller Gardens. In the coming weeks we'll be writing documentation on how to build your own Raspberry Pi Fido and we're also thinking about doing a Kickstarter to sell preassembled Raspbery Pi Fidos.

To understand why we've been working so hard on other Fido models, it's important to compare the different designs. Below you will find a design synopsis of the three Fido designs in existence. I rate each model on five different qualities that get a score of 1 to 5. The higher the number, the better I think that design does on that quality. Each design gets an total score. A total score does not necessarily indicate a better design for any particular farmer as each person will have to decide for themselves which qualities are most important to them. If you think my analysis is off or I'm missing some information, do let me know! We could use your advice.

• availability: The likelihood a farmer can acquire the parts list now, in the future, and at scale in case it becomes a popular design.
• buildability: The likelihood a farmer can assemble the parts list into a working unit.
• deployability: The likelihood a farmer can deploy the unit into an real life situation.
• usability: The likelihood a farmer will be able to manage the device in a deployment.
• expandability: The likelihood a farmer will be able to expand the device to do other tasks other than the original fido design goal.

Arduino based Fido

The Arduino based Fido is the original Fido model designed by Louis Thiery as lead developer and some help from R.J. Steinert and Ben Shutes. It is based around an Arduino that is listening to attached temperature sensors and then sending the owner a text message through an attached cell phone when an owner defined max or min is reached. The owner defines max and min temperatures by sending a text message to the phone the Arduino is attached to.

Parts list

Item Cost Arduino UNO $30 Datalogging Shield $20 10K Precision Epoxy Thermistor $4 SD Card 1GB or more $5 Enclosure $15 9V Power Supply $6 Phone RelatedMotorola C168i + SIM Card $30 3/32 Minijack $4 Logic Shifter $1 Back-up BatteryBackup 9V Adapter $6 2 Diodes $1.50 2 DC barrel jacks $2 Protoboard $2 ------------------------------------------------------------------------ ----- Total: $127

Design analysis

quality score description availability 2 This design scores low on availability due to the amount of parts required an a dependence on a cell phone that is no longer being produced. buildability 2 This design scores low on buildability because many parts require soldering. deployability 4 This design scores decently because of the use of cell phone towers is familiar with most people as well as the text message interface is something I believe most people can follow. usability 4 As long as some notes are taken, interacting with the design's text message interface over time should be fairly straight forward. expandability 5 Because of the use of an Arduino in this design, potential for expansion is high given doing many automation tasks with Arduino is a well understood problem. ------------- ----- ----------- Total: 17

Raspberry Pi based Fido

The Raspberry Pi behaves as a Ground Server that listen to a USB temperature sensor. The Raspberry Pi broadcasts a website on the local network it is on which the user can use to define the minimum and maximum temperatures to be alerted on. When the minimum or maximum is reached, the Raspberry Pi emails a text message to the user's defined phone number. The goal of the project was to reduce the level knowledge needed to assemble a Fido. The design achieves this by using WiFi and Temperature USB peripherals that do not need to be soldered to the Raspberry Pi board. Because the design uses the Internet to send text message alerts, the design is built to easily configure a connection to WiFi networks. The Raspberry Pi based Fido was designed by R.J. Steinert and Stefan Unterhauser.

Parts list

Item Cost Raspberry Pi $35 Class 10 8GB SD Card $7 Micro USB male to USB male cord $1 USB Power Supply $4 USB Temper1 Sensor $16.50 TP-LINK 150Mbps Wireless N USB Adapter $15 ------------------------------------------------------------------------ ----- Total: $78.50

Design analysis

quality score description availability 4 All parts on the list are in production and show no signs of dissappearing any time soon. The weakest link is the Temper1 USB temperature sensor which is a niche product for the server market. If that one company dissappeared this design would have to change substantially. buildability 4 All of the parts are "plug-and-play", in other words there is no soldering required. A challenging part of building is the downloading and copying of the software image to the SD Card. While there is a great utility for this for Windows, it's still requires some technical confidence. deployability 2 This is the largest challenge for the device. It requires understanding understanding some basic Ground Computing principles like the fact that the Fido is serving a web page that is not on the Internet and can only be accessed when connected to the local network. While a simple concept, it is a tough thing for many people to grasp at this point in time. Another challenge for deploying is that if you are not profficient in deploying large WiFi networks, you'll probably opt for going with an Android device broadcasting WiFi. While there are many options to connect this device and that is good for power users, I think less technical users will be overwhelmed with the options and struggle with he option they do pick. usability 3 While not much interacting with the device after deployment is required, if the user wants to tweak settings they'll have to remember how to use a seperate device to access the Fido on their Local Area Network. expandability 5 Because this design is built around Raspberry Pi, using it for further sensing and automation applications has well known solutions, see GrovePi. ------------- ----- ----------- Total: 18

Android based Fido

The Android based Fido consists of an unlocked $50 Android phone and a temperature sensor that fastens to the audio jack. Minimum and Maximum temperatures are entered in a Fido Android app. When those limits are reached, the phone's internal text message capability is used to send the message. The design goal for this design was to reduce the complexity of setting up the device by using the Android App experience as opposed to the Ground Computing paradigm of using a Raspberry Pi.

Parts list

Item Cost Android phone $50 Thermodo - Audio jack temperature sensor $30 ------------------------------------------------------------------------ ----- Total: $80

Design analysis

quality score description availability 4 I've been watching the price of Android devices fall for many years now. We're now at the point where there are many options for tablets under $100 and many more Android cellphones for under $50. There's an entire economy built around these devices which gives me reason to believe they aren't dissappearing any time soon. However, the temperature sensor is from a single company where the underlying technology is not a well understood solution. The HiJack project had some great steam but doesn't seem to have had much activity in the past two years. Also, the HiJack project's approach may be overly complicated for this need. We just need to get temperature from the external device, while the HiJack project is designed to receive and send data to an external device. buildability 5 It's hard to imagine a solution much easier to build. Snap the temperature sensor into the headphone jack on the phone, plug the phone in. deployability 4 Placing a cellphone in a place with reception is a familiar problem to many people. This design also has the added benefit of being able to use WiFi if the cellular network is not available. usability 5 The paradigm of downloading an app and opening it is well known to many people. expandability 3 Android devices could be expanded via their USB port or microphone jack but there are not well known solutions using these methods to accomplish sensing and actuation. The ability to join WiFi and send HTTP calls to other devices is possibility, but again, it's not a problem space that has been explored much or that is very common in agriculture especially. ------------- ----- ----------- Total: 21