$300 Food Computer - MVP

You are correct, Relay.py is where the GPIO pins are assigned. You can use any available GPIO pins on the Raspberry with the relay, just change the assignment in the file.
There was nothing special about pins 29-35. I just started using them, and once they were defined in the relay file, there has never been a cause to change things.

Thank you very much for quick answer. I’ll soon share some info about my build.

I love this add-on. I’m curious if your students can develop a way to put the full water bottle on without making a mess. This reminds me of a watering bowl my family used to have for our cat:

I’m curious, you said you’re using this in schools? Can you elaborate on that? I’m very interested to hear what you teach and how you’ve been able to tie the Food Computer into lessons.



How long does this last? Especially as plants get bigger, they can go through water fast. It might also be an issue to control the depth (how deep you set the bottle?).
Automatic fillers are useful, and this is a simple solution.


So I built a second food computer and I seem to be having issues with my temp/humidity sensor. It’s not updating on the dashboard and when I test it I get errors.
I checked the wiring and it seems correct.

Typically this is a wiring problem (switching data and clock wires), as this is a low level I2C level error. You may also need to check the solder joints. Could also be a problem of the wires connected to the wrong pins on the Raspberry.
You might try swapping the SI7021s between the two MVPs, to check if it is a problem with the sensor. If the good sensor works, you know it is not a wiring issue. If it doesn’t, then it is with the wiring.

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Guess the wires were bad. Switched sensors in the working computer and the new sensor worked. Replaced the wiring and the problem was fixed. Thanks.

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Glad it was an easy fix.

For us this mod works best when we are starting out and/or the plants haven’t developed long roots. We want to make sure the water doesn’t drop too low and the new plants lose their water supply and dry out. We’ve had that happen often.

Yes, once the plants get big they suck up one of these water bottles every day.

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Hi Peter. This project is for the Arizona Sustainability Alliance (AZSA) Food Systems Priority. The purpose of this project is to bring food computer and digital farming education to local high schools to inspire curiosity and promote food tech innovation. Utilizing food computer blueprints and open-sourced networking, this project intends on creating a food computer lab within a local high school, where students will be able to conduct experiments, replicate experimental data, and apply their knowledge to a small-scale digital farm located within the lab.

We obtained funds from Microsoft and are putting a total of 5 food computers in 2 different schools. Our current 2 computers where built and run with the science club in Glendale High School here in Phoenix Arizona. The project lead is Tearsa Saffell, she’s done an amazing job obtaining funds, organizing and managing the project. I’m the main engineer on the project dealing with the technical aspects. Tearsa, myself, and the two science teachers have used the food computers to teach the kids how to a) build things and use tools, b) learn about computers, code, and electronics, and c) learn about plant growth and all the varied aspects of that.


I keep having trouble with my light. The connection to the pin is bad. Are some wires better than others or is there a way to make a better connection. If I touch the wires the fan sometimes defaults to on even when the temp is low and the lights sometime go off at night and other times not. I have replaced the wires but they are from the same batch I purchased. Is there a type or brand that usually works well?

Hey, Pedro from Brazil!

I’ve just started to adapt the 300U$ Food Computer to Brazil in order to make it accessible to public schools and I hope to make a complete documentation about it in portuguese to foster a local community.

Wish me lucky :wink:


I have just used the generic stuff from Amazon.
The problem is often more with the connections rather than in the wire itself. Sometimes a little crimping helps.

Is there a tool for that? Not an experienced crimper

If you’re talking about dupont connectors (the little square things that you can use directly on micro controllers) then I like this crimper:

Don’t forget to get male and female connectors…that parts that crimp onto the wire. The little black housing squares or strips work for both the male and female connectors (typically labeled as female housing). It takes a little practice crimping. Don’t even bother with the really cheap crimpers…just a waste of time.

For the wires we use, I just pinch them with my fingers (bit difficult) or needle-nose pliers. Not out for accuracy, just squeeze them a little tighter.

Hello nerd farmers!
I am Shion who lives in Taiwan.
Since I felt bored and wanna have a pizza.
So I built a MVC to grow all the ingredients to make a vegan pizza.
(Since there is still no personal meat computer.)
However, I read a book called “かんたん水耕栽培” which means “simple hydroponic” in Japanese.
It said that is OK to use sponge as a replacement of rockwool.
But I tried and found my plants can not grow root on the sponge.
Should I change my growing method to DWC ?
And if I start to use DWC, is it necessary to use rockwool?

By the way, I also want to teach kids in Taiwan to grow and bake their own pizza. So I am looking for teachers in Taiwan for corporation. Please, contact me by twitter or gmail if you live in Taiwan and have the same goal.

Twitter: @shion_clockwork
gmail: hai10412014@gmail.com


Rockwool is convenient, but not necessary. In fact, in the last several months I have switched over from using rockwool to coco. I didn’t like that rockwool was not re-recyclable (and expensive). I simply fill the net pots with coco and everything else is the same (DWC).
Almost anything will work as long as it is chemically neutral and supports the plant and root growth. There are a lot of varieties of sponge, and an open-cell variety (which roots could penetrate) sould also work.