making sensors case

I’ve had hours and hours on thinking what kind of enclosure would we use in the the sensors and board. you know.. 3D printed.. plastic tubes.. acrilic.. and the answer was always in front of me.. the canes we use to hold the tomatoes :) you just need to find the right diameter so the sensor could fit.



also for the boards I use this glass jars. they are perfect, completely clear so the luminosity sensor can work without interferences, the metal lid can be easily cut to pass the cables and with the elastic rope they don’t move but are easily open and removed.


the new boards have finally arrived

buff 3 months waiting for this boards.. I though that would never come and we would lost our money..


the left is for the farm or composter, the one in the middle is to connect to the weather station and the round is a sensor of temperature and humidity that we will use on various locations.


Like every prototype there are stuff that don’t come right on the first versions.. the leds are rotated and don’t work.. had to desolder and rotate but they are so small that this fixes are almost impossible to go right.. so we are correcting all the bugs and then apply them to the quirhort farm. see you soon ;)


day#9 workshop @ iaac

today we started our two days tour over barcelona city trash. first stop: Solidança 2014-05-22 at 13-42-24 on our workshops we always have this idea of building with what’s available and every city has their own trash dinamics and trash resources. and barcelona would not be different. Talking with Isabel Gimeno from Solidança we both aggre that after joining EU there was a big efford on regulate the trash and since then we have a strong environmental protection policy and a cultural conscience started to grip. I’m a caver since 14 and I’ve saw many weels and deep caves filled with all sort of trash: cars, medicines, sick cattle, cloth, batteries, electronics, house and industrial sewage, just to name the ones you can quikly identify.. me and caves al over the world have spend incontless hours cleaning this mess many times preventing or at least reduce the inevitable water contamination that occours with this human behaviors. lucky in recent years we don’t see has many trash on the caves and generaly dumped next to a river flow. we have became cleaner in europe but we still have many unresolved problems: stuff that is impossible to reuse or recycle, lack of design for disassembling or designed to be imposible to repair, over consumering etc 2014-05-22 at 13-34-10 Solidança, apart of managing 4 big collection centers, brings new value and meaning to coth, electronics and house appliances. Solidança also has a strong social commitment. giving workshops of waste managment, electronics and electrical appliances reparation, gender equalty, new tecnologies, social competences, etc. 2014-05-22 at 16-29-21 Solidança also reseaches new protocols and systems with this idea in mind: work to reduce poverty and protect the environment. 2014-05-22 at 14-40-27 we were warmly recived by Miquel Caballé and Isabel Gimeno who gave us a quick tour and a long chat :) 2014-05-22 at 14-01-38 2014-05-22 at 15-02-00 2014-05-22 at 15-06-28 we then went strait to what was waiting for us: 60 washing machines. 2014-05-22 at 14-44-45 2014-05-22 at 14-52-38 2014-05-22 at 14-58-52 2014-05-22 at 14-58-57 2014-05-22 at 15-47-04 2014-05-22 at 16-07-12 and this is the final result: 6 pressure switches, 2 water pumps, 6 electro-valves, 1 flowmeter!! and several other things to you know.. hack :) we ended the day with Merce Jara (tks for all ;) with a suprising tour to l’Hort Fort Pienc. 2014-05-22 at 18-46-10 2014-05-22 at 18-46-56 2014-05-22 at 18-47-00


Screen Shot 2013-08-12 at 11.53.38 AM

uau!! 2 lines that made us jump of joy :) so next september you will find us in brasil developing a electronic faucet/valve that can be made in a 3D printer. here you can see our proposal.

I’ll keep you posted on the developments here on the blog and on the wiki. please if you want to contribute feel free. the e-valve is a complex project so every help is welcome ;)

mini vacations board

yesterday martin hug just send us this


it’s our new mini vacations board V3. the mini is meant to control the UFRRJ watering system, collect/store data and has an optional wireless data socket to upload data or change configurations.

contents: ATMEGA328, EEPROM serial 256K, usb port, FTDI, wifly, 3V rele, Li-Ion battery.

we’ll are making 10 of them and we need 10 developers that are willing to take one and start debugging :) we will realease them free you just have to tell us why you want it and figure out a transportation solution from barcelona to you :p




mini vacations board


I’ve team up with andreudani aguilar, miguel heras and svetlana. we are developing the new mini vacations board on hangar.org interaction labs. the idea is to review our main board to a SMD version that would be cheaper and include new functionalities. an on board battery that would allow memory backup, a new energy management, wifi connection, ambient light, temperature and humidity, support for various sensors, new satellite boards that will expand funcionalities: solar panel, extra humidity sensors, 12v and 220v relays, air gases detection and a web camera.

after the first prototype is ready andreu will start to manage the data that uploads to the servers and dani will work on the mobile app that visualize and monitors the data of each board. it’s a huge project and we will be posting here the developments. tks everyone for team up with me, it will be a pleasure to work with you guys ;)

and for you, you know, you can always come on board if you are a developer or just simple interested about our work ;)

stay tuned, the next 2 months here in barcelona will be intense heheh

refarm kids


electronics: david pello

Hoy en día los vegetales viajan muchísimos kilometros por aire, mar y tierra. Pasan por procesos de congelación y desolación. Estos alimentos pierden propie dades y sobre todo sufren desgasto nutricional para nuestro cuerpo. En realidad, hay una gran variedad de vegetales de temporada que se pueden cultivar dentro de nuestras casas. Vegetales que simplemente habrán brotado, crecido y se habrán recogido para hacer una comida. Pero a veces no sabemos cómo cultivar y organizar nuestra huerta. Hoy en día tenemos tecnología que nos puede ayudar a mantener nuestras huertas y además nos permite comer saludablemente. ¿Te gustaría participar en esta experiencia?

refarm edu propone un ciclo de percursos lúdicos para niñ*s de exploración de herramientas destinadas a la creación y monitoreo de huertas urbanas. Durante las actividades los participantes podrán experimentar el uso de herramientas tecnologicas aplicadas a la producción autónoma de alimentos. La idea es intro ducirlos en la gestión de una huerta y experimentar el uso y la creación de aparatos tecnologicos que sirven de soporte al mantenimiento de nuestros cultivos domésticos. En el espíritu del DIT, do it together, se propone hacer un viaje por una huerta urbana donde los niños empezaran a mover sus primeros pasos en la creación cooperativa de tecnologías útiles para el planeta y nuestro bienestar.

revised nano vacations board

remember this blasting board? ok, finally got the board revised by david prelo :)

soon we will post some more pictures on how to make this board with cardboard and fabric!

yeah, I’ve been working with circuits on fabric mainly because since beijing I don’t have a solder iron. I also don’t want to spend money and energy so fabric seems the most sustainable solution :)

nano vacationsV04


They first thing is wanted to change this time is the power supply. The ATX power supply  hack is way too much for one sensor, too loud and too expensive. Too buy a 12 v leiser  batterie that is connected to a solar pannel that recharges the batterie, is too expensive ( ding ding ding ) . So i decided to use old electrodomestic transformers.

Transformers are quite commen. Those are those black boxes that come with everything you buy that needs electricity.The work of the transformer is that is converts the 220 AC into DC and the voltages and ampers whatever is need by the consumer product.  You found them in every flewmarket in all shapes, forms and voltages and amperes.  It could be a nasty task :)

I picked up three different types all of them 12 Volt and amperes from 400 mA to 60mA and payed 2 euros each.  I took a sony which a chinch ending , a langelsbold with a handy plug ??  and a matra with a network plug.

The first one i tested was the sony.  I cut of the plug and there where just 2 wires. The measuring was 18 V. 6 Voltes more then expected( cheap multimeter proberly too ) . I workd well with the 12V waterpump from the windshield cleaner and it worked well with the electrovalve 12 V. In use or standby it gets slightly warm , which means it is not of the newest generation and that it consumes a little standby energie.

The Langenselbold didnt worked? I really dont know why. I  did a short search on google where it comes from and i found nothing. I appearas that langensbold is a town in germany.

The Mantra adapter with the network plug was i big suprise. You can power 2 pumps with on transformer. The foure wires are coloured  black, yellow, green and red and the work in pairs. The output voltage was similar between the 2 possible solutions. Grenn + yellow with 14,5 Volt and black and red with 13,6 Volt. On the  transformer is written that it powers the 11 V with 60 mA. That is significly lower then the Sony , but it worked well with the LED, pumps and electrovalve. So conlusion , just look for the voltages and it should be fine. Reuse old transformers is cheap and good and re:farm . You can power your devices easily with the wanted voltages. The current is stable and safe. With the ATX power hack i alwayes had short circuits and it was annoying to work with.  When you just work in one range of voltage a AC/DC transformer can be the choise to go for to power your selfbuild things in a clean , cheap and save way up.



small, pretty and blasting :)

são paulo report and some considerations.

we try this one here in são paulo. the nano vacations.

don’t let you misleading by the nano scale. ok, it’s small (the diagram is 1/1) inexpensive 2$+ecofootprint, and can be mostly scavenge in a city.

still on the scale perspective and scales we don’t see, most of our electronics work on micro, nano or pico scale but the above inexpensive ecofootprint can be bigger than the 2$.. can be a 2K$.. we just don’t know.. I didn’t make the maths on the energy embodied  nor the ecological impact of our tools.. how many tons of minerals are dig from mountains and were are this mountains?

we extend the live of some materials but we also use a small % of new materials.

we also got “bugs” on the electronics hehehe in january I got this

20 tip 120 on a electronics market in beijing by 10$. when you connect 12v to them they just blow.. so insted of a tip120 darlington transistor I got 20 units of a 12V non reusable bomb that gives a blasting sound. if  this is exactly what you were looking for, I can sell them to you:p

so we just setup the watering system without the nano blasting board.

located here and by the bytes changed with pixel, the last day of the workshop was on the garoa hacher space.

wau, what a place.. full with electronics, friendly people and geeky too :) being geek is one of the most intensify intellectual activities in our days apart of fun, open and creative. thank’s guys ;) you will be a great partner of the SP re:farm group.

back to the small, pretty board: the idea is just to have some control over a system that has a bottle that recovers rain and a windshell water pump that handles the watering. the moister sensor (has a tribute to this guys) was made with local materials.

we got this boxes on a country fair around the corner.

daniela brought her used filter,

we got the water pump 2 doors away by 10RS

we got the soil from an hippic place

the bottle was gently offered by a local store (it’s amazing how people give you things when you ask materials to make a urban farm :)

in 3 days we got local materials, build one re:farm, one vermi-composter, eat good food, good drinks and of course made new friends :) looking forward to come back heheh


new ultra low budget re:farm board (aka mini-vacations)

we have been working on this our A3 re:farm. everything fits on a A3 envelop ;)



we need to change our strategy over the electronics. the arduino platform is to expensive and truth to be said is like that guy that as a big car to drive on the island. we really don’t this that much electronics or processing capability of the ATMEGA.. so let’s shrink the design of the board and reduce the bill :)

A3 refarm electronics

pressure switch communication

So it definetly works!!!  My depest repect to you Mr. Medici. Your self automated watering sytem is the best low budget automated watering sytem and it beats all comercial products. 10 John Meda simplicity points for your design. I definitely fall in love with it :).

What i have seen is that it took nearly 49 houres for the plant to consume sufficent water and to overcome the hight distance between pressureswitch and ceramic sensor to do the switch.

To do the reverse operation it took nearly 50 min or to be less precise 1 hour. I handwatered the plant with about 400ml of water , directly , no dripping system. Thats the next point about this system. If it is indoor it must be precise , otherwise you water your carpet too. This will be relationated with the tubes-diameter, folds and switches inside the system, the kind of valve and pressureswitch, the waterpressure, the hight of the watertank etc.. But it is not a real problem you can addjust all this parameters with the height of the pressureswitch.

mange bien :)

Till i find out how the wiring is done for the pressure switches i decided to make a little test about the response time of the system. What i want to find out now is,  do that really works at my place with my parts and how much time my plant needs to drink the water from the switch and does it  switches. If this is done I will water the plant by hand and i will see if the process will be reversed and the switch will go back in his OFF state.

The plant is a present from a friend of us and I have no idea what typ it is, but I very happy with it and sometimes when I’m out I give here a place next to the window to enjoy the day. I watered that plant  in summer at here house and it is a very thirsty type. In a previous posting about the ceramic sensor i found out that the plant consumes about 15 ml in 24h. ( proberly, I  didn’t measured they water amount , because i dont have that equipment ).

I filled the switch and the sensor with water , and it is imposible ( with my tubes etc… ) that you dont have air in the system, but i  think that that will not be a problem. So i filled everything. The switch made click. It just takes a little amount of water, my tubes are very small, so i think the system is quite responsive.

I checked they continuity at my ports and they measuring gave me the values:

Filled = switch OFF = pin 21 + 23  =  000 /   pin 21 + 22 = 1

so during the next 24 h they continuity should change if they plant drinks the water from the switch.( yummy )

What I forther  did was to water the plant a little around the sensor. As you can see in the foto the water passed the earth and a little stayed in the groundplate. What I have seen then is that the earth absorbed that water during one hour into the system and that made the bubbles in the tube move down( 2 cm) . So it looks like that he system is really good responsive :). One point more , the switch is 40 cm under the flower pot, that is importend , because the system and the pressure relates to the difference in height from the sensor to the switch.

pressure switches / pressostate

The 2 differnt types i bought and i have no idea how they really work, but with the help of the internet I found out that one of them is  from a dishwasher and not from a washing machine. With a multimeter I made a continuity tests and it looks like that one is having 1 trip points and the other is having 2 trip points.

With the contiuty test you can test the pins how they respond and if the work.  You just have to measure two  pins and them blow into the switch, if the switch works you hear a click from the switch and the continuity will change from 1 to a 3 digit number and vice verce. Those pins will later be connected to the solenoid valve or water pump and send the signal to water our plants :)

Here is small video that explains pressure switches.
youtube pressure switch video

marché aux puces (fleamarket)

In search of the pressure-switches i decided one grey sunday to go the marché aux puces at  Porte de Clignancourt, which is  the bigest fleamarket and the oldest fleamarket  worldwide. It is a marvellous place where 3 times a week you can find from  very antic furniture and aireplanparts  till the latest underground french hip hop bootleg from the banlieu and other curriosities. And you can get there pressure switches. I bought 2 different types and a small motor for test reasons for a very nice price.  It was very nice day out in Paris :)

day#5 at TASML

I’m a bit tired now.. been debugging all night and this is still not working..

but, let’s go by parts:

physically the farms are ready to receive our plants. we have chosen 2 chinese dishes from the gigantic asian gastronomy.

the scarecrow looks amazing and all the sensors are in their position.

the bad news comes from the electronics. I’ve found some errors. they are my errors and the pcb factory didn’t saw them also. see the pink lines?

I didn’t saw them… they represent unrouted connections. not a big deal but I had to make some jumpers

dirty job I know. but if only this works I’ll be happy. but it’s still not working and I don’t have a F.. idea what’s wrong.. need more equipment and a electronic engineer ASAP. tian li says that he has a friend that could help us. let’s give this and myself a couple days of rest.

so.. it seems that today is not the last day of this workshop :) more news soon.

day#4 at TASML

building electronics.

everyone made soldering today. we have prepared 2 boards and now comes the hard part: debugging :)

we have also made the watering system for the 2 farms. we didn’t bought tube since we found a big ethernet cable. we are gonna use the wires to connect sensors and the water pumps to the board. we used the external tube to make the watering system. recycling and low budget are our guidelines ;)

we have finished earlier today and we were able to wire one board and made one quick test. but it’s not working.. it never works at the first shot :p I’ll take this home to see if I can see what the problem(s) is. tomorrow is the last day of the workshop.

day#2 at TASML

in the morning we went to buy some electronics. amazing place this zhongfa market :p

then we spend the day knowing each other, sharing knowledge, speaking about everything green related, building the farms and getting some more materials

we even started a mini composter, a fundamental piece on the urban farm scenario. what would be of us if the worms didn’t give us a hand (or a bite:) on closing the cycle ??

About temperature sensors

I’ve been experimenting with and reading up on the LM35 temperature sensor, used by the On Vacations board. The output pin of the sensor connects directly to an analog input on the Arduino, and after reading the value of the pin, the temperature (in Celcius) is calculated with this formula:

temperature = 5 * (analog value from sensor) * 100 / 1024

However, I found that the temperature values fluctuated by 1 or 2 degrees for every reading (taken once a second).  To stabilize the readings, I tried to average the readings in various ways, such as by taking several successive readings and then averaging the values, or by keeping an average of the last 10 readings (over the last 10 seconds).  The results were quite similar in each case, the temperature reading was notably more stable, but when it did fluctuate, it was still by a degree or two.

In reading about taking better readings from these sensors, I came across lots of info about some general downfalls with Arduino’s analog readings.  There are two particularly relevant posts on the Adafruit forum here and here, regarding multiple analog readings from different pins.  The solution seems to be the inclusion of a short delay (10ms) after each reading.

Adafruit also has a nice tutorial on temperature measurement, and it sounds like the LM36 might be a better choice for use with the On Vactions boards — depending where a farm/garden is located — since it can measure sub-zero temperatures without a negative power supply.

I also came across a library directed to improving Arduino’s analog functions.  I’m looking forward to experimenting with this.


The LEDs are on the wall

Greetings!  I’m happy to make my introduction here on the Re:Farm blog.  My name is Andrew O’Malley and I’m a Canadian artist/engineer.  My main artistic interests are animated lighting installations and fixtures, and electronic music production and DJ’ing.

[ Eyebeam bio ]

These interests have brought me to NYC for the summer of 2010, where I’ve connected with Hernani’s Re:Farm project through his residency at Eyebeam.

My first objective is to create the PCB (circuit board) for the Re:Farm On The Wall module, a data visualization module using an LED display to present data away from the computer screen.

Here’s Hernani’s original sketch for displaying the soil moisture level from 6 sensors:

This design uses 7 LEDs to display the soil moisture level for each of 6 sensors (42 in all).  The design concept has been formalized as seen below:

The module still has 7 LEDs for each sensor (or farm/garden), but with the addition of LEDs between the groups (for a total of 48) to create a complete circle which can be used with other templates, such as the one below, for visualizing other data such as temperature or humidity:

Ideally, the board will also incorporate a stepper motor to drive a needle (like a speedometer) for an additional data channel.

I’m going to first concentrate on the LED display.  Since the board will make use of an ATMEGA microcontroller (Arduino) chip and an XBee radio (to receive the data), real estate on the approx. 3″ x 3″ board is already a bit tight, so I am currently researching Charlieplexing, an LED driving scheme which allows N*(N-1) LEDs to be directly driven by N pins of the microcontroller.  8 data pins from the microcontroller  can thus be used to control the 48 LEDs since Charlieplexing with 8 pins allows control of up to 8*7=56 LEDs.

At The Next HOPE conference this past weekend, Jimmie P. Rogers was demo’ing and selling his LoL (Lots of LEDs) Shields for the Arduino.  He has a great post about his work with Charlieplexing which I’m currently consulting.  Talk about serendipity!

In a way, the overlap between the needs of Hernani’s project and my own interests in lighting and internet-enabled lighting fixtures is serendipitous as well.

More soon!

garden and electronics

As you know re:farm has its own electronic hardware.  A  selfdesigned electronic card that is a all in one solution for the electronic enthusiastic farmer. A full functional adruino on board, humidity sensor,  light sensor etc etc. // detailed information on the wiki ->re:farm on vacation board
I haven’t paid for it till now, so i dont know the price for it. Just to mention that. It comes naked with all the parts that you can than later sold onto it by yourself. Quite a funny task. I had hardly ever solded electronics chips, something that is quite small and fine to work with.  Generall i  had a littlepit of respect for that small electronic parts, at least for the digital parts. They break easily, or at least you think, but this is something that changes when you get used too working with them. It changes from esoteric to something quite physical, which i think is a good step ahead. The solding is quite simple. I followed the manual made by hernani. Now with the wiki it is way more easy i think. I just solded one part wrong. The electronic parts look quite the same and the diagram hernani made was usefull but strange but true – one photo says more than a diagram:).

Solding the card is quite an easy task and you can make it all in one day easily whitout any previous knowledge. The testing is a bit more complicated. I have a basic knowlede of adruino and electricity, but something simple how do i plug this thing in needs his own tutorial, but with the help of hernani we made the first testing with my waterpump and my re:farm on vacations board is ready to let it rain.
The foto shows hernani, with my card hooked up to the powersupply of an old computer and the waterpump from my car that found his final rest in a car cementary here in Barcelona.  Rest in peace Astrobotnia , at least some of your parts get reincarneted in an urban garden. That is quite a good afterlive.

disulfuro dipropilo en el taller

Y llegó el momento de construir mi placa para disfulfuro dipropilo. El huerto de cebollas.

El momento esperado, el momento de introducirme a la electrónica. Un gran mundo de millones de herramientas con nombres aún desconocidos para mi. Soldador, alambre de estaño y miles de pequeñas piececitas que todas juntas dirías que son como pequeños insectos hermosos.

Hace ya días Hernani me entregó un sobrecito de color marrón que contiene todo lo que necesito para soldar mi placa. Dentro, todas las piezas que he de ir soldando una a una para hacer funcionar la placa que alimentará y cuidará a mi huerto cuando yo no esté.

El proceso está siendo muy lindo.

Ahora puedo soldar, ser una chica de taller, tener una placa de re:farm y saber de lo que se habla en estos talleres de electrónica.

¡Ahora sé que estoy preparada para lo que sea! :)

Y acabada la placa llegó el momento de probarla, ver si funciona, comprobar que cada pieza soldada está correcta, comprobar que la bomba de agua se puede controlar. ¡Y todo funciona!

Os dejo con algunas fotos del proceso “taller”.

share the design and share the knowledge

we are not here to sell electronics nor boards. that’s why we share the designs and have a wiki, you can make your own refarm. there are no big factories producing our boards only small ones and they are the refarm groups that we are step by step spreading all over the planet. for example we are now in buenos aires and we don’t have any board with us. we contacted a local factory DAI ICHI (the only factory we fond with environmental concerns) we send them the designs and they are gonna make 20 boards for our workshops and the cceba farms. since we love process you can have a look on buenos aires flickr set and take a tour on DAI ICHI.
we were very welcomed by mr. henrique shoji. it will take 1 week to produce them so in the mean time we are going to find the components. I think farnel has some kind of representation here in argentina.

despise all this intents to get everything local from the seeds to the soil there aren’t components manufactures spread all over the planet. all the electronics in our days are produced in china and her neighbors. amazing china :) china has also more than 1000 different varieties of rice!! we definitely must go there:)

this is why we are here. we want to share the vegetables, know their conditions, their properties, how they fit on your gastronomy and on your urban farm.

after working all day in our wiki.. now we are gonna share some beers with articultores group :)

boards arrived

bufff living on the edge. the clock is always tick tack and the boards came on my last day in portugal:) but I still had time to assemble 2 boards with tiago in lisbon hehehe

the job is perfect and clean although they forgot to print the silkscreen layers.. this boards came from the other side of the planet swimming trough sharks and skipping santa-claus-snail-mail-traffic. we asked seeedstudio.com to make them. it cost us 89$ plus 33$ shipping to portugal. 122$/ by 10 boards “on vacation” and 10 “on the sofa” gives a 6.1$ each board. nice price since it was a very ultra-low-small production.

here it goes the local-sustainable-environmentally-friendly-talk of the refarm speach :( and wait until you see the list of countries where the components are made.. there falls the local talk also..

but on the “safety” side of the materials used on this boards there is only one component that we still didn’t find a Rohs compliance version and that is the LDR (Photo Light Dependent Resistor) everything else is “green”

well green is what they call it but is more a greenish-brownzing.. the RoHS directive, stablished by the european union, calls for the near elimination of 6 chemical substances used in most electronics and electronic equipment: Lead(Pb), Mercury (Hg), Cadmium (Cd), Hexavalent chromium (Cr6+), Polybrominated biphenyls (PBB) and Polybrominated diphenyl ether (PBDE). despise all the components that we are using in this project are at least “RoHS compliant” we still have a scarecrow that would damage the environment and ourselves if not correctly disposal upon is end of life. and you know how are the objects, they don’t last forever but some of their raw material do. take mercury for example: it crosses all the food chain and rests on the top. by the way is you , your neurons, your cells, your friends, your mother and her grandson.. there is something in the word ecosystem..

list of countries in which last significant manufacturing process was carried out:
>TW Taiwan
>CN China
>PH Filipinas
>IN India
>TH Tailandia