POWAR - Plant Observatory of Weather Adaptability for Resiliency

CNC cutter

Plywood Sheet (2000 x 1200 x 9 mm)

Rubber Mallet

Sandpaper

Brush

Wood Varnish

The POWAR main box, is designed with press fit joints, so that it doesn’t needs any nails to be attached, and it can easily be mounted, unmounted and transported.

It consists of four sides, top, bottom and a division for the electronics in the upper part. The left and right side are exactly the same, so as the front and back with the difference that the front has a hole for the acrylic door.

The box also has a división in the upper part to locate the electronics inside and to hang the lights and watering system below it.

The box has another division in the lower part made of acrylic, that is the one that will hold the plant and let the water pass back again into the tank.

After cutting it, you just need to properly sand it and cover it with a water resistant varnish so it lasts longer. It is very important that after you sand it, you clean the wood pretty well to remove dust, so that the varnish has a better ending. If you have an air gun, that will help a lot.

To help with the assembly you might use a rubber mallet.

 For building this, you are only going to need:

3D printer

PLA filament.

4 (8) x 5mm screws

SUPPORTS FOR ACRYLIC DIVISION:

After printing them, I would suggest that you screw them to the walls before arming the wood structure. That is going to be way more easier than screwing them with everything mounted. It is important that you measure everything carefully, so that they are all in the same height.

The only function of this pieces is to support the Acrylic plate that will hold the plant. But it is important that they have enough infill so the are solid enough to support the weight of plant, the soil, the acrylic plate and the water.

They are made so that they could be attached to both sides of the wall, which will give more sturdiness to the structure, but will also make it more complicated in the moment you want to unmount everything.

L JOINTS:

The L joints are going to help us connect the water tube with other tube pieces without having to bend it and therefore lose pressure. They are made to fit pretty well, but in case of any water dripping, you can add some teflon tape before joining it with the tube.

For cutting this parts you will need:

Laser Cutter.

Acrylic Sheet (600 x 400 x 5 mm)

The acrylic division, is a 280 x 280 x 5 mm piece of acrylic, whit a 10 mm diameter holes pattern, that will hold the plant above the water tank and let the water drain back to the water tank below.

In this first version I missed to add some holes that work as handles, like the ones I added to the door.

The door is 300 x 200 mm, it has some wholes patterns in it to give a little bit of ventilation to the plants, and because it also gives a cool look when the lights are on. It also has a whole that works as a handle.

At the beginning I was going to add also a metal hinge, but that mix of material doesn’t looks good, and actually, since the front wood wall has a pocket, it fits perfectly so it doesn’t needs it either.

You will need:

Adafruit Neo Pixel Led Strip x 30 LEDs (more or less if you want)

Soldering iron and materials.

3 colored wires (500 mm minimum each).

Silicon gun or double sided tape.

The first thing we are going to is to divide the 30 LED strip into 3 x 10 LED strips by cutting it with some scissors or a cutter.

Then, interconnect two of them with about 50mm of wire between them. Use the color coding to guide the Signal, the GND and the VOI. Use te rest of the wire in the first LED (read the light instructions fully before connecting).

Be careful to connect the Neo Pixels in the right direction, it is indicated by an arrow between each LED. This means the direction the current is moving, so keeping that in mind your first LED, the one that will be connected to the board, should start with an arrow pointing away from the wires, and that the ending led should also have an arrow pointing to the unconnected end of the strip.

Now with the silicone gun or the double side tape, stick the led lights to the surface separated evenly like in the picture. The longest part of the wire should go around the board, so that it connects to the main board in the other side.

Usually when you mount a Neo Pixel LED strip, you add a 470 Ohms resistor between the first LED and the board, but I integrated this resistor in the inputs/outputs/voltage shield so that there is no need to add it directly to the LEDs.

For building this you will need:

1 x Sumergible Water pump (5V or 12V)

1 x Plastic Container (280 x 280 x 150 mm MAX)

1 x 5mm water tube (1000 mm)

2 x colored wires (1000 mm)

2 x 3D Printed L joints

The container that will work as a water tank should go right below the acrylic division. You will have to be checking each week or two if you need to refill the container. In the next version of POWAR I´m going to add a water level sensor to indicate when you are running out of water.

In this first version, I´m using a 3.3 – 4.5V water pump, which actually works well with 5V. But anyway, I feel like it doesn’t has enough strength, and that´s why I´m going to use a 12V water pump in the next version.

The whole electronics for the POWAR have been designed in Kicad and it works under a ESP 32 chip, that give it the capacity to connect to it through WiFi or bluetooth. It also has a lot of PWM, Digital and Analogue pins that will help us connect different sensors and actuators for our purpose.

The main board of the POWAR device is the Barduino v2.0 created by FabLab Barcelona, which includes an FTDI and mini USB connection, so you don´t need an external FTDI to flash it. In the link you can find all the proper documentation from FabLab Barcelona.

Here is the BOM to build it:

 + BARDUINO V2.2 (FabLab Barcelona)

 – 1 x ESP32-WROOM

 – 1 x SOT- 223 (Regulator)

 – 1 x FTDI SSOP-16 USB to UART

 – 1 x PINHD-1×09-HEADER (male)

 – 1 x PINHD-1×13-HEADER (male)

 – 1 x PINHD-1×12-HEADER (male)

 – 2 x CAP 10pF

 – 1 x CAP 1uF

 – 1 x DIO SOD-81

 – 1 x Red Led

 – 1 x RES 10k Ohms

 – 2 x RES 49 Ohms

 – 1 x RES 220 Ohms

 – 2 x RES 490 Ohms

 – 1 x Slider Switch (AYZ0102AGRLC)

 – 1 x 6mm button switch

 – 1 x USB Micro Port

 – 1 x DIO SOD-123

*** The POWAR shield could be modified in the futuro to work with a NODE MCU – ESP 32 development board ***

One important thing in the building of the Barduino v2.2 is to solder from the most difficult component, in this case the FTDI and the MicroUSB connectors, and finish with the easiest ones… which could be de ESP32 or a resistor, capacitor, a led or the pins. Believe me, the FTDI and the MicroUSB could take you around an hour or more, if you are not experienced in soldering. So it is better to solder them and test them with a multimeter, before you continue with the rest.

One important thing when Milling the PCB board, is to keep in mind that the ESP32 Wroom need a clean space (without cooper) for the antena, so the order of the milling process should be:

Traces. (1/64)

Antena. (1/64)

Wholes (1/32)

Outline. (1/32)

Keeping this order will let you first mill the traces and then mill the antena with the 1/64 end mill (just to remove cooper), and then change the end mill to a 1/32 and do the hard work (remove PCB material) to cut it or make the wholes.

This shield is made so that it fits perfectly with the Barduino v2.2. It is going to be in charge of giving the power to the whole system, and also to connect the Barduino GPIO pins to the corresponding sensors and actuators.

Even dough the Barduino only uses 3.3V, it can be powered with a micro USB with 5V, and has it´s pins connected so it could also use those 5V from the VIN to power the other sensors, but I wanted to leave the energy supply away from this Barduino board and instead integrate it to the POWAR shield, so that it works with a 5v (miniUSB) or 12v (AC) to use depending of the power of the actuator you use, so you can use a bigger Water Pump and Ventilator if needed, and you can just change the voltage with jumper wires. 

The shield also comes with some specific connectors to add the moisture sensor, DHT temperature sensor, LDS sensor, the NeoPixel lights, the water pump, and the ventilator.

*** I´m still working in this part of the process, so I haven´t finished documenting the soldering and usability of it.

The POWAR platform, can run in a Raspberry PI or a computer. It is made using Node Red dashboard to connect the Barduino to a Weather Api which give him the information of the weather of the selected city.

In this dashboard you are also able to control te actuators manually, and connect more than one POWAR system to different weather specifications between them.

The Api im using is Open Weather App, mostly because the Node Red dashboard has a downloadable widget specifically for it, but I´m struggling at the moment with the configuration of the relations between the Api reading, crossed with the sensors and mixed with the actuators. So this is the part I´m working in wight now.

Even dough I explain the whole process of building the machine, POWAR could come with all of its parts pre-cut. All the walls of the structure the acrylic pieces, the 3D pieces, screws, NODE MCU ESP32 board and the pre-built sensors/actuators/power shield for the people only to build it and connected.

It should also come with its proper booklet, video tutorials and documentation for building it and experimenting with it, so that it is easy to use.

The booklet could explain the basic principles of how it works, and give the kids some examples or exercises to do at home.

I´m thinking that there could even be a simpler, lighter version of it that could be made out of cardboard, so that it reduces the shipping and production costs, so it can even arrive tho rural villages in development countries so that it help shortening the breach of technological education.

If a lot of schools around the world started to experiment with their future climates, we could even gather in the future a database of shared knowledge that benefits everyone.

What of people around the world could experiment growing plants in different climate situations, and we could gather that data and optimize the conditions for plants to grow in future weathers?