This is the second Instructables FBRKN is making after the strawbees build night we had a couple of weeks ago.

We were trying to find ways of using the strawbees to something besides playing and building goofy geometrical structures so we came up with the idea of making a plant trellis for the office. And since we have a little of everything lying around we thought why not combine several projects into one?

So we added some addressable RGB LEDs and an Arduino Uno to control them.

PLEASE note that this Instructable DOES NOT explain Arduino, programming or any in depth things about how the program works. There are other awesome Instructables that explains that.

Step 1: Get Your Materials

This Instructable uses quite a few different parts and a lot of strawbees, to make it you need the following:

MATERIALS

Strawbees and straws - We won't tell you which parts to use or how many, it is all up to you and how big a trellis you want to make.

one Arduino Uno or other compatible micro controller (and USB cable)

Addressable RGB LEDs (we used these

http://www.adafruit.com/products/1461 )

4 mm clear acrylic plastic (you can use thinner but you will need to alter the illustrator file accordingly)

0,2 mm Enamelled copper wire (you can use any thin electrical wire, we choose this one because it's thin and easy to hide)

Solder

TOOLS

Soldering iron

Hot glue gun + glue

Pliers to cut the metal wire

Scissors

Ruler

Step 2: STRAWBEES!

We choose to cut the straws in half to make a more compact geometrical pattern and since the straws were 24 cm long we measured them and cut them at the middle (12cm)

Start building your trellis with the strawbees. Build any shape and size you want or need. The only rule you need to follow is that it needs to be at least a little bit flat if you want to be able to mount it to a wall.

We built ours with a geometrically and, kind of, symmetrical pattern that we liked.

Step 3: Laser Cut and Assemble Wall Mounts

When we had the overall shape of the trellis we made the wall mounts. The reason for not starting with them was that we wanted to see how big the trellis would be and be able to estimate how many wall mounts we needed and where to place them.

The mounts were laser cut out of 4mm clear acrylic plastic.

You will need to adjust the settings for your laser according to what works for you. The Illustrator (wall_mount.ai) file is colour coded, the black lines are for cutting through the plastic, the red square are engraved and so are the green lines. The reason for this is to make a hollow space for the RGB LED to fit underneath the mount. The green lines are for wires.

The first picture shows the three parts of each mount with the protective plastic, remove this.

Then glue the parts together, start with the round base plate, the un-engraved side up, add some glue and press the smaller of the two triangles down. Fitting it's small legs in the square holes. Then add some glue in the other square holes and the slit and press down the larger triangle.

wall_mount.ai
Download

Step 4: Soldering LEDs

Now comes the tricky part, soldering the LEDs. Depending on how many and how big your trellis will be this may take a while. There are a few things to think about!

The LEDs have a front and back, shown by small arrows and the text GND, DI/DO and +5v
GND = Ground (the "minus" side of a battery)
DI = Digital Input,
DO = Digital Output,
+5V = Voltage in (the plus side of a battery)

Since the LEDs have a front and back they must be connected correctly or they will not work. On the first LED the +5v on the DO side should be connected to the +5v on the next LEDs DI side.
The DO of the first LED goes to the second LEDs DI and the GND on the first LEDs DO side goes to DI side on the second LED.

Check out Adafruits NeoPixel überguide to get all the info

https://learn.adafruit.com/adafruit-neopixel-uberg...

MEASURING

Decide where you want the wall mounts to be on the trellis and measure the distance between them so you know how long the wires between the LEDs should be. When you measure Zig-zag and follow the strawbees and add a little extra length to run the wire up from behind the wall mount and down to the next. We hid the wires on the back of the straws and had them follow the trellis till the next mount. (Check next steps for pictures)

SOLDERING

The enamelled wire we used needs to be stripped of it's insulation and this is easily done with the soldering iron and some solder. It is also a good way to prepare the ends of the wire by coating them with tin.

Just heat up your soldering iron, wipe it of on a damp sponge to remove oxides, and then melt a little solder to form a pearl of solder on the tip of the iron.

Then press the tip down on the end of the wire as in picture 1, heating the wire and evaporating the insulation. Then while pressing the wire down with the soldering iron gently pull the wire so that the end get coated by tin. (picture 2). We usually do this against a piece of scrap wood or MDF to keep the work area nice and clean.

Now it's time for the LEDs. Start by wiping of your soldering iron again, make a new small drop of solder and press it against one of the contact areas on the LED. It's the copper coloured parts as seen in picture 3.

Let the solder flow out on the contact area, when it forms a nice shiny drop that sticks to the LED it's done.

Wipe your soldering iron again and make a new but tiny drop solder, press the tinned tip of the wire to the tin drop on the LED and heat up both the wire and the tin on the LED to fuse them together.

Now you are done, with the first one...

Continue doing this for all the LEDs you need or want

Step 5: Testing, Testing...

Ok, so now all the LED are soldered together, before we attach them to the wall mounts we need to test that they work.

Connect the GND to the Arduino GND, the +5V to the Arduinos +5V pin
and the DI to a digital pin on the Arduino board, for some reason we shan't specify, it's digital pin 6.

First you need to get the NeoPixel Library for Arduino (once again check out the Überguide

https://learn.adafruit.com/adafruit-neopixel-uberg... )

Connect the Arduino to your computer, open the Arduino IDE and open the exampel file from the NeoPixel Library called Strandtest. Read through the sketch and change the number of LEDs to whatever number you have. Then compile and upload it to the Arduino.

You should now have blinking colourful lights, if not something is wrong...

Debugging:

Check that everything is firmly connected and connected to the right pins.

If one LED isn't lighting up but the ones next to it are, check the soldering.

If the strand lights up close to the Arduino but the end of the LEDs don't light up, check the number of LEDs you are using and the number in the program. They need to match. If they do check the soldering on the last lit up LED and the first one that isn't lit up. Also check that the LED are facing the right way.

Step 6: Mount the LEDs on the Mounts.

Use the glue gun to glue the LEDs to the engraved hollow space. Be sure you use clear glue since you want the light to shine through the glue and the wall mount.

When done press the wall mounts through the holes in the strawbees (picture 4)

Turn the whole trellis upside down and glue down the wires to the straws and strawbees (picture 5).