UNTZtrument: a Trellis MIDI Instrument

published June 20, 2014, last edited March 27, 2024

posted in LEDs/ LED Matrices Microcontrollers Trellis/ Classic Trellis

Beginner

Project guide

Assemble Case

You should have a tested and fully working Trellis (without case) at this point. Don’t proceed until you’ve reached that milestone.

Start by peeling the backing paper off both sides of all the laser-cut parts. It’s easiest to start at a corner, catching the edge of the paper with a fingernail.

The laser-cutting process sometimes leaves a little paper soot at the edges. If you like, you can wash these off with soap and water, just be absolutely certain that all the parts are completely dry before proceeding!

All told, there should be 13 laser-cut parts (15 for HELLA UNTZtrument). Most are clear except for the one black grid piece.

Your kit should also include the following hardware:

Eleven (11) nylon screws
Three (3) nylon nuts
Three (3) 1/8" board spacers
Four (4) 1" threaded standoffs
One set of 4 peel-and-stick rubber feet

HELLA UNTZtrument has 2 more standoffs and 4 more screws for the wider case.

If any parts are missing or damaged, contact [email protected] to arrange for a replacement.

You’ve already assembled and tested the Trellis and Arduino Leonardo boards; they’re implied but not listed in the above inventory.

We’ll start with the base piece…it’s one of the large squares, the one without the waffle grid.

This piece has the Arduino footprint scored on one face. This helps identify the top surface.

Turn the base over and install three screws in the Arduino footprint area.

This piece needs to be turned back over for additional work. You can either put a little masking tape over the head of each screw to hold them in place…or, if you’re dextrous, grip the three screws from the other side as you turn it over.

Set the base piece down so the screws are now pointed up.

Add a 1/8" nylon standoff over each screw.

Install the Arduino board with the mounting holes over these three screws (there’s a fourth hole, but we’re not using it here).

Add a nut to each screw. There will probably be some mechanical interference from nearby headers and parts…that’s okay, you just need to get the nuts started.

Now turn the base over, remove the tape (if used) and gently tighten the three screws with a small screwdriver.

The standoffs are easier, we can do them one at a time. No need for tape.

Insert a screw into one of the four corner holes. Come up from the underside, as you did with the Arduino. Catch the screw in the threads of the standoff and turn it into place. Finger pressure is usually sufficient, or you can gently use a screwdriver.

Repeat until all four standoffs are installed (six for HELLA UNTZtrument). You should then be able to set the base down with the Arduino and standoffs all on the top side.

Next we’ll install the vertical and horizontal braces.

The vertical braces (which run parallel to the Arduino’s longer axis) all look similar, but notice the “nubs” on the bottom are different: one, two, one. These fit into corresponding slots on the base. (On the HELLA UNTZtrument, there are five vertical braces — again, they’re keyed to only fit specific positions).

The horizontal braces now slot into notches on the verticals. Each of these is a different shape. The thinnest one is designed to clear the Arduino’s power jack. The slightly thicker (but still pretty thin) brace goes down the middle, while the full-thickness one is at the bottom.

The four side pieces are almost identical…except for one which has a notch for the Arduino’s USB port. Install this side first. Align the bottom tabs with the slots in the base and tilt it up into place. If the USB port is covered, you’ve got it backwards — turn it around and try again.

Once the first side is in place, the alignment of the remaining three should be straightforward.

Now get the Trellis board ready. Remove the rubber buttons for the time being and turn the board face-down.

Orientation is important. Once installed, the top edge of the Trellis will face be aligned with the Arduino’s USB port.

Insert the power and signal wires from the Trellis to the headers on the Arduino:

5V from Trellis to 5V on Arduino
GND from Trellis to any GND on Arduino
SCL from Trellis to SCL on Arduino (this pin is nearest the mounting hole with no screw through it)
SDA from Trellis to SDA on Arduino (this is the second pin, next to SCL)

The INT pin is not used for this project; no connection is necessary.

Now the Trellis gets turned over, LED side up, and is lowered into place in the case. You’ll see the horizontal and vertical braces have notches into which the board neatly fits.

The wires will fight you at this stage, either pushing back against the trellis or springing out of the Arduino sockets. This part goes a little easier if you bend a couple zig-zag kinks in the wires, keeping them all within that quadrant of the case. Be patient and put each wire back in place if they pop out.

If your wires are connected to a different location on the Trellis, that’s okay…the braces have notches to allow wires to run from quadrant to quadrant.

Once the Trellis is in place, you’ll probably need to hold it down as the wires press against it. This is normal.

While still holding this down, install the rubber button elastomers over the Trellis, aligning the “nubs” with the corresponding holes in the board. You’ll need to scoot these around a little until they all sit flush.

Install the clear top “waffle” piece. Since you’ll still be holding the Trellis down, start from one edge, aligning the notches with the tabs on the side pieces, and swing this down into place as you remove your other hand.

When everything is aligned and sits flush, you can place the black surface piece over this.