Parts & Tools
In this portion of the guide, we'll connect the components together. Before we start, be sure to get our workspace cleaned up. Gather up ours tools and heat up the soldering iron. Are you ready? Let's GO!!
I like to start every project by wiring up the slide switch. We'll need two pieces of wire to connect it to the Adafruit Feather. The length of them should be about the same length of the enclosure (3in or 10cm). It's OK if they're longer because you can trim them short later.
Before we connect the wires to the switch, it's a good idea to "tin" them. First, remove a bit of insulation from the tips of each wire using wire strippers. To tin a wire, apply the tip of your soldering iron to the wire for a second or two, then apply the solder to the wire. The solder should flow freely onto the wire and coat it. This helps prevent the strands of wire from fraying. Pro Tip: Secure the wires to the grabber of a pair of helping third hands to tin the four tip, one after the other.
Connect Wires to Switch
Now we need to solder the wires to the pins on the slide switch. We only need two of the three pins, so remove either the far left or far right pin (but not the middle pin). Then, tin the remaining two pins with solder. Next, attach the wires to the pins. Apply the tip of your soldering iron to the pin for a second or two, then touch the tip of the wire to the pin. Hold it in place for a second or two to allow the solder to solidify. Repeat this process for the second wire.
Switch for Feather
We'll be connecting the slide switch to the Feather board, but first we need to expand the voltage and ground pins. If we were to connect it now, we'd use up the only ground pin on the Feather. We have several components that need to connect to the voltage and ground pins, so we'll "expand" them by attaching some pieces of Flex PCB.
This Flex PCB is great for expanding pins. It's basically a thin half-sized breadboard. You can easily cut pieces using a pair of scissors. We'll only need two pieces, each with four available pins. Save the rest for future projects.
Tin Flex PCB
Tinning the pins on the flex PCB make it a bit easier to attach wires. Handling the flex PCB can be a bit of a hassle. I found using tweezers to hold it and then securing the tweezers to a set of third helping hands works nicely. This way the flex PCB is secured in place while you can solder up the pins.
Expand Power and Ground
Next, we can attach the pieces of flex PCB to the voltage and ground pins on the Feather. First, cut the pieces in two so they're separated. Tin the 3V and GND labled pins on the Feather. Then, set a piece of PCB over the pin. I recommend handling it with the tweezers. Now apply the tip of your soldering iron to the pin. Once it melts the solder, move the tip away and hold the flex PCB in place until the solder solidifies. Repeat this process for the second pin.
Connect Switch to Feather
Now we can connect the slide switch to the Feather. Solder one wire from the switch to the flex PCB connected to the GND labeled pin the Faether. The second wire from the switch needs to connect to the EN (enable) labeled pin. Once they're connect, we should be able to power the board on and off.
Test Switch & Battery
How about we test out the switch. Grab the battery and plug it into the Feather board. If the board turns on (red LED turns on), try flipping the switch to turn it off and vice versa. If the board stays off or on, the slide switch might be damanged or there's not enough solder. Once we're done testing the switch, disconnect the battery from the Feather board.
Wires for Cap Sensor
Next up, we'll make some wires for connecting the capacitive sensor to the Feather. These wires can be the same length of the enclosure (or same length as the switch wires). We'll need five wires in total. I used different colored wires to help tell them apart, but you don't have too.
Once our five wires are cut, it's time to strip and tin them! I managed to secure all five to a grabber on the third helping hands. This saves time from having to secure each wire to the grabber, one by one. Careful not to solder the wires together, though!
Heat Shrink Tubing
Managing a bunch of wires can be messy. I like to use heat shrink tubing to keep them bundled together. When heat is applied to it, it actually shrinks. Cut a piece of tubing and slip the wires through. Then, use the heating element (NOT THE TIP!!) from your soldering iron to apply heat. The tubing shrinks and tightly holds the wires together. Pretty neat, huh? You can do this for most of the wires in this project.
Wire Cap Sensor
Now we can connect the wires to the capacitive touch breakout board. I secured the PCB to a Panavise Jr to keep it sturdy while soldering in the wires. It's a good idea to tin the pins first. We'll need to connect the wires to VIN, GND, SDA, SCL, and IRQ labeled pins on the board. Doesn't matter which color goes where but I tend to keep them consistent (red for voltage/power and blue for ground).
Connect Cap Sensor To Feather
Next, we'll need to connect the wires from the cap sensor to the Feather board. I kept the cap sensor secured to the panavise and secured the feather to the third helping hands. You can follow the circuit diagram for reference. We'll connect the following things together.
- SCL from MPR121 to SCL on Feather
- SDA from MPR121 to SDA on Feather
- IRQ from MPR121 to A4 on Feather
- GND from MPR121 to GND on Feather
- VIN from MPR121 to 3V on Feather
NeoPixel to Feather
OK, now we have the cap sensor connected to the Feather. Awesome! Next, let's get that NeoPixel ring connected to the Feather.
We'll need three wires to connect the NeoPixel ring to the Feather board. They can be the same length as the before (length of the enclosure). Repeat the same process as before, measure, cut, strip and tin all three wires.
Solder Wires to NeoPixel
Next, tin the data-in, 5v power and ground pins on the NeoPixel ring. Then, solder in the three wires.
Connect NeoPixel to Feather
With our NeoPixel wired up, we can now connect it to the Feather board. Make the following connections.
- Data-In from NeoPixel to Pin #6 on Feather
- 5V Power from NeoPixel to 3V on Feather
- Ground from NeoPixel to Ground on Feather
In order to connect the capacitive touch sensor to our "touch pads", we need a way to connect wires to them. I found using copper tape was the most reliable way to do this. This copper tape has a sticky adhesive backing that is conductive, so we can stick it to our touch pads. Cut five short pieces using scissors.
Stick Copper Tape to Touch Pads (CNC Milled Only!)
OK, this next part is specifically for CNC milled touch pads. Since I milled my pads out of aluminum, I can stick the pieces of copper foil to them right away. If you've 3D printed the pads using conductive PLA, DO NOT DO THIS YET! You'll need to connect wires to the copper foil tape first, and then stick them to the plastic pads. I haven't tried, but I'm sure they'd melt if one were to tin the copper with them attached to the plastic pads. Either way, take note of which side the copper tape sticks too. It's the side with the noticeable lip.
Touch Pad Wires
Now it's time to make some wires for connecting the touch pads to the capacitive touch sensor. We have six pads, so we'll need six wires. Again, they can be the same length as before (length of the enclosure). Measure, cut, strip and tin the wires.
Connect Wires to Copper Tape
With our wires made, we can now solder them to the pieces of copper foil tape. I recommend tinning the copper foil first, and then solder the wires to them. If you've 3D printed the touch pads, you'll need to solder the wires to the stand-alone pieces of copper foil tape.
Wired Touch Pads
And now we have wires connected to the pieces of copper tape, yay! If you've 3D printed the pads, now's a good time to stick the pieces of copper foil tape to them. Remember to stick them to the side with the visable lip. Not the side with a flush surface!
Connect Pads to Cap Sensor
Now it's time to connect the wires from the touch pads to the capacitive touch sensor. It doesn't matter which pad goes where, as long as they connect from pins 0-5. If we get them mixed up, we can use a multimeter to determine which pad is connected to pin number 0, 1, 2 and so on.
And now we have completed our circuit! You can plug in the battery again to see if everything turns on. Though, I wouldn't test out the MIDI functionality yet because the touch pads might be touching (randomly triggering MIDI notes). So let's work on mounting the components to the encosure. On to the next page!