Interface Board

These directions are for the “Gen 2” Cupcade kit. Earlier Gen 1 kits had a DIY interface board. You probably don't have one of these unless you have a very old kit!
A small circuit board — specially designed just for Cupcade — features a joystick adapter circuit and a small audio amplifier. Just a few through-hole components need to be soldered.
Different parts will get soldered on opposite sides of this board. Labels and outlines (along with the photos here) should make it clear where parts are inserted.

But first…a few wires need to be cut to about six inches long. You don’t need a ruler for this…the ribbon cable is just the right length. Unplug it from the Pi and PiTFT and use it for reference.

This isn’t rocket surgery, don’t worry if wires aren’t precisely the right length. Six-ish inches is fine!
Cut two (2) wires about six inches long and strip about 1/4" of insulation from both ends.

24 gauge stranded wire is ideal. A little thicker or thinner is okay, as is solid-core wire…stranded is simply more flexible.

Color-coding the wires likewise isn’t essential; one color will suffice if that’s what you have.
Solder one end of these wires to the connection points on the speaker.

Optional: you can keep these wires together with a bit of heat-shrink tube if you like.
Cut the audio cable so it's a little longer than the ribbon cable.

Strip about 1" of the outer jacket only to reveal the three wires inside: two are insulated, the third is bare copper.
Strip 1/4" insulation from the two inner wires. Twist the stranded copper wire into a tidy bundle.

Some headphone cables have red and black wires rather than the red and white shown here. This is OK, it all works the same. Red is the right channel, black or white is the left channel, copper is ground.
That bare copper wire on the audio cable is a problem…it might contact metal parts in the vicinity. We must insulate!

Slide a small piece of heat-shrink tube a few inches down the cable (around the whole thing, not just the copper wire).

Slide a second piece of heat-shrink tube over just the copper wire and heat it up. This covers most of the wire, but there’s still a tiny gap.

Slide the first (un-shrunk) piece back up so it covers the gap, apply heat.
The four 2-pin JST sockets, plus the 5-pin joystick header, are inserted on the “CUPCADE” side of the board and are soldered on the back side.

It’s easiest to do the JST sockets first, one at a time. You can temporarily hold them with a little tape, or place each one “legs up” on the table and lower the board in place, then solder.

Notice how the two rows sit “back to back.” This makes it a little easier to unplug the connectors later.

The 26-pin Raspberry Pi header then mounts on the underside of the board, with the pins soldered on top. Make sure the notch on this header matches the outline on the board!
The speaker and headphone wires then connect to corresponding points on the board. The speaker wires go to the two “Spkr” points, headphone to the three “Audio” points: red wire to “R,” black or white wire to “L,” copper wire to “GND.”
Assemble the analog thumb joystick. Some of the pins may be a little bent from shipping and need to be nudged into place. The “hat” simply presses into place.

Install a 5-pin header from below.

Make sure all your solder connections are smooth and clean, like tiny Hershey’s Kisses®. There should be no solder balls or bridges, no gaps between pins and their corresponding pads.

Switch off your iron, all the soldering’s done now!

This guide was first published on Apr 04, 2014. It was last updated on Apr 04, 2014. This page (Interface Board) was last updated on Oct 09, 2019.