Deck

Phosphor Deck controller board

The circuit board for the Phosphor Deck: every knob, button, fader and pad on top, and the electronics that read them underneath. It is the board drawn on the schematics, and it runs the firmware in ../../firmware.

Rev A has not been made yet. It passes KiCad's design-rule check with no errors and no unconnected pins, but nobody has held one. Build the breadboard test in the firmware's README before ordering.

What to send a board house

Everything is in fab/:

• gerbers.zip — the board itself: two copper layers, 296 × 234 mm, 1.6 mm.
• bom.csv — every part, grouped, with the part to buy where there is one.
• positions-bottom.csv — where each surface-mount part goes, for a house that assembles the underside.
• jlc-bom.csv and jlc-cpl.csv — the same parts and places in the exact form JLCPCB asks for, with their LCSC part numbers.

The board is laid out so that a board house only has to assemble one side: every surface-mount part (chips, resistors, capacitors, LEDs, the Pico 2) is on the bottom. Everything on top is through-hole and soldered by hand: 61 switches, 10 knobs, 8 faders, the 16 pad sensors' tabs and the pedal header.

Ordering from JLCPCB, step by step

JLCPCB makes the board and solders every part on the underside for you. You then solder the top parts by hand.

1. Upload the board. On jlcpcb.com, choose Order now and add fab/gerbers.zip. It reads the size (296 × 234 mm) and the two layers by itself.

2. Choose the board options. Layers 2, thickness 1.6 mm, FR-4. Five boards is the smallest order. Green is the cheapest colour; any colour works. For the surface finish, lead-free HASL is fine; ENIG costs more and gives flatter pads. Leave the rest as it is.

3. Turn on PCB Assembly. Choose:

   • PCBA type: Standard. Economic is cheaper, but it is meant for one side, usually the top, and JLC sells the Pico 2 for Standard only. If Economic offers Bottom Side when you order and you will solder the Pico yourself, Economic works too.
   • Assembly side: Bottom Side. Every machine part is underneath.
   • Assembly quantity: 2 or more; it can be fewer than the boards.
   • Let JLC add the edge rails, fiducials and tooling holes if it asks. Standard assembly needs them and the board has none of its own.
   • Tick Confirm parts placement: for a small fee, one of their engineers checks the placements and asks you before building.

4. Upload the two parts files: fab/jlc-bom.csv as the BOM and fab/jlc-cpl.csv as the CPL (the placement file). Every line should match a part. If one is out of stock, pick a part with the same value, rating and size, or wait.

5. Check the placement preview. It shows each part on the board, seen from underneath. The files already turn each part the way JLC's drawings need, but look at each kind once:

   • the chips (U1–U16): the dot that marks pin 1 sits on the board's pin-1 mark;
   • the LEDs (D1–D42): the LED's cut corner matches its outline, and the body sits over the light hole;
   • the big capacitor (C79): its + side sits on the + pad;
   • the Pico 2 (U15): its USB socket is at the same end as on the board drawing.

   The small resistors and capacitors can sit either way round. If a part is wrong, select it and turn it in the preview, or change its Rotation in jlc-cpl.csv and upload it again.

6. Solder the top by hand when the boards arrive: the 61 switches, 10 knobs, 8 faders, the 16 pad sensors' tabs and the pedal header. If you left the Pico 2 off the order (mark it do not place on the parts page), solder it underneath by its edge pads.

The board is larger than 650 cm², so JLC adds a large-board fee to the assembly. Basic parts need no loading fee in an Economic order; in a Standard order every kind of part has a small one.

Things to know before ordering

• The LED light holes. The LEDs sit underneath and shine up through small holes. KiCad's own footprint for them puts their pads 0.25 mm from the hole's corners; the rest of the board keeps 0.3 mm. Most board houses accept this for internal cutouts — ask yours.
• The buttons are 6 × 6 mm tactile switches under printed caps, because the panel's buttons sit closer together than keyboard switches allow. Pick the switch height that meets your caps through the top plate.
• The faders are centred at 167 mm, 2 mm lower than the first panel drawing: a PTA4543's body is 60 mm long. The top plate's slots run from 143 to 191 mm.
• Lights on narrow buttons are dots. The transport and function buttons are too narrow for a light inside the cap, so theirs sits just above as a dot in the top plate.
• The Pico 2 is soldered flat by its edges on the underside. Its USB socket points along the board, so use a right-angle micro-USB cable to the Raspberry Pi.

Making it again

The board is generated, not drawn: generate.py places every part from the panel drawing and wires it from firmware/deck-layout.json, Phosphor's own control table, so the board, the firmware and the app share one table. route.sh runs the lot — placement, routing with Freerouting, ground pours, the design-rule check, and the files in fab/:

KICAD=/Applications/KiCad/KiCad.app \
FREEROUTING=freerouting-2.4.1.jar \
JAVA=<a Java 25 runtime>/bin/java \
./route.sh

It needs KiCad 10 and Freerouting 2.4, which needs Java 25. Routing takes about five minutes a try. The router's result varies a little from run to run and now and then leaves a connection unrouted, so the script tries up to three times and writes fab/ only from a board with no errors and nothing unconnected; drc.rpt is the check that board passed. A ground fill covers both sides, tied together by stitching vias wherever one fits.