Seedbox wiring · v0.1

One stripboard carries the Pico and the MIDI circuits. Everything on the panel (screen, encoder, pots, buttons, jacks) connects to it with hookup wire. Board positions are given as strip letter + hole number, e.g. X2 is strip X, hole 2, counted from the left with the parts facing you.

Wire map · panel to board

Every panel wire, where it lands. Big blue text is the board hole: strip letter, then hole number counted from the opto end (the end away from the Pico's USB).

DonePartLugWireBoard hole

Ticks are saved in this browser. Lug drawings for each part are under Panel wiring further down.

Wire colours

Red · 3.3 V and the MIDI OUT supply pins Black · ground Yellow · button rows, SEED, RUN Green · button columns, encoder Blue · screen, pots, MIDI signals Grey · short links on the board

If your five spools are other colours, keep the roles and rename them. Red and black for power and ground matter most; the rest just keep bundles readable.

Board · parts side

Copper strips run left to right underneath (shown faintly). Board size 34 holes × 28 strips (about 86 × 71 mm). The Pico sits in two 20-pin female headers with pins 1 and 40 on strip A, so its USB end is flush with the top edge of the board and the micro-USB plug reaches out past it: line that edge up with a slot in the box wall. Numbered dots P1… (pads) are where off-board wires solder; the wire map at the top says where each one goes.

Board · copper side, for cutting

Track cuts

    This view is flipped: hole 1 is on the right. Cut with a 3–4 mm drill bit twisted by hand or a spot-face cutter, then check each cut with the meter's continuity beeper.

    Power strips along the bottom

    • Z · 5 V from the Pico's VBUS (only the opto uses it)
    • AA · ground
    • AB · 3.3 V from the Pico's 3V3 pin

    Every red wire to the panel starts on AB, every black wire on AA (or on the AGND strip for the pots).

    Board parts and links

    PartValueHolesNote

    Off-board wires

    #Board holeColourPico pin / signalGoes to

    Panel wiring

    Button matrix · seen from the back

    Each button: one lug to its row wire (yellow, daisy-chained along the row), the other lug through a diode to its column wire (green, daisy-chained down the column). The diode's band points to the column. Solder the diodes straight onto the button lugs and sleeve them. 11 track buttons, each with its own diode, plus D1 on the board: 12 diodes. GHOST is wired at row 2 / column 4 (where FILL used to be). The RUN toggle sits in the grid's row 1 / column 4 spot but is not part of the matrix: row 1's wire stops at SNARE. The drawing is from behind the panel, the side you solder on: KICK is top-right, RUN top-left.

    MIDI jacks · 3.5 mm TRS, Type A

    • MIDI IN: ring → Y1, tip → W1. Sleeve stays empty.
    • OUT KIT: tip → X26, ring → V22, sleeve → AA22.
    • OUT SYNTH: tip → U31, ring → V31, sleeve → AA31.

    Use stereo (TRS) jacks; mono ones have no ring. Lug order differs between jack models, so find the tip, ring and sleeve lugs with the meter and a plug inserted. Type A is the MIDI standard: a plain stereo 3.5 mm cable goes straight to another Type A device (e.g. SP-404MKII). A DIN device (e.g. MiniFreak) needs a TRS-to-DIN adapter that says Type A; a Type B one swaps tip and ring and gives silence (nothing breaks).

    Nokia 5110 module

    • Pin order as printed on your module: 1 VCC, 2 GND, 3 SCE, 4 RST, 5 D/C, 6 DN (MOSI), 7 SCLK, 8 LED.
    • LED (backlight): wire it through a 330 Ω resistor to AB22 (3.3 V); put the resistor inline at the module end and sleeve it. On boards with this pin order that lights it. If it stays dark, move that wire to any free hole on strip AA (ground). GP22 (L27) is left free: it's only needed if you ever want dimming, through a transistor.
    • SCE can go straight to ground instead of S27 if it's the only thing on the SPI bus; that frees GP17.

    Encoder module

    Pin order as printed on your module: VCC, GND, SW, SIB, SIA. Power it from 3.3 V (AB4), never 5 V: its pull-up resistors would put 5 V on the Pico's pins. If turning it clockwise steps the wrong way, swap SIA and SIB (or flip it in firmware).

    Pots, SEED, RUN

    • Pots, lugs facing down, shaft toward you: left lug to AGND (H27), middle to its pin, right lug to 3.3 V (AB25). Chain the left lugs together and the right lugs together.
    • SEED: one lug to Q2, the other to the ground bus (AA6).
    • RUN: middle lug to S2, one outer lug to the ground bus. If RUN and STOP come out swapped, use the other outer lug.

    Build order and checks

    Board

    1. Cut the board to 34 × 28 holes. For the top edge, cut through the row of holes above strip A, then sand it back to about 1.3 mm from the strip A holes (stop before the strip A copper). That puts the Pico's edge flush with the board; unsanded, the Pico sits about 1 mm back, which still works if the wall slot lets the plug's moulding through. Make the track cuts and beep each one out.
    2. Solder the two Pico headers, the DIP-8 socket (notch toward strip U), then the resistors and the diode (band on V4). Leave C1 for step 4.
    3. Solder the grey links with insulated wire. The two long ones (GP0 and GP4) run straight down under the Pico, between its two headers: fit them before the Pico goes in.
    4. Before fitting C1, with the Pico and the 6N137 out: AB to AA must not beep, Z to AA must not beep. Then fit C1 (it can chirp briefly on the beeper once it is in).

    First power

    1. Plug in the Pico only, power from USB. Measure AB to AA: about 3.3 V. Z to AA: about 5 V.
    2. Unplug, insert the 6N137 (notch toward strip U, pin 1 at hole U5).
    3. Wire the panel. Before closing the box, check that no bare lugs touch each other.
    4. The box needs the Pico firmware (the C port of this simulator) before it does anything. That's the next step. Firmware note: GP0 and GP4 drive the MIDI loops directly (about 6–8 mA), above the RP2350's default 4 mA drive, so set them to 8–12 mA with gpio_set_drive_strength().