Pico Macro Keyboard Design

K

killacam7300

Fresh-place the entire Pico Macro Keyboard PCB from scratch on a 100 mm × 100 mm rounded-rectangle 4-layer board.
Top side priority:
Keep the top side clean and user-facing.
Place the mechanical key switches in a regular macro-keypad grid with consistent row/column spacing and aligned orientation.
Keep the RGB LEDs visually associated with their corresponding switches and avoid crowding the key grid.
Place rotary encoders and any user-facing controls on the top side in ergonomic positions near the key grid.
Place mounting holes near the board corners and keep them clear of switches and encoders.
Bottom side priority:
Place the Raspberry Pi Pico / MCU module and the majority of supporting electronics on the bottom side.
Group the MCU, flash, crystal/oscillator, regulator/power parts, reset/boot circuitry, USB/support passives, and decoupling capacitors by function.
Keep decoupling capacitors close to their associated IC power pins, crystal/load caps close to the MCU oscillator pins, and power components clustered together.
Minimize estimated routing distance between the bottom-side MCU and the top-side switches, LEDs, and encoders.
Prefer moving support passives on the bottom side rather than contaminating the top-side visual layout.
Placement quality goals:
Resolve overlaps, keep all components inside the board outline, preserve routing channels between the key grid and MCU area, and maintain clean edge/corner clearance.
Use both layers intentionally: top for human-interface components, bottom for dense electronics.
After placement, run DRC/review and report any remaining overlap, off-board, or layer-assignment issues.

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USB edge access
Mounting clearance
Top switches only
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Fresh Placement Execution Plan — Pico Macro Keyboard PCB
Scope
Fresh-place the existing Pico/RP2350 macro keyboard design on a 100 mm × 100 mm rounded-rectangle, 4-layer PCB. Preserve a clean user-facing top side while using the bottom side for the MCU and most supporting electronics.
Starting Observations
  • Board setup is already 100 mm × 100 mm, 4 copper layers, rounded rectangle with ~7 mm corner radius.
  • Current placement contains multiple off-board/out-of-bounds items and a Raspberry Pi logo/graphic with an extremely large bounding box. Reset/remove/resize decorative graphics before placement work.
  • Current review shows many airwires, several overlapping-copper errors, missing MPNs for many generic passives/templates, floating-pin warnings, and one unannotated PCB/graphic item.
Placement Strategy
  1. Mechanical frame first
    • Treat board origin as the board center and keep all functional components inside approximately x/y = ±47 mm, with extra clearance in rounded corners.
    • Place mounting standoffs/holes H1–H4 near corners, nominally around (±43 mm, ±43 mm), with copper/component keepouts and screw-head/washer clearance.
    • Place USB-C connector J1 on the rear/edge of the board, flush to the edge, with mechanical insertion clearance.
  2. Top-side user interface
    • Keep top side clean: switches, per-key RGB LEDs, rotary encoders, slider/potentiometer, visible status LED/light pipe only as required.
    • Arrange the 12 Kailh Choc switches SW2–SW13 in a regular 3 × 4 macro-keypad grid using consistent pitch, rotation, and keycap clearance.
    • Place one WS2812-2020 LED U4–U15 associated with each key, centered or optically aligned to its switch/diffuser position, all with consistent orientation and a sequential data-chain path.
    • Put switch diodes D2–D13 on the bottom side directly below/adjacent to their corresponding switches where possible to keep the top side visually clean while keeping matrix loops short.
    • Place rotary encoders SW14 and SW15 ergonomically near the grid, preferably along the right side or upper-right area, with knob/shaft keepouts and enough finger clearance.
    • Place RV1 where user-accessible and mechanically supported, preferably along the top or side edge depending on desired slider direction.
  3. Bottom-side functional electronics
    • Place U1 RP2350A on the bottom side roughly under the center of the switch/controls cluster to minimize fanout distance to rows, columns, LED data, encoders, and slider signals.
    • Group U3 flash and its capacitors C19/C20 immediately adjacent to U1 QSPI pins. Keep QSPI traces short and direct.
    • Group Y1 crystal, C15/C16, and R7 immediately beside U1 XIN/XOUT pins. Keep this area isolated from USB, LED data, and switching-regulator nodes.
    • Ring U1 with local decoupling: place C1–C6/C10 at +3V3/IOVDD-related power pins, C7–C9/C13 at +1V1/DVDD/VREG-related pins, and C11/R1/R2 for ADC_AVDD near the analog supply pin.
    • Place regulator/power input group close to USB entry but not under sensitive clock/ADC routes: J1 → D1 → C18/VSYS → U2/L2/C17 → +3V3 distribution. Keep L2 tight to U2 LX pins and high-current loops compact.
    • Place Q1/R15/R16/R17/C21 GPIO29/VSYS sense or control group near U1 ADC/control entry, away from L2 and WS2812 data.
    • Place reset/boot/user button SW1, boot/run/passives, SWD header PROG, R4/R6, status LED LED1/R18, and USB passives R3/R10/R11/R12 by function and accessibility.
    • Place encoder debounce networks R20–R22/C22–C24 near SW14 and R23–R25/C25–C27 near SW15, on the bottom side under/near each encoder but clear of mechanical tabs.
  4. Layer-use intent
    • Top copper: short local switch/LED connections where necessary, minimal visible routing, optional ground pour where it does not affect appearance/LED optics.
    • Inner layer 1: continuous GND reference plane with stitching near U1, LEDs, USB, regulator, and mounting holes.
    • Inner layer 2: +3V3/VSYS distribution and selected low-speed signal escapes as needed; keep regulator switching node local only.
    • Bottom copper: main routing layer for MCU fanout, matrix rows/columns, QSPI, USB, encoder/slider/support signals, and dense passives.
  5. Routing priorities after placement
    • Route power entry and regulator current loops first.
    • Route U1 decoupling and crystal next.
    • Route USB DP/DM as a short matched differential pair through R3/R10.
    • Route QSPI flash short and compact.
    • Route matrix rows/columns with regular channels and short diode connections.
    • Route WS2812 data in physical chain order U4 → U5 → … → U15 and provide robust LED power/ground rails.
    • Route encoders, slider, reset/boot, SWD, and status LED last, preserving analog/clock quiet zones.
  6. Cleanup and review loop
    • Resolve all component overlaps, off-board placements, and oversized silkscreen/graphic bounds before detailed routing.
    • Run DRC/ERC after rough placement, after critical routing, and after final cleanup.
    • Review and fix overlapping copper, airwires, floating pins/no-connect intent, missing designators, and missing MPN/manufacturing data before release.

  • Scope

  • Starting Observations

  • Placement Strategy