FujiNet-5200-Rev0

Fujiversal-Atari2600 Rev1

All-in-one Atari 2600 FujiNet cartridge, the RP2354A successor to the RP2040 Rev0 (branch atari2600-rev0). It is the hardware for the 2600 bring-up in fujinet-firmware (branch 2600-experiment, worktree ~/Workspace/fn-2600).

• RP2354A (RP2350A + 2 MB flash in one QFN-60) runs the cart firmware (pico/atari-2600, board fujivcs, ported to the RP2350 as listed below). The cartridge port goes straight to the RP: A0-A12 on GP2-GP14 and D0-D7 on GP15-GP22, exactly as include/vcs_pins.h. RP2350 GPIO0-25 are "Digital IO (FT)": 5.5 V-tolerant while IOVDD is 3.3 V, and a 3.3 V high clears the 6507's TTL VIH (2.0 V). No '245 buffers and no direction pin: the firmware's per-access output enable is the only direction control.
• ESP32-S3-WROOM-1-N16R8 runs the fujiversal-atari2600 build of fujinet-firmware and is the RP's USB host (S3 IO19/IO20 -> 27R -> RP USB; the RP enumerates as CDC, VID 0xCafe). There is no UART between the chips.
• USB-C: power + CP2102N UART with UMH3N auto-program (flashes the S3).
• microSD (push-push, SPI on IO38-41, card-detect IO42), on the right edge.
• WS2812B-2020 status LED (IO48, on +5V) and a red RP activity LED (GP25).
• Buttons: RESET (resets both chips: the way back to the browser), BOOTSEL (RP), S3 EN, S3 BOOT. The S3 can also force the RP into reset or BOOTSEL itself (IO4 -> RUN, IO5 -> QSPI_SS, active low through 1k).
• Console 5 V sense on GP27 (100k/150k, 3.0 V at 5 V): the firmware can tell a powered console from a USB-only cart.

4 layers, fully routed, DRC clean with schematic parity, JLCPCB fab + assembly files in exports/jlcpcb/. Everything is generated from tools/design.py (circuit), tools/sch_layout.py (schematic drawing) and tools/placement.py (layout): edit those, never the KiCad files.

Pin contract

ESP32-S3 pins are exactly include/pinmap/fujiversal-atari2600.h: SD CS 41, SCK 39, MISO 40, MOSI 38, CD 42 (10k pull-up), LED strip 48, UART0 43/44, RUN 4, BOOTSEL 5, USB host 19/20. tools/check_nets.py checks all of this against the firmware headers (290 checks).

Edge connector

2x12 gold fingers at 2.54 mm pitch, 1.5 x 7.0 mm, starting 0.5 mm from the edge; tab 32.4 mm with 45-degree shoulders (geometry and orientation from the FujiPlusCart prototype gerbers, ../FujiPlusCart-Prototype).

The port carries no R/W, clock, chip select or reset: A12 is the only decode.

Schematic

Root + four wired sheets, drawn left to right in signal-flow order (docs/Fujiversal-Atari2600-Rev1-schematic.pdf):

1. edge-rp2354a: the edge connector on the left, the RP2354A beside it (mirrored so its GPIO column faces the edge): A0-A12 and D0-D7 are 21 straight wires from finger to pin. Supplies and Raspberry Pi's core regulator across the top; clock, RUN/BOOTSEL, USB and SWD leave on the right.
2. esp32s3-sd: EN/BOOT in on the left; UART, USB, SD and LED out on the right.
3. usb-uart: USB-C -> ESD -> CP2102N -> UART + auto-program.
4. power: console 5 V (and its sense divider) and VBUS -> +5V -> buck and RP LDO.

Nets cross sheets only on global labels at the page edges; every pin is wired or flagged no-connect. gen_sch.py lints each sheet (connectivity, overlaps) and checks the written schematic's netlist (kicad-cli) against design.py net by net.

Power

• Console 5 V (finger 23) through an AO3401A P-FET (gate = VBUS): fully on without USB; with USB in, the gate is at VBUS and only the body diode is left, so USB never back-feeds the console. R19 (4.7k) holds the gate down against the SS34's reverse leakage. USB VBUS through an SS34. Both meet on +5V.
• +3V3 (AP63203 buck, 2 A): ESP32-S3, microSD, CP2102N.
• +3V3_RP (AP2112K LDO, 20 us start-up, ~16-40 mA): every RP2354A supply pin, including the core regulator's VREG_VIN and VREG_AVDD (through 33R), which the datasheet asks to rise together. The pads are 5 V-tolerant only while IOVDD is powered; the LDO rises with the console rail, the buck's soft-start would not.
• DVDD 1.1 V from the RP's own regulator (3.3 uH AOTA, Raspberry Pi's minimal-design corner layout).
• Budget (estimate): ~60 mA idle and ~350 mA during WiFi TX on +3V3, about 250-300 mA peak from the console's 7805. Measure on a 2600 Jr before relying on console-only power.

Layout

• Board: 54.4 x 88 mm, 1.6 mm, Rev0's outline (same shell). Parts only above y 90.5 (the shell bottom, 25.5 mm above the contact edge).
• Stack (4 layers): F.Cu signals + GND pour / In1 GND plane / In2 +3V3 plane with a +3V3_RP island under the RP and its decoupling and a DVDD island (+ lobe) under its core / B.Cu signals + GND pour. Inner planes stop 9 mm from the insertion edge; the finger strip is a rule area (fingers only).
• Placement: the RP2354A at rotation 90, so A0-A9 sit on its south side in the order of the B.Cu address fingers below it; the data lines (D1-D7 at its north-east corner) run north-about and down the west corridor to the data fingers, so the two buses never cross. The core-regulator corner is Raspberry Pi's own RP2350A minimal-design layout (MIT), grafted at the RP and turned with it. The ESP32-S3 sits top-left with its antenna flush with the top edge over a band that is copper-free on every layer; microSD on the right edge, USB-C on the top edge (its shell face 0.45 mm past the edge, HRO's recommended PCB-edge position), power at the bottom right, buttons on the left edge.
• Rules: 0.2 mm / 0.15 mm default (0.5 mm power, 0.3 mm VBUS, 0.25 mm USB), 0.6/0.3 mm vias (0.5/0.25 under the RP), 0.25 mm copper-to-edge, 0.125 mm annular, 0.12 mm clearance floor for the neck-downs at 0.4 mm pitch. JLCPCB multilayer minimums: 0.09 mm track/space, 0.25/0.15 mm via.
• Shell: case/ (see case/case-spec.md), two options, both driven by case/board-anchors.scad (generated from the placement): a clamshell over the board's top with the tab bare (Fujiversal-Atari2600-Shell.scad), or a full-size cartridge re-modelled from norm8332's "Easy Print" 2600 shell (Fujiversal-Atari2600-CartShell.scad).

Flashing

• ESP32-S3: USB-C (CP2102N, auto-program): pio run -e fujiversal-atari2600 -t upload.
• RP2354A, first time: the RP's USB goes only to the S3, so use the SWD pads (TP1 SWCLK, TP2 SWDIO, TP3 GND) with a Raspberry Pi Debug Probe: openocd -f interface/cmsis-dap.cfg -f target/rp2350.cfg -c "adapter speed 5000; program fujivcs.elf verify reset exit".
• Afterwards: the S3 puts the RP in BOOTSEL (mailbox doorbell, or IO5 low across an IO4 pulse) and writes it over PICOBOOT; by hand, hold BOOTSEL and press RESET.

Firmware changes this board needs (not made here)

On fujinet-firmware 2600-experiment:

1. An RP2350 board for the cart (e.g. boards/fujivcs2354.cmake/.h): PICO_PLATFORM rp2350, boards/pico2.h-style header, 2 MB flash (stacked).
2. vcs_pins.h / main.c: drop DIR_PIN (GP26 is unconnected here); keep the output-enable drive/release; give D0-D7 more than the 2 mA drive they had when they only faced a '245 (they now drive the console bus).
3. Turn the bus pins' pulls off (RP2350 erratum E9), and pick an RP2350 clock (the 250 MHz / 1.15 V RP2040 setting does not carry over as is).
4. Use GP27 (VSENSE) to idle the bus server while the console is off.
5. Enable the 1200-baud BOOTSEL reset (pico_usb_reset + PICO_ENABLE_USB_RESET_VIA_BAUD_RATE=1) for the S3's PICOBOOT path.
6. ESP side: pico_* keys + CONFIG_USB_PICOBOOT_HOST_ENABLED in platformio-fujiversal-atari2600.ini, and the missing data/webui/config/fujiversal-atari2600.yaml.

tools/check_nets.py prints NOTE lines for 1 and 2 until they are done.

Ordering (JLCPCB)

• PCB: 4 layers, 1.6 mm, ENIG, gold fingers: yes, bevel 30 degrees, upload exports/jlcpcb/Fujiversal-Atari2600-Rev1-gerbers.zip.
• Assembly: Standard PCBA (gold fingers need it), top side only: BOM-JLCPCB.csv + CPL-JLCPCB.csv (82 parts). The board is narrower than JLC's 70 mm single-board minimum, so let JLC add the edge rails (not on the finger edge). Three fiducials are on the board.
• CPL: rotations and origins are corrected per footprint against the EasyEDA footprint of each LCSC part (tools/audit/jlc/jlc_rotations.json; ESP32-S3 origin +3.62 mm, USB-C -1.41 mm). Check pin-1 marks in JLC's placement preview anyway.
• Via-in-pad: the RP2354A and CP2102N exposed pads carry thermal vias. Choose epoxy-filled and capped vias if offered at a sensible price.
• Stock (2026-10-06): every part in JLC stock; 17 extended parts.

Regenerating

KiCad 10.0.6, Python 3 (numpy), Java + Freerouting 2.4.1 (~/.local/share/freerouting/freerouting-2.4.1.jar), the firmware tree at ~/Workspace/fn-2600 (or $FUJINET_FIRMWARE). tools/build_all.sh runs the schematic stage; LAYOUT=1 tools/build_all.sh adds the board (about 12 minutes):

python3 tools/harvest_symbols.py   # stock KiCad symbols -> tools/symcache.sexpr
python3 tools/make_edge_fp.py      # 2x12 finger footprint
python3 tools/make_fp_extra.py     # SOT-23-5, fiducial
python3 tools/gen_sch.py           # design.py + sch_layout.py -> root + 4 wired sheets; netlist parity
kicad-cli sch erc --severity-all --exit-code-violations Fujiversal-Atari2600-Rev1.kicad_sch -o /dev/null
python3 tools/check_nets.py        # netlist vs the fn-2600 firmware headers
python3 tools/gen_pcb.py           # outline, placement, RP regulator graft, plane islands, fan-out, rules
bash tools/route_board.sh          # Freerouting, A* finisher, tidy, GND stitching, 3D models, silk, DRC gate
python3 tools/export.py            # BOM, JLC BOM + CPL, gerbers, schematic PDF, SVGs, renders

Audit (kicad-happy)

docs/design-review-rev1.md is the datasheet-backed review (schematic + PCB). analysis/ (gitignored) holds the analyzer runs and analysis/deep_review.json; tools/audit/ holds the computations it cites (margins.py), the deep-review generator, the PCB audit runner and the JLC rotation table. .kicad-happy.json records the intentional findings and why.

python3 <kicad-happy>/skills/lcsc/scripts/sync_datasheets_lcsc.py Fujiversal-Atari2600-Rev1.kicad_sch
python3 <kicad-happy>/skills/kicad/scripts/analyze_schematic.py Fujiversal-Atari2600-Rev1.kicad_sch --analysis-dir analysis/
bash tools/audit/run_pcb_audit.sh  # PCB, cross, EMC, thermal, SPICE, gerbers, summary
python3 tools/audit/make_deep_review.py && python3 <kicad-happy>/skills/kicad/review/scripts/deep_review_gate.py analysis/deep_review.json --analysis-dir analysis/

Status

Rev1, generated 2026-10-06. Not built or tested on hardware.

Bring-up checklist (not verifiable in CAD)

1. Fit in a real 2600 (heavy sixer, 4-switch, Jr, 7800): fingers seat, shell clears the slot surround. For the cart shell, measure an original cart's edge recess first (edge_recess, see case/case-spec.md).
2. Console 5 V at finger 23 under WiFi bursts, especially on a Jr.
3. Power-up: scope +3V3_RP against CONS_5V at console power-on (IOVDD must lead the bus).
4. Bus timing: address -> data at the edge against the 6507 read window (~500 ns budget); D0-D7 must be released before the address changes.
5. Back-power: USB-C only, console off: the console must stay dead.
6. RESET returns to the browser; BOOTSEL + RESET enumerates the RP (VID 0x2E8A) on the S3.
7. VSENSE reads high with the console on, low on USB only.
8. microSD card-detect polarity on IO42, then set PIN_CARD_DETECT.
9. WiFi RSSI inside the shell (antenna flush with the edge, reduced side clearance).
10. JLC placement preview: pin-1 marks on every IC, LED and diode.

Provenance and license

CERN-OHL-W-2.0.

• RP2350 core-regulator corner (parts placement and copper): Raspberry Pi RP2350A minimal design (RPI-RP2350A-MINIMAL_R4-S1, MIT, tools/RPI-MINIMAL-LICENSE.txt), the layout the RP2350 datasheet (6.3.8) says to follow.
• Edge geometry and orientation: the FujiPlusCart prototype in this repository (via Rev0's make_edge_fp.py).
• Generator pipeline: NES/FujiNet-NES-Rev0/tools (schematic drawing, routing tools), with Rev0's 2600 outline and checks.
• Cartridge shell (case/Fujiversal-Atari2600-CartShell.scad): re-modelled from "Atari 2600 Cartridge Shell - Easy Print" by norm8332 (https://www.thingiverse.com/thing:1790785, Creative Commons Attribution); changes listed in the file header and case/case-spec.md.
• Symbols and footprints: official KiCad libraries (CC-BY-SA 4.0 with exception), Raspberry Pi's RP2350A footprint, the TF-015 footprint from LCSC/EasyEDA; 3D models listed in 3d/README.md.

Files