Status: In Review Project: Enigma-NG Author: Izzyonstage & GitHub Copilot Version: v.0.1.0 Last Updated: 2026-08-12

The Enigma-NG system uses a modular, museum-grade architecture built around a fixed Controller motherboard and two removable service modules: the Power Module and the Stator.

The design/Standards/Global_Routing_Spec.md applies to all boards except where a board-level design spec explicitly records an exemption.

Note: The Extension Rotor Stack block is shown in simplified form pending resolution of the extension-mechanical-usage architecture review. Once that topology is finalised, both this diagram and README.md will be updated to show the full Groups 2–6 detail.

flowchart BT
    REF["🔵 Reflector Board<br>Passive turnaround · 30-pin J4"]

    subgraph RSTACK["🔄 Rotor Stack  — up to 30 rotors"]
        subgraph G1["Group 1  (Rotors 1–5)"]
            ROT["Rotor Module ×5<br>EPM570 CPLD · FDC2114 sensor<br>10 wiring sets · 4-pos DIP"]
        end
    end

    subgraph STATOR["⚙️ Stator + Config"]
        STA["Stator Board<br>EPM570T100I5N CPLD · ENC routing matrix"]
        SET["User Settings Module<br>10× toggle · 12× RGB LED · MCP23017 ×3"]
        STA -. "I²C harness" .-> SET
    end

    subgraph PWR["⚡ Power Module"]
        PM["Power Module<br>PoE+ 802.3bt · USB-C PD · Battery<br>eFuse · Buck · LDO · Supercap UPS"]
    end

    subgraph ENCS["🔡 Encoder Modules  ×6"]
        KBD["KBD_ENC"]
        LBD["LBD_DEC"]
        PLG["PLG_PASS1_ENC · PLG_PASS1_DEC<br>PLG_PASS2_ENC · PLG_PASS2_DEC"]
    end

    subgraph CTRL["🖥️ Controller Board  (CM5 Carrier)"]
        CB["Raspberry Pi CM5<br>Link-Alpha & Link-Beta docks"]
        JTAG["JTAG Module<br>FT232H USB Blaster"]
        AM_C["Actuation Module<br>Depression bar  (STM32G071K8T3TR)"]
        CB -. "internal BtB J12" .-> JTAG
        CB -. "DF40C-20 BtB" .-> AM_C
    end

    subgraph EXTRSTACK["🔄 Extension Rotor Stack  — up to 30 rotors"]
        subgraph EXTG["Extension Board  +  Actuation Module  ×up to 5"]
            EXT["Extension Board<br>JTAG re-buffer · power bridge"]
            AME["Actuation Module<br>Group-boundary carry  (STM32G071K8T3TR)"]
            EXT -. "DF40HC J9" .-> AME
        end
    end

    REF ~~~ RSTACK ~~~ STATOR
    STATOR ~~~ PWR
    ENCS ~~~ CTRL
    EXTRSTACK ~~~ RSTACK

    PWR -- "Link-Alpha<br>3× TE 2.5mm docks<br>5V_MAIN · 3V3_ENIG" --> CTRL
    CTRL -- "Link-Beta<br>2× Molex EXTreme Guardian HD<br>ENC_DATA · JTAG · I²C" --> STATOR
    JTAG -- "JTAG chain entry" --> STA
    KBD -- "ENC_IN[5:0]" --> STA
    STA -- "ENC_OUT[5:0]" --> LBD
    PLG <-- "ENC_DATA" --> STA
    STA -- "Tri-connector Bus<br>Power · JTAG · ENC_DATA" --> ROT
    ROT -- "ENC_DATA" --> REF
    ROT <---> EXT
    REF -- "ENC_OUT[5:0]<br>TTD_RETURN" --> STA
    STA -- "ENC_IN[5:0]<br>5V_MAIN · 3V3_ENIG" --> REF

• 3V3_ENIG: Provided by the Power Module TPS75733KTTRG3 LDO. Powers all CPLDs, JTAG interface, I2C logic, rotor stack, and Controller digital I/O.
• 5V_MAIN: Provided by the Power Module dual-buck stage. Powers the CM5 main supplies and the 5V system bus.
• GND: Common power and signal ground reference.
• GND_CHASSIS: Safety earth / EMI reference plane.
• PWR_GD: Direct PM -> Controller rail-health signal from the MCP121T supervisor.

Only the Power Module implements the intentional GND ↔ GND_CHASSIS bond.

• Power Module INA219 (0x40): monitors 5V_MAIN
• Stator INA219 (0x45): monitors rotor-stack 3V3_ENIG
• Power Module PCA9534A (0x3F): virtualises PM status lines and SW1 RGB runtime control

• I2C1 (SCL/SDA) originates on the Controller and fans out in parallel:
  • Controller -> Power Module over J3
  • Controller -> Stator over J5
  • Stator -> User Settings Module over J13

Authoritative I2C address table: see Controller/Design_Spec.md §4.1 for the full list of device addresses, locations, and functions across all boards sharing the I2C1 bus (Power Module, Stator, User Settings Module, Cypher-Input). This section documents topology only, to avoid duplicating a table that must otherwise be kept in sync in two places.

• The Controller ↔ Power Module dock uses three TE 10-position 2.5mm connectors.
• The Controller ↔ Stator dock uses two Molex EXTreme Guardian HD hybrid connectors.
• Rotor / Extension / Reflector interconnects use Samtec Edge-Rate connectors.
• All external I/O is grouped on the Controller side of the enclosure.