Enigma-NG Board Overview

Status: Reference Project: Enigma-NG Author: Izzyonstage & GitHub Copilot Version: v1.0.0 Last Updated: 2026-04-20

1. Overview

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.

2. Power Rail Glossary

• 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.

3. Telemetry Sensor Responsibility

• 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

4. I2C Bus Map

• I2C1 (SCL/SDA) originates on the Controller and fans out in parallel:
  • Controller -> Power Module over J3
  • Controller -> Stator over J5
  • Stator -> Settings Board over J_CFG
  • 0x09: LTC3350 supercap charger / monitor (Power Module)
  • 0x0B: Smart Battery / SMBus monitor (Power Module)
  • 0x20: MCP23017 U_EXP1 (Stator ENC monitoring)
  • 0x21: MCP23017 U_EXP2 (Stator virtual keypress / servo control)
  • 0x22: MCP23017 U_EXP4 (Stator CPLD config output driver)
  • 0x23: MCP23017 U_EXP_SW_IN (Settings Board switch input)
  • 0x24: MCP23017 U_LED_B1 (Settings Board Bank 1 LED controller)
  • 0x25: MCP23017 U_LED_B2 (Settings Board Bank 2 LED controller)
  • 0x28: STUSB4500 USB PD controller (Power Module)
  • 0x3F: PCA9534APWR PM-local GPIO expander (Power Module)
  • 0x40: INA219 (Power Module)
  • 0x45: INA219 (Stator)
  • 0x60: PCA9685 (Stator servo PWM)

5. System Architecture & Status

Board Name	Role	Stackup	Status
Controller Board	Fixed motherboard; CM5 host; external RJ45, Ethernet ESD/magnetics, PoE front-end, HDMI, USB 3.0, and service docks for PM + Stator	6-Layer / 2oz	In Review
Encoder Module	Dual-use Keyboard / Plugboard / Lampboard logic using 2x Intel MAX II EPM240T100I5N CPLD	4-Layer / 2oz	In Review
Extension Board	Re-buffers TCK/TMS between 5-rotor groups; forwards/reinjects clean power and bridges TTD_RETURN between stacks	4-Layer / 2oz	Design Locked
JTAG Daughterboard	Internal FT232H-based hardware programmer	4-Layer / 2oz	Design Locked
Power Module	Removable power-conditioning / UPS cartridge with supercaps, eFuse, OR-ing, USB-C input, battery input, and PM-local status expander	6-Layer / 2oz	In Review
Reflector Board	Mandatory terminating turnaround board for the rotor stack return path	4-Layer / 2oz	Design Locked
Rotor Module	Smart encryption units (30x) with MAX II EPM570T100I5N CPLDs	4-Layer / 2oz	Architecture Set
Settings Board	Panel-mount switch and RGB LED configuration interface on the shared Stator I2C-1 bus	4-Layer / 2oz	In Review
Stator Board	Removable vertical daughterboard; rotor-stack backplane and CPLD routing hub	4-Layer / 2oz	In Review

6. Notes

• 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.