Electronics Electrical Design - thepinkmile/Enigma-NG GitHub Wiki
Electrical Design Requirements
Status: Reference Version: v1.0.0 Last Updated: 2026-04-19
1. Component Rules (The "Museum-Grade" Standard)
- Dielectric: X7R for all ceramic capacitors (Strictly no Y5V or Z5U).
- Derating: 2.5x Voltage rating for all power capacitors (e.g., 50V caps on 15V rails).
- Tolerance: 1% precision resistors for eFuse ladders and INA219 current-sense shunts.
- Vias: Teardrops on all signal/power vias; 0.3mm drill standard; VIPPO (Via-In-Pad) for high-density CM5/eFuse pads to prevent solder wicking.
2. I2C Bus Address Table
| I2C Address | Device | Module | Function |
|---|---|---|---|
| 0x09 | LTC3350 | Power Module | Supercap charger / health monitor |
| 0x0B | Smart Battery | Power Module | Smart battery / SMBus monitor |
| 0x28 | STUSB4500 | Power Module | USB-C PD Controller |
| 0x3F | PCA9534A | Power Module | PM-local GPIO expander (POE_STAT, SYS_FAULT, BATT_PRES_N, USB_STAT, SW1 RGB control) |
| 0x40 | INA219 | Power Module | 5V_MAIN current/power monitoring (10mΩ Kelvin-sense shunt R23) |
| 0x20 | MCP23017 | Stator | ENC monitor expander (U_EXP1) |
| 0x21 | MCP23017 | Stator | Virtual keypress / SOURCE_SEL / SYS_RESET_N / servo expander (U_EXP2) |
| 0x22 | MCP23017 | Stator | CPLD configuration output expander (U_EXP4) |
| 0x23 | MCP23017 | Settings Board | Switch input expander (U_EXP_SW_IN) |
| 0x24 | MCP23017 | Settings Board | Bank 1 LED controller (U_LED_B1) |
| 0x25 | MCP23017 | Settings Board | Bank 2 LED controller (U_LED_B2) |
| 0x45 | INA219 | Stator | Rotor stack power telemetry (CSS2H-2512R-R010ELF 10mΩ shunt R1) |
| 0x60 | PCA9685 | Stator | Servo PWM driver (U_EXP3) |
Note: This document captures global electrical design rules. Board-specific design rules are in each board's Design_Spec.md. Full design decision history: See
design/Design_Log.md.