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8. Modules & Extensions

SMHUB is designed to be modular. The main board provides essential radios, networking, and I/O, while additional hardware modules extend functionality for power resilience, connectivity, and advanced integrations.

8.1 USB Passthrough

  • Purpose: Enables SMHUB to act either as a USB host (powering connected peripherals) or as a USB device (connected to a PC or another host).

  • Logic:

    • Automatically decides whether to supply or draw power.

    • Prevents reverse powering through integrated FET switching.

  • Use Cases:

    • Attach Z-Wave or extra Zigbee dongles, printers, audio devices, storage etc.

    • Connect SMHUB to a PC for development/debugging.

    • Power downstream devices safely.

8.2 SD Card

  • Slot: Standard microSD slot on the main board.

  • Purpose: Expand storage for logs, app data, or backups.

  • Integration:

    • Mounted automatically by the Linux OS.

    • Users can format, mount/unmount, and monitor usage from the UI.
    • Support up to 2Tb volume.

8.3 PoE Module

  • Standard: IEEE 802.3af-compliant.

  • Input: Power delivered via Ethernet cable from a PoE-enabled switch or injector.

  • Output: Stable 5V regulated supply to the hub.

  • Protection: Surge and ESD protection integrated.

  • Monitoring: “PoE Power Check” exposed in the system for telemetry.

  • Use Case: Ideal for enterprise deployments where powering over Ethernet is standard.

8.4 UPS Module

  • Battery: Supports 18650 Li-ion cells (user-installed).

  • Charger: advanced circuit with overcharge/undervoltage protection.

  • Conversion: Step-up/step-down converters to maintain 5V, 3.3V, 1.8V rails.

  • Telemetry:

    • Monitors voltage/current

    • Provides battery health and charge state in the UI.

  • Inputs: Can also accept DC power or solar panels, making SMHUB deployable off-grid.

  • Use Case: Ensures uninterrupted operation during outages.

8.5 4G/LTE Module

  • Connectivity: LTE Cat 1 with fallback modes.

  • Interfaces:

    • Main UART.

    • USB.

    • Debug UART.

  • SIM Slot: NanoSIM with detection circuitry.

  • Antennas: Dedicated connectors for LTE and GNSS.

  • UI Integration:

    • Settings → Radios → 4G/LTE.

    • SIM/APN configuration, LTE signal telemetry.

  • Status: Hardware available, software support in development.

8.6 DIY Pinouts & Interfaces

For advanced users and developers, SMHUB exposes additional hardware interfaces:

  • GPIO pins for general use.

  • UART, SPI, and I²C buses.

  • Custom module connectors for prototyping or specialized hardware.

  • Use Case: Attach sensors, control boards, or experimental expansions not covered by official modules.

8.7 Integrated Peripherals

While not separate modules, the following are considered part of SMHUB’s extension capabilities:

  • IR Transmitter & Receiver

    • Control TVs, AC units, and IR-based devices.

    • Capture IR codes for learning mode.

  • Audio Output (3.5 mm)

    • System alerts and future media/streaming support.

  • Buzzer

    • Local audible notifications.

  • LED Systems

    • 12 WS2812B RGB LEDs (Ambilight) – running by default, user configurable.

    • 4 Service LEDs – network, power, radio status.

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