Physical Layout & I/O

Pinouts, ports, connectors, and indicators on the ALPON — a compact industrial edge AI computer built on Raspberry Pi CM5 with a 25 TOPS DEEPX NPU. This reference covers every externally accessible interface, its electrical characteristics, and the GPIO mapping required to drive it from software.

Device layout overview

The ALPON enclosure is a fanless aluminum case measuring 100 × 100 × 45 mm, weighing approximately 457 g, rated IP40, and designed for -20°C to +60°C ambient operation. All I/O is distributed across the front and rear faces; the top face doubles as a passive cooling surface.

Front face (1–7)

Rear face (8–12)

Enclosure (13–15)

Mechanical specifications

Download the full 2D dimensional drawings for CAD integration: ALPON X5 AI Dimensions (PDF).

Power input

The ALPON accepts power from three independent interfaces. There is no hardcoded priority between inputs — the device always draws from the source with the highest voltage. All three inputs pass through ideal diodes on the main board, so simultaneous connection is tolerated but not recommended.

1. USB Type-C PD Input

Sink-only USB-PD port — does not provide USB data or power output during normal operation. Works as a USB data input only in Burn (image flashing) mode.

2. Screw Terminal Block (12–32V DC)

The recommended input for industrial edge computing deployments. Terminal block includes hardware-level reverse-polarity protection; the device will not be damaged by swapped + / − wiring, but it also will not power on.

3. Power over Ethernet (PoE+)

PoE+ is available only on PoE-variant SKUs and cannot be added after manufacture. When present, PoE+ is wired to ETHERNET 0. ETHERNET 1 does not accept PoE.

Restricted Mode

If any power source drops below 12 V (for example, a 5 V supply on USB-C), the device automatically enters Restricted Mode — a protective state that keeps the system running on minimal power without risking brownout damage to the NPU or SSD.

Power consumption

Measured subsystem power draw at idle, 50% load, and full load. A dash (–) indicates the subsystem draws negligible standalone power at that level.

Values are approximate. Actual consumption varies with workload, connected peripherals, and ambient temperature.

Ethernet ports

Two Gigabit (1 Gbps) RJ45 Ethernet ports with different electrical topologies. Use both simultaneously for WAN + LAN routing, dual-NIC redundancy, or network isolation between trusted and field segments.

USB ports

Two USB 3.0 ports rated at 5 Gbps each, with a combined power budget of 1.8 A (5V) across both.

Display (HDMI 2.0)

Single HDMI 2.0 port driven directly by the CM5. Supports up to 4K @ 60 Hz with HDR and pass-through audio. For supported refresh-rate and color-depth combinations, refer to the Raspberry Pi CM5 datasheet.

Camera port (MIPI-CSI)

The camera interface exposes the CM5's MIPI CSI-2 lane through a Mini HDMI connector on the front face. This is the primary input path for edge AI vision workloads running on the DEEPX NPU.

GPIO Add-on port (RJ45)

The GPIO port exposes six configurable CM5 pins over an RJ45 connector, providing I²C, UART, and SPI to ALPON Edge Add-on modules. Signals are 3.3 V logic with built-in level conversion, ESD protection, and 1 kΩ hardware pull-ups.

Pin assignment

Electrical characteristics

Power-switch control

The port's 5 V supply and all signal I/O are gated by an on-board power switch. The switch must be explicitly enabled in software before the port becomes active — signals will not propagate while GPIO 21 is LOW.

Minimum enable sequence:

# Enable GPIO Add-on port power rail
pinctrl set 21 op dh      # drive GPIO 21 HIGH
pinctrl get 20            # read fault line — should return 1 (HIGH)

LED indicators

Four LEDs on the front face report system state. All LEDs are driven via the TCA6408 I²C I/O expander at address 0x20 on the I²C1 bus (SDA: GPIO 2, SCL: GPIO 3).

Push buttons

Two user-programmable push buttons — PB1 on the front face and PB2 on the rear face. Both lines are pulled HIGH by default and read LOW while pressed.

Watchdog & Boot/Burn switches

Two DIP switches are accessible under a silicone cap on the rear face. Both ship OFF by default and should remain OFF during normal operation. Use a pointed tool to gently lift the cap from its notch.

SW1 — Hardware watchdog

The hardware watchdog monitors system liveness independently of the OS. When enabled (SW1 OFF), the CM5 must toggle GPIO 16 at least once every 5 minutes. If no trigger arrives, the watchdog cuts all power to the device, waits 3 seconds, then re-applies power to force a cold reboot.

• Trigger pin: GPIO 16
• Timeout: 5 minutes
• Recommended period: a 2-second HIGH pulse every 60 seconds
• Status read pin: GPIO 8 — HIGH when SW1 = OFF (watchdog enabled), LOW when SW1 = ON (watchdog disabled)
• Disable method: physical SW1 only — no software command exists

SW2 — Boot / Burn mode

SW2 selects between normal operation (Boot) and CM5 image flashing over USB-C (Burn). In Burn mode, the USB-C port exposes the CM5's flashing interface to a host PC running rpiboot.

Antenna connectors

Four SMA connectors on the rear face carry the wireless interfaces. Labels on the enclosure identify each port.

For radiation patterns, gain charts, and supported LTE bands, see Connectivity & Antenna Specifications.

Internal bus topology

Understanding how I/O maps back to the CM5 helps diagnose throughput and power-sharing issues. The diagram below summarizes the primary data paths.

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