PCB design · Embedded Linux · In progress

AltiLink: Portable PoE Switch & Field Analyzer

Battery-powered field unit that powers, monitors, and bridges Ethernet devices where no wall power exists.

Context: EECS 473: Advanced Embedded Systems · University of Michigan
Role: Team of 5 · 54 V PCB design and gigabit local networking
When: Fall 2026

Altium
TPS23861
Raspberry Pi 5
Linux networking
PoE
OLED

Constraint

Construction engineers installing IP cameras, access points, and intercoms often need PoE power, power measurement, and a working link before building power or cabling exists.

Decision

Split the job: a four-layer PoE injector PCB (54 V / 3.3 V rails; built around the TPS23861) delivers power, while a Raspberry Pi 5 routes network traffic at Layer 3 and runs telemetry and the UI.

Evidence

In progress. Targets: ~200 Wh battery for about four hours of single-device testing, live voltage/current/power on OLED, PoE and link LEDs.

01 // Problem & constraints

Existing products either supply portable PoE or run network diagnostics, rarely both in one box. AltiLink must work off-grid, measure the power a device draws, and confirm a data-capable Ethernet link.

02 // Architecture

▪Four-layer PCB with 54 V and 3.3 V power lines centered on the TPS23861 PoE controller.
▪Passive transformer paths on the PCB; switching and routing handled by the Pi's Linux networking stack.
▪Pi configured as a Layer 3 router, so devices preconfigured on different subnets remain reachable.
▪OLED shows voltage, current, power, and battery percentage; separate LEDs show PoE power and link status.

03 // Two operating modes

▪No laptop: AltiLink shows basic network and power diagnostics itself.
▪With a laptop: acts as a PoE adapter, powering the device while passing traffic for configuration and video.

04 // Scope

▪Guaranteed: one powered PoE device port.
▪Expected: a second PoE port and additional network information.
▪Stretch: four powered ports, telemetry history, richer device-to-device streaming, adjustable DC output.

Measured results will be added once the hardware is built and tested.