Railway infrastructure

Connected LED signal marker board for railway applications

A battery-powered, IoT-connected LED marker board for trackside work areas — redundant illumination, onboard fault and battery alerting, GNSS tracking and OTA-updatable firmware.

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Overview

What was delivered

XceedMinds delivered a turn-key engagement — spanning hardware, firmware and prototyping — for a battery-powered, IoT-connected LED signal marker board used to mark trackside work areas.

The board combines redundant LED lighting, onboard fault detection with local and remote alerting, battery health monitoring and GNSS-based asset tracking into a single ruggedised, battery-operated unit built around an STM32L431CBT6 MCU.

  • STM32L431
  • LTE-M / NB-IoT
  • eSIM multi-operator
  • GNSS
  • OTA updates
  • Battery health

The challenge

What made it difficult

The constraints that shaped every decision downstream.

01

Fail-safe, redundant illumination

LEDs had to be arranged across multiple independent strings so that a single string or driver fault could not take the marker dark, with the board itself detecting that fault rather than relying on someone noticing it in the field.
02

Remote visibility into an unattended asset

Fault conditions and battery health needed to reach both a local indicator and a remote system in real time, from a board with no wired connection and no one nearby to check on it.
03

Carrier-independent connectivity on a tight power budget

LTE-M/NB-IoT connectivity, multi-operator eSIM provisioning and GNSS positioning all had to run continuously enough to be useful, without draining a battery-powered board meant to sit trackside for extended periods.
04

Turn-key hardware, firmware and prototyping ownership

One team had to carry schematic design, PCB layout, firmware and prototyping — component procurement through PCB fabrication and assembly — as a single accountable delivery.

The solution

How it was built

  1. Core design

    An STM32L431CBT6 MCU coordinates LED string driving and fault detection, battery health monitoring, GNSS positioning and cellular communication from a single low-power platform.

  2. Firmware architecture

    Peripheral and clock configuration were generated with STM32CubeMX and built out in STM32CubeIDE on the STM32Cube HAL/LL driver layers, with production units flashed and verified via STM32CubeProgrammer. Firmware supports over-the-air updates, so units already deployed trackside can be updated remotely without physical access.

  3. Redundant illumination

    Railway-grade LEDs are arranged across multiple independent LED strings, so a single string failure degrades brightness rather than extinguishing the marker.

  4. Fault detection and alerting

    The board continuously monitors each LED string and raises both a local indication and a remote alert the moment a fault is detected, rather than waiting for the next physical inspection.

  5. Battery and health monitoring

    A 24V rechargeable battery powers the board, with onboard monitoring tracking battery health and reporting it alongside LED fault status.

  6. Cellular connectivity and GNSS

    A GM02S-class LTE-M/NB-IoT module, paired with an embedded eSIM provisioned for multi-operator use, keeps the board connected across regions and carriers without a physical SIM swap. An onboard GNSS receiver reports the board’s location — useful for a marker that gets relocated as work zones move along the track.

Specifications

Technical detail

The numbers the design had to hit.

LEDs
Railway-grade LEDs, arranged in multiple redundant strings
Power
24V rechargeable battery
Monitoring
Onboard fault detection (local + remote alerting), battery health monitoring
Positioning
GNSS-based asset tracking
Cellular connectivity
GM02S module, LTE-M / NB-IoT
SIM provisioning
Embedded eSIM, multi-operator
Firmware updates
Over-the-air (OTA)
MCU
STM32L431CBT6
Firmware toolchain
STM32CubeMX, STM32CubeIDE, STM32Cube HAL/LL drivers, STM32CubeProgrammer

Scope

Turn-key delivery

Everything carried under one engagement, with no handoff gaps between stages or vendors.

Hardware

Schematic design and PCB layout engineered around the LED driver strings, battery management, cellular module and GNSS receiver.

Firmware

Embedded firmware for LED string fault detection, battery health monitoring, GNSS positioning, cellular communication and OTA update handling.

Prototyping

Component procurement and PCB fabrication & assembly.

Highlights

What stands out

Redundant, self-monitoring illumination

Multiple independent LED strings with onboard fault detection mean a single failure degrades output instead of going dark unnoticed.

Carrier-independent cellular IoT

LTE-M/NB-IoT connectivity via a GM02S module and a multi-operator embedded eSIM keep the board online without being locked to a single carrier or region.

GNSS asset tracking on a battery budget

Location tracking runs alongside connectivity and monitoring without compromising the battery life a trackside, unattended board depends on.

Field-updatable via OTA firmware

Firmware can be updated remotely after deployment, so units already in the field do not require physical access to stay current.

Outcome

Where it ended up

A production-ready connected LED signal marker board — spanning hardware, firmware and prototyping — unifying redundant, self-monitoring illumination, cellular IoT connectivity, GNSS asset tracking and OTA-updatable firmware into a single battery-powered unit ready for trackside deployment.

More work

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Sensor fusion & haptic platform

Motion and load data fused on-device so feedback happens in milliseconds, not after a cloud round trip — on a wearable-scale power budget.

Building something similar?

Send a specification, a block diagram, or a description of the problem. We will come back with an honest view of scope, risk and the fastest route to a working prototype.

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