IoT GAT: Global Asset Tracking System

The Problem

Tracking assets in the field — trucks, containers, agricultural equipment, construction machinery — requires a device that runs for years without maintenance. Commercial trackers either drain fast or cost too much per unit to deploy at scale. The client needed a custom GPS/GSM module that could survive a 2-year field deployment on a single battery charge.

What We Built

A compact GPS tracking module based on the STM32 microcontroller (ARM Cortex-M) and the SIM808 combined GPS+GSM module. The device records location via GNSS and transmits it to a cloud backend over GSM, GPRS, or USSD — whichever channel is available on the network. An ADXL345 accelerometer detects motion and wakes the device from deep sleep only when the asset moves, avoiding wasted transmissions when equipment is stationary.

The cloud backend ingests location events, stores the track history, and exposes it to a mobile app where operators monitor their assets in real time.

Power Architecture

Two operating modes:

Continuous mode — GPS fix every 30 seconds, immediate GSM transmission. Battery life: ~10 hours. For high-value assets during active transit where real-time position is critical.

Sleep mode — MCU in deep sleep, ADXL345 on interrupt watch. Device wakes on movement, acquires GPS fix, transmits, returns to sleep. Battery life: 2.2 years on a single 3.7V Li-Ion cell.

The 2.2-year figure was achieved through peripheral power gating, RTC-based sleep scheduling, and transmission batching: several location records are buffered locally and sent in one burst rather than one request per fix.

Technical Stack

• MCU: STM32L4 (ARM Cortex-M4, ultra-low-power)
• GPS + GSM: SIM808 — combined GNSS receiver and quad-band GSM/GPRS modem
• Motion: ADXL345 three-axis accelerometer on interrupt line
• Transmission: GPRS (primary), USSD (fallback on networks without data)
• Cloud backend: REST API, time-series location storage, geofence alerting
• Mobile: iOS and Android app with live map, track history, and alert settings

Applications

Fleet management — logistics companies tracking trucks and vans across routes. Geofence alerts when a vehicle enters or exits a zone. Idle detection to flag unauthorized use.

Cold chain — containers and refrigerated units where remote monitoring eliminates manual check-ins at each stop.

Agricultural equipment — tractors and harvesters spread across large farms. The 2.2-year battery means no seasonal charging; hardware is installed and forgotten. For full-stack agritech platforms combining GPS tracking with crop monitoring and irrigation control, see our agritech software development practice.

Construction and rental equipment — high-theft-risk machinery tracked across job sites. Instant alert on movement outside working hours.

Result

A field-deployable tracking device with 2.2-year battery life, cost-effective enough to deploy across large fleets, with cloud infrastructure and a mobile app ready for production. The device transmits reliably via USSD even on networks that throttle or block GPRS data — a requirement specific to certain emerging-market deployments.

Built a similar tracking requirement? CimpleO’s IoT engineering team handles the full stack — hardware selection or custom device design, firmware, cloud backend, and mobile app. Tell us about your project.