Energy Harvesting LoRaWAN Sensor Node

Problem

Environmental sensors in the field are usually limited by their batteries, not their electronics. The goal of this project was a LoRaWAN sensor node that runs from harvested energy, which means every part of the board has to respect a tight power budget, and the power draw has to be measurable rather than assumed.

Approach

I designed and fabricated a custom 2-layer PCB around a low-power microcontroller and a long-range radio, with an energy harvesting power path and a switched sensor rail. Measurement was part of the design from the start: the board carries inline PPK2 measurement headers so the current draw can be profiled across the full LoRaWAN transmission cycle.

Architecture

• MCU: an ATMEGA4809 microcontroller.
• Radio: an XL1276 LoRa transceiver handles the LoRaWAN link.
• Power: an AEM10330 PMIC manages the energy harvesting path, and a MIC94069 load switch gates the switched rail.
• Sensors: a BME680 environmental sensor and a CO sensor.

Why measure

In a LoRaWAN node the radio transmission is typically the largest current draw, and the long idle stretch between transmissions is where a board slowly drains its storage. Seeing both takes current measurement across the whole cycle rather than a single reading, which is why the measurement headers are designed into the board instead of added later.

Process

The work covered schematic capture and layout in EasyEDA, IPC-2221-compliant trace routing, and fabrication of the 2-layer board. The inline PPK2 headers turn current profiling into a routine measurement instead of a rework job.

My role

I designed the schematic and the layout and had the board fabricated. There is no public repository for this project.