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Precise Low-Current Measurement Techniques for IoT Devices: A Case Study on MoleNet

Julian Block, Andreas Könsgen, Jens Dede, Anna Förster

TL;DR

This work addresses the challenge of obtaining precise low-current measurements for battery-powered IoT devices. It surveys and compares multiple source measurement units (SMUs), spanning add‑on and standalone types, using the MoleNet sensor board as a demonstration platform. Key findings show that high‑sampling‑rate instruments like the JouleScope capture rapid current spikes that slower meters miss, with the tinyCurrent offering a cost-effective option albeit with automation limitations. The results provide practical guidance for selecting SMUs for automated, high‑fidelity energy profiling in IoT deployments and outline directions for optimizing sleep and transmit‑state energy in LoRa-enabled devices.

Abstract

Power consumption is a crucial aspect of IoT devices which often have to run on a battery for an extended period of time. Therefore, supply current measurements are crucial before deploying a device in the field. Multimeters and oscilloscopes are not well suited when it comes to measuring very small currents which occur e.g. when an IoT device is in sleep mode. In this report, we compare dedicated source measurement units (SMUs) which allow to measure very small currents with high precision. As an application example, we demonstrate current measurements on our MoleNet IoT sensor board.

Precise Low-Current Measurement Techniques for IoT Devices: A Case Study on MoleNet

TL;DR

This work addresses the challenge of obtaining precise low-current measurements for battery-powered IoT devices. It surveys and compares multiple source measurement units (SMUs), spanning add‑on and standalone types, using the MoleNet sensor board as a demonstration platform. Key findings show that high‑sampling‑rate instruments like the JouleScope capture rapid current spikes that slower meters miss, with the tinyCurrent offering a cost-effective option albeit with automation limitations. The results provide practical guidance for selecting SMUs for automated, high‑fidelity energy profiling in IoT deployments and outline directions for optimizing sleep and transmit‑state energy in LoRa-enabled devices.

Abstract

Power consumption is a crucial aspect of IoT devices which often have to run on a battery for an extended period of time. Therefore, supply current measurements are crucial before deploying a device in the field. Multimeters and oscilloscopes are not well suited when it comes to measuring very small currents which occur e.g. when an IoT device is in sleep mode. In this report, we compare dedicated source measurement units (SMUs) which allow to measure very small currents with high precision. As an application example, we demonstrate current measurements on our MoleNet IoT sensor board.
Paper Structure (8 sections, 5 figures, 1 table)

This paper contains 8 sections, 5 figures, 1 table.

Table of Contents

  1. Introduction
  2. Tested Devices
  3. Add-on devices
  4. Stand-alone devices
  5. Example Measurements
  6. Test suite
  7. Individual test with LoRa
  8. Conclusion and Outlook

Figures (5)

  • Figure 1: Current intake of MoleNet board vs. time, measured with R&S for different microcontroller clock frequencies
  • Figure 2: Current intake of MoleNet board vs. time, measured with JouleScope for different microcontroller clock frequencies
  • Figure 3: Current intake of MoleNet board vs. time for running the LoRa interface, measured with R&S
  • Figure 4: Current intake of MoleNet board vs. time for running the LoRa interface, measured with JouleScope
  • Figure 5: Current intake of MoleNet board vs. time for running the LoRa interface, measured with tinyCurrent