Making Ambient IoT Easy with the xG22E Energy Harvesting Explorer Kit

Over the past year, Ambient IoT has rapidly emerged as one of the most dynamic and fast-growing areas within the IoT space. As more device manufacturers seek energy-efficient, battery-free solutions for long-lasting, uninterrupted performance and enhanced reliability, Ambient SoCs have become an optimal choice.

Last April, Silicon Labs introduced the xG22E, our most energy-efficient SoC to date. This series enhances our existing xG22 family (BG22E SoC, MG22E SoC, and FG22E SoC) by integrating features that support energy harvesting technology.

Silicon Labs has collaborated with e-peas, a top provider of PMIC solutions, to develop an Explorer Kit Shield. This kit features three shields that securely integrate with the Explorer Kit Board, designed to eliminate power leakages and enable external measurements. It is ideal for various applications, including asset tracking, smart home switches, industrial monitoring, and electronic shelf labels. The kit allows evaluation of multiple energy harvesting solutions using sources such as photovoltaic cells and thermoelectric generators (TEG) in different scenarios. The three included shields are:

BRD8201A – Dual Harvester Shield

This shield enables experimentation with alternative battery chemistries and supercapacitors, allowing energy harvesting from two sources simultaneously.

BRD8202A – Kinetic Button Shield with BRD8206A – Kinetic Button

Designed for kinetic and pulse energy harvesting applications, this shield demonstrates how a kinetic switch can power a wireless SoC. It utilizes the e-peas AEM00300.

BRD8203A – Battery Shield

Equipped with e-peas’ latest PMIC, the AEM13920, this shield allows developers to experiment with dual energy harvesting sources, debug standalone operation scenarios, and evaluate battery longevity.

Now, let’s dive into the kit’s design, key components, and setup process for each shield.

Design and Components

At Silicon Labs, the vision is to drive the future of sustainable IoT product design. Our goal is to enable IoT end devices with exceptionally long lifespans while minimizing their environmental impact. This vision has been a key motivation behind the development of the Energy Harvesting MG22E Explorer Kit.

Creating a battery-free, energy-harvesting device requires a fresh approach and careful selection of components. Every element—from the energy source and storage to power management, firmware algorithms, and IoT protocols—plays a crucial role in optimizing both performance and cost. You can find more details about these key components here.

Energy Harvesting Explorer Shield Kit – Key Methodology

The Energy Harvesting Explorer Shield Kit provides users with a structured approach to evaluating each essential component, following this general methodology:

1. Define the Application Power Budget

Analyze the application’s peak and average current consumption, considering factors like radio events and sleep intervals to determine overall energy requirements.

2. Evaluate Available Energy Sources

Ambient energy can be harvested from various sources, including light, vibration, heat exchange, electromagnetism, and kinetic pulses. The most suitable source depends on the application’s voltage, current, and impedance needs. The Explorer Shield Kit supports both AC and DC power sources, featuring built-in rectifiers and regulators for efficient conversion.

3. Conduct Energy Measurements & Select Power Management Components

The MG22E Explorer Shields include multiple PCB test points along the energy pathways, enabling precise power consumption analysis using test-bench equipment. Additionally, Silicon Labs Simplicity Studio offers advanced tools like Power Analyzer, allowing continuous energy optimization.

4. Determine Storage Type & Capacity

Once the energy budget and key consumption parameters are established, the appropriate storage component can be selected. Unlike traditional batteries, capacitor-based storage can be fine-tuned to match specific energy requirements. The MG22E Explorer Kit Shields support various capacitor technologies via screw-in terminals, offering flexibility in form factors and costs.

5. Choose the Right IoT Protocol & Implement Energy Algorithms

At the heart of Ambient IoT, the IoT SoC plays a crucial role. The MG22E is Silicon Labs’ most power-efficient, platform-optimized SoC, supporting multiple 2.4GHz protocols such as Bluetooth LE, Zigbee Green Power, and proprietary 2.4GHz solutions. Leveraging Silicon Labs RAIL protocol, developers can dynamically adjust payload, Tx power, PHY, and sleep intervals based on real-time energy measurements, optimizing efficiency for beaconing devices.

Introduction to the MG22E Shields with e-peas

At e-peas, we are committed to driving the future of battery-free IoT by enabling devices to harness energy from ambient sources. As part of this mission, we have partnered with Silicon Labs to make energy harvesting technology more accessible to developers at all levels—from students to experienced engineers—helping them create sustainable, self-powered IoT solutions with ease.

That’s why the MG22E Explorer Kit features MikroBus and qwiic connectors, enabling seamless integration of sensors for advanced applications.

e-peas is soley dedicated to creating circuitry to address ambient energy sources and we have worked closely with Silicon Labs engineers to create these shields and compatible drivers for Simplicity Studio.

source: https://www.powerelectronicsnews.com/energy-harvesting-for-autonomous-systems/

The concept of the shield kit is to leverage existing Silicon Lab hardware. The MG22E Explorer Kit is a developer board with breakout pins and programming ports. Silicon Labs designed a kit of adaptable shields that piggy-back on the Explorer Kit and add a host of new power capability. User Guide 591 offers a complete user manual for the hardware installation. A sample PV cell and capacitor are included.

Shield #1 – BRD8203 – Battery Backpack

BRD8203 Battery Shield serves as a baseline to easily power the Explorer Kit with a battery, capacitor, or alternate PMIC circuitry. This allows users to take measurements to compare battery and battery-less performance quickly.

The shield has multiple test-points and a switch to transition between sources and is used to explore different battery and capacitor chemistries. This shield also allows double-stacking of additional shields. Users can experiment between different protocols and application settings to establish a baseline before proceeding to further energy harvesting hardware design. This shield does not have a PMIC circuit. Examples can be configured to use the internal MG22E power management.

Shield #2 – BRD8202 – Kinetic Button – AEM00300

Shield BRD8202 is a dedicated shield for battery-less switches and buttons. This shield includes a built-in harvester kinetic switch that rectifies energy on the press and depress of the button. No additional external storage element is required in this design. The button provides enough energy to very briefly power on-board banks and communicate.

The e-peas AEM00300 is at the heart of this shield and has been configured to be optimal for this energy source. Software examples have been provided for beaconing Zigbee Green Power and Bluetooth LE RAIL packets.

Shield #3 – BRD8201 – Dual Harvester – AEM13920

Shield BRD8201 is the master shield for energy harvesting designers. This shield (along with the AC DC adapter bridges) provides users with all the necessary ingredients to build, measure, compare, and improve ambient IoT sources. This shield caters to two energy sources simultaneously (AC or DC). This allows users to create multi-sourced devices or compare and contrast between two sources very easily. The kit has multiple test-points and enables further stacking or additional sensors.

e-peas’ newest AEM13920 is the heart of this shield which is ou most advanced PMIC. The driver is hosted on Silicon Labs repos and configurable in Simplicity Studio. This powerful PMIC is meant to allow designers to tailor their design (using i2c driver interface) or assist in narrowing down on the correct PMIC needed for the application. This shield also accommodates controllable fast charging via USB connection and jumper terminal.

Input AC-DC Adapters – BRD8204 BRD8205

Silicon Labs and e-peas have ensured that every aspect of energy harvesting design can be addressed easily with this kit by using what is included, modifying sample apps, or connecting additional external circuitry. To address both types of energy sources (AC and DC), adapter bricks of regulator and rectifiers have been included and can easily be screwed in to shield terminals.

The AC input adapter is a MOSFET based rectifier smoothed by a capacitor and a protection circuit. This is meant for AC sources like vibration or electromagnetic induction. The DC input adapter also includes over-voltage protection which was omitted from original shield designs as optional. The adapter provides a placeholder for extra capacitance.

Setting Up The Energy Harvesting Explorer Kit

For many new developer kits, the out-of-box experience is crucial to a project’s success. As the IoT experts, Silicon Labs was able to provide a selection of sample applications that are compatible with the MG22E Explorer board. These examples are available open-source at github.com. They can be cloned, compiled and flashed to the Silicon Labs MG22E like any other example.

The default installed example is Bluetooth RAIL Sensor. Upon screwing in the PV cell and capacitor provided, the device will immediately begin beaconing on its own!

Each example has a thorough README that highlights the firmware’s behaviour and expected performance. These apps are intended to be generic and easily modified for asset tracking or smart building sensors, etc. They are meant to highlight the differences between energy source and IoT protocol. Examples cover sensor use cases and switches. The beacons are detectable on Silicon Labs’ free EFR Connect mobile app. Additionally, a dedicated MG24 Explorer Kit (not included) sample app can be installed and act as a reader or coordinator for Bluetooth LE, RAIL, and Zigbee protocols. e-peas AEM drivers are also hosted in the GitHub and easily modified in Simplicity Studio.

Now it is up to you to start measuring, coding and adding sensors! Welcome to the wonderful world of Ambient IoT.

Reach out to us if you have any questions: www.e-peas.com/contact