Simplifying Ambient IoT with xG22E Energy Harvesting Explorer Kit
Over the past year, Ambient IoT has been one of the fastest growing sectors within the IoT. With an increasing number of device makers and manufacturers looking for energy-optimized, battery-less solutions for long-lasting devices with uninterrupted performance and increased reliability, Ambient SoCs are the ideal choice.
Last April, Silicon Labs introduced our most energy-friendly SoC to date - the xG22E. This series optimized our xG22 line of SoCs (BG22E SoC, MG22E SoC, and FG22E SoC) to include features that will support energy harvesting.
We are now expanding our portfolio as the industry-leading supplier of energy harvesting and power-optimized solutions for IoT. Silicon Labs has partnered with e-peas, an industry leading provider of PMIC, to develop an Explorer Kit Shield. This kit includes three shields that fit securely into the Explorer Kit Board, which has been designed to prevent any power leakages and facilitate any external measurements, and is ideal for applications like asset trackers, home switches, machinery monitoring, and electronic shelf labels. The kit enables evaluation of multiple solutions for energy harvesting, by utilizing sources like photovoltaic cells, thermoelectric generators (TEG) in different applications. It contains the following three shields:
- BRD8201A - Dual Harvester Shield
- This shield allows for experimentation with alternative battery chemistries and supercapacitors. It can be used to harvest energy from up to two sources at the same time.
- BRD8202A - Kinetic Button Shield equipped with BRD8206A - Kinetic button
- This shield allows the demonstration of a specific application using a kinetic switch to power the wireless SoC. It’s dedicated for kinetic/pulse harvest applications and uses the e-peas AEM00300.
- BRD8203A - Battery Shield
- This shield uses e-peas' latest and most advanced PMIC, the AEM13920, and allows developers to experiment with dual harvest sources simultaneously, debug standalone operation scenarios, and evaluate battery lifetime.
Let's explore the kit's design, components, and setup process for each shield.
Design and Components
Silicon Labs’ vision is to usher in the era of sustainable IoT product design. The objective is to offer IoT end devices extremely long lifetimes and improved ecological footprint. This is the primary motivation behind the new Energy Harvesting MG22E Explorer Kit . Designing a battery-less energy-harvesting device requires a new methodology and careful analysis of components. Each aspect from energy source, energy storage, power management, firmware algorithms and IoT protocol have important impacts on optimizing the design and cost. More on these key components can be found at here.
The Energy Harvesting Explorer Shield Kit allows users to run through the proper assessment of each key component following this general methodology.
- Understand the application power budget:
- Determine the application’s peak and average current consumption based on radio events and sleep intervals.
- Assess available energy sources:
- Energy can be harnessed from a multitude of ambient sources (such as light, vibration, heat exchange, electromagnetism and kinetic pulse). Each application may be best suited for a particular source based on its voltage, current and impedance needs. The Explorer Shield Kit is suited for both AC and DC power sources with rectifiers and regulators.
- Energy measurements and power management selection:
- The MG22E Explorer Shields offer multiple PCB test-points throughout the energy paths to take measurements to determine energy consumption with test-bench equipment. Furthermore, Silicon Labs Simplicity Studio offers extended tools like Power Analyzer to continually measure and refine the application for energy efficiency.
- Size storage type and capacity:
- With a full understanding of energy budget and key energy-consuming parameters, the storage element can be selected. Unlike conventional batteries, capacitor-based storage can be customized for the exact energy needs. Capacitor solutions come in various technologies, form factors and costs compatible with the MG22E Explorer Kit Shields screw-in terminals.
- IoT protocol selection and energy algorithm implementation:
- Most importantly, the IoT SoC is where Ambient IoT truly takes off. The MG22E is Silicon Labs’ lowest power and most platform-optimized SoC supporting multiple 2.4GHz protocols (Bluetooth LE, Zigbee Green Power, ad proprietary 2.4GHz). At the basis of these protocols is the Silicon Labs RAIL protocol which offers radio abstraction capabilities. For beaconing devices, the protocol’s payload, Tx power, PHY, and sleep interval can be dynamically adjusted based on platform energy-measurements.
Overview of the MG22E Shields with e-peas
We envision a future where IoT end-devices can be adapted to become battery-less. To achieve this, Silicon Labs is greatly lowering the technical barrier for energy-harvesting to the mass market so that all developers -- from students to experts -- can easily and enjoyably create more sustainable projects. The kit has been designed to be versatile to allow engineers to explore (and measure) a multitude of power sources, storage elements, and IoT protocols and also offers MikroBus and qwiic connector capabilities to integrate sensors.
e-peas is soley dedicated to creating circuitry to address ambient energy sources and they 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. It is their 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!
| Example | 协议 | Device Type |
|---|---|---|
| Energy Harvesting Sensor | 蓝牙 LE | 传感器 |
| Energy Harvesting Sensor | Bluetooth RAIL | 传感器 |
| Energy Harvesting Sensor | Zigbee 绿色电源 | 传感器 |
| Energy Harvesting Switch | Zigbee 绿色电源 | Switch |
| Energy Harvesting Switch | Bluetooth RAIL | Switch |
| Energy Harvesting Observer | 蓝牙 LE | Reader |
Each example has a thorough README that highlights the firmware’s behavior 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 on Silicon Labs Community for direct support.
结论
At Silicon Labs, we are dedicated to innovation and driven by our commitment to staying ahead of the curve, helping pave the way for an to ecologically responsible future of IoT. Our collaboration with e-peas to develop the Explorer Kit shield is another step in our commitment to advancing and innovating technology while striving for environmental sustainability. We are pleased to have expanded our wireless portfolio with one of the most energy-efficient, multi-protocol wireless SoC – the xG22E.
For more information, please check out our webpage, our blog on Ambient IoT and our most energy-optimized wireless SoC, the xG22E, or contact us.
