Design Con 2015

It’s all about tools: developing power-sensitive, low current MCU designs

Parker Dorris and Paul Zucker, Silicon Labs

April 03, 2013

Parker Dorris and Paul Zucker, Silicon LabsApril 03, 2013

The developer can then visually determine which components are consuming the most power in that supply domain, and try to target configuration changes on those components. As an example, Figure 2 shows how clicking on the ADC’s pie slice opens a properties window that displays a list of configuration properties filtered to include only those properties whose changes will impact power consumption.



Figure 2: Drilling down for clarity and relevant configuration properties

Power Estimator also allows developers to take snapshots of a power mode while configuration is in-progress (Figure 3). Snapshotting gives developers a visual, easily interpreted method by which they can see how a set of configuration choices affects power consumption. Both windows displayed in the snapshot view can be explored by clicking on pie slices to drill down to expose more information as needed.



Figure 3: Snapshotting provides a visual reference point for comparing configuration choices

The Power Estimator tool has been optimized specifically to simplify configurations of some of the SiM3L1xx MCU’s key ultra-low-power features that can be onerous to configure manually (Figure 4). The default configuration of the Si3L1xx MCU leaves the dc-dc converter disabled, and the supply voltage is routed directly to the on-chip LDO. Directly applying a 3.3 V supply to the LDO will result in an efficiency loss of around 40 percent, which can be substantial in battery-powered applications.



Figure 4. SiM3L1xx MCU with supply directly routed to the LDO

However, the AppBuilder user interface provides a few easy-to-understand lists of properties that a developer can modify to enable the dc-dc converter and allow the LDO to use the dc-dc converter’s output as its input. (Figures 5 and 6) Power Estimator’s snapshotting tool makes the power savings gained through the use of the dc-dc converter easy to observe (Figure 7).



Figure 5: Configuring properties in AppBuilder software



Figure 6: Supply routing after configuration changes



Figure 7: Power savings illustrated using Power Estimator

A power-aware software tool simplifies difficult development tasks
Using a software tool like Power Estimator instead of jumping to iterative firmware development on a hardware platform means less time spent poring over a reference manual and less test setup frustration. Powered by a sophisticated modeling algorithm, Power Estimator’s visualization techniques for displaying component-by-component power consumption enable developers to see at a glance where their system power is being consumed.

The interactive charts and user interface design facilitate easy exploration and alteration of configuration choices, with every choice resulting in a real-time, reliable updates to power consumption information. The next time you embark on a challenging, power-sensitive embedded design, be sure to choose an MCU platform supported by easy-to-use power-aware tools that help simplify the task of minimizing system-level current consumption.

Note: Silicon Labs’ AppBuilder software provides a graphical view of hardware configuration and generates code when the configuration completes. This complimentary tool is deeply integrated with the Silicon Labs Hardware Abstraction Layer used to configure all peripherals as well as the Precision32 IDE, which is an Eclipse-based development environment with sophisticated debug features. AppBuilder checks for potential conflicts and errors with every configuration choice the user makes, and it provides helpful instructions on how to resolve issues as they arise. The tool gives developers an intuitive process by which they can create multiple operational modes, as well as a graphical display to configure gate clocks and port pin functionality.

Parker Dorris is a senior applications engineer supporting Silicon Labs’ microcontroller product line. He joined Silicon Labs in 2003 when the company acquired Cygnal Integrated Products. Mr. Dorris specializes in the areas of human interface and USB embedded system design. He holds a BSEE from the University of Texas at Austin.

Paul Zucker is a staff systems engineer at Silicon Labs, specializing in development tools, debug solutions and firmware development on the ARM platform. Mr. Zucker joined Silicon Labs in 2010 after working in various engineering roles at Freescale, SigmaTel, and AMD. He has more than 25 years of experience developing embedded systems from 8-bit bare metal designs to 32-bit embedded Linux systems and everything in between. He holds a BSEE from Washington University in St. Louis, Missouri, and a BA in mathematics from Doane College in Nebraska.

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