Rasmus’ tips for ARM Cortex-M energy efficiency #3.
Rasmus is a Support & Training manager at Energy Micro, supporting customers with technical articles, seminars, and video materials. He also operates “The Lizard Lounge” forum open to everyone to share engineering ideas and application design tips.
In a series of posts on the Energy Micro blog, I´ll take a closer look at some of the features that are available for ARM Cortex-M microcontroller users. I will also show you some examples how I normally use them, and how they can be helpful when trying to reduce the energy consumption in embedded applications.
In many battery-operated applications, there are often one or more periodic tasks to complete while the microcontroller is in active mode. The unneeded time between these processing events is placed in sleep mode, and you can minimize energy consumption of your application by increasing the amount of time in sleep mode as much as possible. Therefore it is tempting to reduce the clock frequency to the minimum required to complete the processing tasks each period. The drawback is of course that the savings in power consumption lead to proportionally longer processing time, and thus just as much energy is consumed.
With the EFM32 microcontroller, you can design power sensitive applications by spending as little time in active mode as possible. The Cortex-M3 architecture in the EFM32 was developed for response and power sensitive applications and is much more processing efficient than 8- and 16-bit CPUs. It allows you to crank up the frequency on your Cortex-M, complete tasks faster, and spend more time in an energy friendly sleep mode in between processing tasks.
Watch the 10 factors to reduce time in active mode:
Download a relevant white paper: EFM32 Introduction
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