The close partnership between ARM and Freescale, one of the Cortex-M0+ lead-partners, enabled them to be extremely fast in launching their first MCU series. The processor features also triggered the interest of many other partners and we expect more Cortex-M0+ processor-based products to come. To see why, one needs only to look at the processor features.
When the ARM Cortex™-M0+ processor was launched in March, many of the headlines focused on the lower power consumption and energy efficiency. If this was the only differentiator, then this new processor might perhaps have been called “Cortex-M0-“. In reality there is much more innovation in this product than lower power, and this new member of the Cortex-M family well deserves its “+”.
Through the success and the experience gathered with our fifty ARM Cortex-M0 processor licensees, it became clear there was a space to further extend the Cortex-M series offering for lowest cost devices. Our architecture team started to come up with very interesting concepts to optimize the implementation of the pipeline, while Freescale and NXP confirmed their interest to join as lead partners and to contribute to the specification with their long track record in the 8-bit arena.
The Cortex-M0 MCU was quite unique when launched in 2009, offering a subtle mix of low-power, 32-bit performance and optimized code size, all of this packed in a very low gate count processor. We often talk about having low power in our DNA and this applies very strongly to the Cortex-M space. The new implementation of the very same ARMv6-M architecture with a 2-stage pipeline in Cortex-M0+ has given us 9% more performance while reducing the power consumption by around 30%.
Beyond the obvious longer operating time on battery, this higher energy efficiency benefits lots of other applications. Lower consumption for a given task reducing overall power needs and the thermal dissipation. That in turn helps developers scale down the power supply and save cost and gives more clock frequency flexibility when running in high-temperature environment such as automotive.
Another big step forward with Cortex-M0+ MCUs is the enhanced debug, giving finally access to the convenience of Trace debugging to entry level systems. Up until now this “safety net” was reserved to higher class processors because the silicon and pin count overhead was not affordable. How many developers have burnt evenings and weekends, spending hours troubleshooting weird bugs because of missing visibility of the program execution? This sort of long and drawn out debug effort has to end, pressure on timelines and application complexity is going in only one direction: always higher. To keep the Cortex-M0+ slim and trim our engineers designed a very lightweight solution preserving the real time capability and keeping the implementation overhead to a minimum: just 1.5k gates of logic, no extra pins and sharing the RAM in a flexible manner with the application.
Freescale has just released an interesting video addressing these innovations and explaining exactly why the product warrants a “+”. I think it is great!
Thomas Ensergueix, CPU Product Manager, ARM. Thomas is leading the product management team in charge of the Cortex-M family of CPU as part of ARM’s processor division. Before joining ARM early 2012, he was active in the embedded area since the end of the 90’s, occupying multiple positions, and covered the whole spectrum of 8-bit to 32-bit architectures for smartcard ICs and microcontroller products.
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