ARM unveils Cortex-M7 core, doubles compute and DSP performance of M series
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In a move which doubles the compute and digital signal processing power of the most powerful cores in its Cortex-M MCU family, ARM has launched the Cortex-M7. The core, targeted at high end embedded applications, has already been licensed by Atmel, Freescale and ST Microelectronics.
The Cortex-M architecture has been upgraded such that the core can run at 5CoreMark/MHz. Ian Johnson, Cortex-M7 product manager, said using this core would create some of the highest performing MCUs currently available. "But the core and the instruction set architecture remains compatible with other members of the Cortex-M family."
The performance available from the M7 core has been achieved through the use of a six stage superscalar pipeline design, which includes a branch predictor. "Previously," Johnson said, "M cores had only two or three stages. When manufactured on a 40nm low power process, the core will be able to run at 400MHz, with a processing power of 2000CoreMarks. This goes beyond what would be achieved using a process shrink alone and the core still hits the 12 cycle interrupt latency target." The device is also suitable for a 28nm process, which could result in an 800MHz part.
According to Johnson, one of the design targets was to produce a core suitable for use in safety critical applications. "There has been substantial effort to add hardware features which support safety critical, including the addition of ECC memory and documentation of the processor. ARM hasn't done this with previous cores, so it marks a new direction."
Operating in lock step, two M7 cores can operate with a two cycle delay between them. A reference implementation compares each core's operation.
The core will also feature the AXI AMBA4 interconnect as the default memory interface, although AHB ports will be available to support legacy parts.
Thomas Ensergueix, senior product marketing manager, noted that, since the launch of Cortex-M 10 years ago, more than 8billion cores have shipped, with more than 50% of them shipping in the last 18 months or so. "Almost 3bn shipped in 2013 and another 1.7bn in the first half of 2014. We have 240 licensees for the Cortex-M range and there are more than 3000 catalogue parts in the market."
Asked why there has been such an acceleration, Ensergueix pointed to a market that moves more slowly than the consumer world. "You need to convince people to change MCU architectures," he explained, "and that's what's happening now. The projects we're seeing going into volume were started in the last couple of years."
"Freescale Cortex-M7 based solutions extend MCU performance dramatically, opening new opportunities for our business," said Geoff Lees, general manager of Freescale's MCU group. "Our solutions will enable significant innovation and system-level efficiency in areas where the high performance of the Cortex-M7 core eliminates the need for additional DSPs and MCUs."
