MCUs combine Cortex-M7 core & advanced peripherals

25th June 2015
Barney Scott

STMicroelectronics has become the first chip maker to begin volume production of MCUs featuring the ARM Cortex-M7 processor: the latest and highest-performing Cortex-M core for advanced consumer, industrial, medical, and IoT devices. The smart architecture of ST's STM32F7 microcontrollers combines the Cortex-M7 core with advanced peripherals.

The MCU range offers product designers unrivalled opportunities to enhance application performance, add functions, extend battery life, ensure security, and minimise use of external components to save cost and size. The architecture also saves time usually spent optimising code performance and length, to allow extra focus on creating differentiating features in the end product.

To enable a large diversity of applications, the STM32F7 Discovery Kit comes with the comprehensive STM32Cube firmware library, as well as direct support from a wide ecosystem of software-development tool partners and the ARM mbed online community. The Discovery Kit's open hardware exposes the STM32F7 assets through an affordable compact design (priced at $49.90) including WQVGA touchscreen colour display, stereo audio, multi-sensor support, security, and high-speed connectivity. Together with an integrated ST-Link debugger/programmer (no need for a separate probe), unlimited expansion capability is provided through the Arduino Uno connectivity support and immediate access to a large choice of specialised add-on boards.

The STM32F7 devices are in production now, in a range of package options from a 14mm2 LQFP100 to 28MM2 LQFP208, plus 10mm2 0.65mm-pitch UFBGA176, 13mm2 0.8mm-pitch TFBGA216, and 5.9x4.6mm WLCSP143. Prices start from $6.73 for the STM32F745VE in 100-pin LQFP with 512KB on-chip Flash, for orders of 1000 units.

STM32F7 microcontrollers maximise the advantages of the Cortex-M7 core over earlier cores such as the Cortex-M4. It has about twice the DSP capability for applications requiring high-speed or multi-channel audio, video, wireless, motion recognition, or motor control. It is also the first Cortex-M core to feature on-chip cache, and is capable of ultra-fast data transfers and high-performance execution from embedded Flash or from external memories such as dual-mode Quad-SPI. These Cortex-M7 advances are combined with known strengths of the STM32 family, such as power efficiency, pin, peripheral and software compatibility across more than 500 different device variants, and the extensive STM32 development ecosystem.

Integrated with the Cortex-M7 core, ST's advanced peripherals have features such as a dedicated power rail for the USB OTG peripheral, which enables USB connectivity to continue operating while the rest of the chip is powered at 1.8V to save power. The dual clock domain on most peripherals allows the CPU speed to be reduced to minimise power consumption, while keeping the clock frequency unchanged on the communication peripherals.

ST has so far introduced two STM32F7 product lines. The STM32F745 and STM32F746/756 all feature the Cortex-M7 core with floating-point unit and DSP extensions, running at up to 216MHz. The devices deliver high processing efficiency of up to 6 CoreMark/mW at 1.8V. At the same time, typical current in Stop mode, with all SRAM saved, is only 100µA: similar to that of STM32F469 devices based on the Cortex-M4 core. Such outstanding power efficiency is achieved through ST's 90nm process, unique ART Accelerator graphic engine that reduces Flash access time, and advanced voltage scaling and underdrive/overdrive that help optimise speed and power consumption.

The STM32F745 has up to 1MB of Flash memory on-chip, as well as 320KB RAM, Ethernet, QSPI and camera interfaces, and a Flexible Memory Controller (FMC). The STM32F76 extends the functionality by integrating a TFT-LCD controller on-chip. The STM32F756 has the same features as the STM32F746 with the addition of a crypto/hash processor providing hardware acceleration for AES-128/-192/-256, with support for GCM and CCM, Triple DES, and hash (MD5, SHA-1 and SHA-2).

"ST's first-to-market advantage and industry-leading architecture and feature integration enable our customers to deliver outstanding products into their own target markets," said Daniel Colonna, Marketing Director, Microcontroller Division, STMicroelectronics. "Moreover, the strength of our development environment, including immediate availability of the STM32F7 Discovery Kit and firmware, allows rapid design cycles."

The STM32F7 development ecosystem includes both the Discovery Kit and two evaluation boards, STM32746G-EVAL2 and STM32756G-EVAL2, priced at $560 each. The STM32F7 Discovery Kit (STM32F746G-DISCO) gives full flexibility to fine-tune hardware and software at any stage of development, which minimises financial risks. Developers also benefit from the associated STM32CubeF7 firmware, and the ability to re-use all STM32F4 software assets due to code compatibility.

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