High Performance Microcontrollers: Key benefits & Applications

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Suited to simplifying the design of high-performance controls and user interfaces

Around four and half decades ago in 1971, Gary Boone and Michael Cochran from Texas Instruments had developed world’s first microcontroller TMS1000 which featured a ROM, RAM processor and an on chip clock. This product was launched in the market by 1974 for targeting multiple embedded applications. After seeing its success in embedded applications, many semiconductor companies further developed MCUs with diverse memory configurations and additional peripheral sets.

After the ROM based MCU, there were MCUs offered with erasable EPROM (Erasable Programmable Read-Only Memory) program memory with a transparent quartz window within the lid of package. This window allowed the erasing of the MCU program(s) by exposing it to ultraviolet light. During this period, semiconductor manufacturers made similar MCUs in two offerings: one based on EPROM and the other one with ROM. These offerings made the R&D on MCUs simpler as the engineers could use this EPROM based MCUs conveniently and post finalizing the software for production, they used to go ahead with a ROM based MCU. EEPROM (Electrically Erasable Programmable Read-Only Memory) was then introduced and in 1993, Microchip introduced the electrically erasable PIC16x84 series. In the same year Atmel introduced the flash based MCU. Since then, industries have seen a vast development in the areas of MCU area WRT processing (8à32 bits), memory capacity and rich peripheral sets.

Seeing the success of these products in the market, many semiconductor vendors (e.g. STMicroelectronics, Renesas, Zilog, Motorola, TI, Si-Labs, etc.) developed and launched their proprietary core based 8 and 16 bit MCUs with smart peripherals targeted for catalog and specific markets. Currently there are around 40 suppliers tending to more than 50 architectures in the market. In parallel, companies like ARM and MIPS delivered the standard 32 bit core to various Semiconductor companies for developing performance based MCUs around this. Till about early 1994, semicons couldn’t attract many customers towards their core offerings but after the introduction of the ARM7 core, ARM changed the market to a great extent.

The ARM7 processor core was immensely successful and established ARM as the architecture of choice in the digital world. Over the years, more than 10 million ARM7 based.

MCUs have powered a variety of applications. With the success of ARM7, ARM vendors, third party software companies and its customers have created a huge ecosystem for Software and Hardware tools for ARM architecture, making ARM the first choice for customers across markets. ARM7 is a Von Neumann architecture with nondeterministic interrupted behavior. Over the years, ARM has further developed their processor core offerings and has come out with their Cortex series.

ARM7

Around 2004 ARM announced the first microcontroller version of the Cortex series, the Cortex M3 and since then, has announced seven versions of the series:

Year Core
2004 Cortex-M3
2007 Cortex-M1
2009 Cortex-M0
2010 Cortex-M4
2012 Cortex-M0+
2014 Cortex-M7
High performance       Feature rich
  • Power efficient 32-bit processors
  • Support for sleep modes
  • Low power design with further optimization packs available
  • Low power consumption enables longer battery life
  • Instructions to support sleep modes
  • Program in C/C++, easy software reuse
  • Wide range of tools available
  • Standardize software framework (Cortex-M Software Interface Standard)
  • Free DSP library
High performance       Feature rich
  • Leading MCU performance
  • Instructions for bit manipulation
  • Low interrupt latency
  • Powerful DSP extensions and optional hardware Floating Point Unit
  • Powerful Interrupt Control with NVIC
  • OS support features
  • Memory Protection Unit (MPU)
  • Comprehensive debug and reliability features
Ecosystem        Reduced system size
  • Largest ecosystem in the industry
  • Several thousands of MCU catalog parts
  • Wide range of development suites
  • Wide range of middleware & RTOS
  • Low gate count
  • High code density reduces memory size
  • Smaller area reduces die cost
  • Smaller area reduces chip package size

There are more than 175 ARM partners for the Cortex M series which includes some major MCU suppliers like Analog Devices, Texas Instruments, Cypress, Atmel, NXP, Maxim, Nordic, Infineon, etc.  There are different applications powered by different specifications of the Cortex M based MCU.  Few trends in high performance applications are:

High performance MCU with rich connectivity: In the modern era of IOT, Embedded engineers are looking to create applications with further connectivity options. Embedded engineers are looking at giving a 200% extra connectivity option in their applications keeping in mind, its future usage. With a performing core like the ARM cortex M4, many semiconductor vendors have introduced a heap of connectivity peripherals. One such example is the Tiva Series from Texas Instruments. The Tiva Series offers MCUs in two variants: the TM4C123x and the TM4C129x.

The TM4C129x series uses Cortex-M4F core of 120MHz with FPU, MPU and ETM.  It has the features of a 1MB flash and a 256KB RAM making it suitable for any complex algorithm. Its

peripherals like the EPI, LCD and Analog make it suitable for industrial panels and sensors applications. With the connectivity option of 8 UART, 4 SPI, 10I2C, 2 CAN, USB OTG and a 10/100 Ethernet MAC and PHY, it is suitable for any high performance wired connected IOT application.

With a rich ARM ecosystem, the TM4C129x series offers a user friendly software development environment. With Tivaware, TI offers a range of libraries, like the Peripheral Driver Library, USB library, Graphics Library and Third Party Stacks with multiple examples as instructions to using the software. It helps application developers in developing any application on a fast track basis for the market.

High Performance MCU with optimized power: As the market is constantly growing for IOT applications, there is demand for each individual node, which might be running on battery to be cloud connected. For this reason, while the market requires better power performance, it also continuously demands more functionality from the devices. The challenge many developers face today is maintaining or improving battery operating life while simultaneously increasing a device’s capabilities. Adding to this challenge are the tightly constrained energy limitations placed on designs. For many devices, it is not feasible to increase battery size or capacity; this means that the developers need to achieve higher performance within the same power footprint if battery life is not to be compromised. In addition to these challenges, the market demands new product releases to meet aggressive deadlines, even though system design continues to become more complex simultaneously. Developers need a comprehensive set of hardware and software tools that enable them to extract maximum performance at the lowest possible power.

Finally, there needs to be room for future expansion as applications continue to integrate greater functionality. As MCU portfolios expand to address these needs, there must be seamless portability of both driver-level and application code across platforms.

TI has recently expanded the low-power foundation of its MSP430 MCU platform to include higher performance levels without sacrificing power budgets. Based on the 32-bit ARM® Cortex®-M4F core, the new MSP432 MCU platform leverages TI’s low-power design expertise to provide maximum performance with optimal energy efficiency. This MCU is the most power-efficient Cortex-M4F-based platform available today, with a ULPBench score of 167.4. The MSP432 MCU platform also offers embedded developers a complete silicon, software and ecosystem solution that enables them to bring innovative products to the market quickly. With the addition of the MSP432 MCU platform, the MSP MCU product line now provides a complete portfolio, from ultra-low power 16-bit flash and FRAM-based MCUs to high performance, low power 32-bit ARM Cortex-M4F devices. The MSP432 MCU platform is built around the high performance ARM Cortex-M4F core, featuring DSP extensions and an integrated floating-point engine.

MSP432 MCU

Integration of MSP peripherals with the Arm Cortex- M4F core: TI offers distinct advantages with the MSP432 series as mentioned below:

  • 32 bit performance
  • Four time power efficiency with CoreMark score 3.41
  • Integrated signal processing with inbuilt FPU
  • 128 bit Flash buffer pre-fetch
  • 1 MSPS 24 channels 14 bit ADC
  • 8 Channels DMA
  • Bit banded SRAM and Peripheral access
  • Integrated LDO/DC-DC for powering core
  • Wide operating Voltage Range
  • Flexible Power saving modes
  • Fast time to wake
  • Selectable Ram retention

These features make MSP432 suitable for any high performance low power applications. With a score of 167.4 ULPMarks, the MSP432 MCU platform achieves the highest ULPBench score for any Cortex-M3 or Cortex-M4F MCU available today. This means it provides more performance for the power than any other processor of its type in the industry, including Cortex-M0+, -M3, -M4, and -M4F cores or other 8-, 16- and 32-bit proprietary cores.

Wireless MCU: With the demand of IoT in the market, there is an increase in the number of applications where developers look for wireless connectivity. In earlier days, semiconductor vendors used to offer transceivers majorly interfaced on SPI/UART with Microcontroller for catering to this market requirement. But with trends of standardization for technology in wireless domains such as Wifi, Zigbee, BLE, 6lowPAN etc., developers are looking for semiconductor vendors for stack offering of these technologies with their transceivers. It was really difficult to maintain these technologies’ stack offering for all processor architecture available in the market. Hence, semiconductor suppliers have started offering the wireless SOC option. With the ARM cortex M introduction in the market, semiconductor vendors have majorly started working on wireless MCUs with ARM Cortex M core.

TI has recently released their Simplelink wireless MCU portfolio supporting almost all different technologies standard in wireless domain including Wifi, BLE, Zigbee, 6LowPAN, with 2.4GHz & SubGHz devices. Its CC2650 and CC13xx are the first Multi standard wireless MCU platform for IoT.

CC2650 and CC13xx

The CC26xx/CC13xx series of Wireless MCUs has three cores inside single MCU. Its 48MHz Cortex M3 core is main CPU core supported by Cortex M0 for RF and a proprietary sensor microcontroller. This Sensor controller with other peripherals make this MCU ideally suited for any battery powered IoT applications. The key features of Simplink wireless MCUs are:

Ultra-low Power Consumption

  • 61 µA/MHz ARM Cortex M3
  • 2 µA/MHz Sensor Controller
  • 1 µA sleep with retention and RTC
  • 9 mA RX (single-ended)
  • 1 mA TX (single-ended)
  • <3uA while running 10 ADC samples/s

SoC Key Features

  • Autonomous sensor controller engine
  • 4×4, 5×5, and 7×7 mm QFN
  • 7 – 1.95 V or 1.8 – 3.8 V supply range
  • 128 KB Flash + 8 KB Cache
  • 20 KB RAM

RF Key Features

  • +5/+14 dBm output power (2.4GHz/Sub1GHz)
  • -97/-120 dBm sensitivity (2.4GHz/Sub1GHz)
  • Supports 2.4GHz and 915/868/433 MHz
  • Pin compatible and SW compatible across protocols and frequency bands
Ultra-low power
When Parameter @ 3V Value
While processing µA/MHz on ARM® Cortex®-M3 61 µA/MHz
Coremark / mA 48.5
Coremark @ 48MHz CPU 142
While communicating Peak current RX 5.9 mA
Peak current TX 6.1 mA
While sleeping µA/MHz on  Sensor Controller 8.2 µA/MHz
Sleep mode with RTC and full memory retention 1 µA
    Best-in-class ULPBench score of 143.6

High Performance MCUs :By

Vikas Chola, EP Applications Manager – North India, Texas Instruments

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