Arm-ed for Success
32-bit microcontrollers have become entrenched as the workhorse of today’s embedded systems. These devices serve a wide variety of embedded applications—adding intelligence, security and connectivity to today’s “smart” systems.
For years, 32-bit devices have defined the top of the microcontroller (MCU) food chain, providing a mix of processing, memory and I/O on a single chip. They are essentially the most advanced engine for embedded systems before moving onto to a microprocessor (MPU)-type device, and all the baggage MPUs bring with them. And as embedded systems have evolved, so too have 32-bit MCUs. The most significant trends in recent years have been the addition of wireless connectivity and advanced security
Today’s crop of MCUs has many product offerings that include on-chip wireless connectivity. This has taken the form of support for Bluetooth Low Energy (BLE), Wi-Fi and other technologies. With MCUs designed into systems across a wide diversity applications and industries, it’s hard to make any general statement about how they are used these days. But the leading MCU application areas include automotive, industrial systems, IoT, smart city, smart home, wearable devices and medical gear.
An ongoing trend among 32-bit MCUs is the dominance of products based on Arm Cortex CPU cores. While the leading vendors each offer successful lines of 32-bit MCUs based on their own proprietary cores, Arm-core based MCUs have clearly dominated new product rollouts over the past 12 months. In fact, in this article’s product gallery you’ll notice that seven out of the nine representative 32-bit MCUs are based on some form of the Arm Cortex CPU core (or cores).
Healthcare wearables is one of the most dynamic areas of 32-bit MCU design today (Figure 1). With that in mind, Maxim Integrated included its most recent 32-bit MCU product in its Health Sensor Platform 3.0 (HSP 3.0) that it announced last Fall. This ready-to-wear wrist form factor reference design monitors blood oxygen saturation, electrocardiogram, heart rate, body temperature and motion.
Maxim’s HSP 3.0 or MAXREFDES104# includes sensor, power management, MCU and algorithm products. The MCU is the MAX3266, a BLE-enabled, ultra-low power MCU with two Arm Cortex-M4F cores and an additional SmartDMA which permits running the BLE stack independently, leaving the two main cores available for major tasks
PUBLISHED IN CIRCUIT CELLAR MAGAZINE • MAY 2021 #370 – Get a PDF of the issue
Secure MCUs Feature Full IoT Lifecyle Management
The PSoC 64 Secure MCUs from Cypress Semiconductor (now part of Infineon Technologies) integrate the ultra-low power PSoC 6 architecture with well-structured open-source IoT platform software to deliver a secure solution. The MCU is supported with Trusted Firmware-M embedded security, the Arm Mbed IoT OS and the Arm Pelion IoT platform.
• 32-bit Arm Cortex-M4 CPU
• Complies with Bluetooth 5.0
• Support for BR, EDR 2Mbps and 3Mbps, eSCO
• BLE and LE 2Mbps
• 256KB on-chip secure flash; 176KB on-chip RAM
• AES-128 and TRNG
• Up to 40 GPIOs; I2C, I2S, UART and PCM interfaces
• Two Quad-SPI interfaces
• Auxiliary ADC with up to 28 analog channels
Automotive MCU Targets Next-Gen Vehicles
The multicore Traveo II Body family of MCUs from Infineon Technologies is based on Arm Cortex-M7 and -M4 cores with up to 8MB of embedded flash that helps the devices deliver the high performance required for demanding automotive body electronics applications. Compliance to ISO26262 ASIL-B Level ensures a safe operation of the device, even for ambient temperatures up to 125°C.
• Integrated 350MHz Arm Cortex-M7 dual core
• 3 SAR ADC units
• 8MB flash memory
• 3.3V to 5.5V supply with power-on-reset
• Up to 10-ch CAN FD, up to
11-ch SCB, up to 20-ch LIN-UART
• 15-ch motor control
• Up to 2-ch 10/100/1000-Mbit Ethernet
IoT MCU Provides PUF Key Protection Tech
The MAX32666 from Maxim Integrated is an ultra-low-power dual Arm Cortex-M4 MCU with floating-point unit (FPU) and Bluetooth Low Energy 5.2 (BLE 5.2). It extends battery life by combining robust memory, security, communications, power management and processing functions traditionally performed by multiple MCUs into a single device.
• Arm Cortex-M4 with FPU up to 96MHz
• Optional 2nd Arm Cortex-M4
• 1MB flash, organized into dual banks
• 560KB SRAM; 3x 16KB Cache
• Bluetooth 5 Low Energy radio
• Integrated SIMO SMPS for coin-cell operation
• TPU with MAA supports Fast ECDSA and modular arithmetic
• AES128/192/256, DES, 3DES, hardware accelerator
• Secure bootloader
MCUs Target Motor Control Designs
The PIC32MK MCM MCUs for field-oriented control (FOC) from Microchip Technology are second-generation 32-bit MCU devices that offer 32-bit floating point and DSP performance with flexible communications options. By sharing analog features with Microchip’s dsPIC33CK, they support seamless migration across device classes. These devices also feature multiple CAN-FD and USB ports.
• 120MHz MIPS32 microAptiv core
• Up to 1M flash with ECC, dual-panel; Up to 256KB SRAM
• 12-bit ADC modules, 12-bit DAC modules
• Fast-response comparators,
high-bandwidth op amps
• PWM and QEI peripherals for motor control
• Up to 4x CAN FD, Up to 4x full speed USB
• Up to 6x UART modules, Up to
6x SPI/I2S modules
• AEC-Q100 Qualified
Low Power MCU for Industrial Control
Nuvoton Technology’s NuMicro M251 /M252 series designed for industrial control applications. It is based on an Arm Cortex-M23 secure core for Armv8-M architecture, running up to 48MHz with up to 256KB flash and up to 32KB SRAM. The power consumption in the deep power-down mode is down to 2.0μA. NuMicro M251/M252 Series provides five kinds of power modes and three kinds of secure protection mechanisms.
• Arm Cortex-M23 secure core for Armv8-M
• Up to 256KB flash and
up to 32KB SRAM
• Deep power-down mode is
down to 2.0μA
• Supply voltage ranges from
1.8V to 5.5V
• Operating temperature range:
-40°C to 105°C
• Rich package options types from 20 pins to 128 pins
• 5 power modes for different operating scenarios
• Integrated RTC with independent VBAT
• UART supports rates up to 9600bps in power down mode
MCUs Ease Automotive Software Development
NXP Semiconductors’ S32K3 family of 32-bit Arm Cortex-M7-based MCUs are designed for automotive body electronics, battery management and emerging zone controllers. The MCUs simplify software development with an enhanced package that spans security, functional safety and low-level drivers. Features include a hardware security engine with NXP firmware, support for firmware over-the-air (FOTA) updates.
• Single, multiple, or lockstep Cortex-M7 cores, 120-240MHz + FPU
• 512KB-8MB flash with ECC
• FOTA–A/B firmware swap with zero downtime
• 12-bit 1Msps ADC
• 16-bit eMIOS timer with logic control unit for motor control
• Low-power Run and Standby modes
• MaxQFP and BGA packages
• -40°C to 125°C operating temperature
• ISO 26262 up to ASIL B/D
• Fault Collection and Control Unit
MCU Boasts Rich Communications Options
Renesas Electronics’ RA6M5 MCU group embeds the high-performance Arm Cortex-M33 core with TrustZone. In concert with the Secure Crypto Engine, it offers Secure Element functionality. The integrated Ethernet MAC with individual DMA ensures high data throughput. The RA6M5 is built on a highly efficient 40nm process and is supported by an open and flexible ecosystem concept.
• 200MHz Arm Cortex-M33 with TrustZone
• 1MB – 2MB flash memory and
• Scalable from 100-pin to 176-pin packages
• Ethernet controller with DMA
• Capacitive touch sensing unit
• USB 2.0 High-Speed and Full Speed
• CAN FD (CAN 2.0B option)
• QuadSPI and OctaSPI
• SCI, SPI/ I2C multimaster interface
• SDHI and MMC
Wireless MCUs Offer Entry-Level Features
The STM32WB15CC from STMicroelectronics is multiprotocol wireless and ultra-low-power MCU device that embeds a powerful and ultra-low-power radio compliant with the BLE SIG specification v5.2. It contains a dedicated Arm Cortex -M0+ core or performing all the real-time low layer operation. The device is designed to be extremely low-power and is based on the high-performance 64MHz Arm Cortex-M4 32-bit core.
• 64MHz Arm Cortex-M4 32-bit core
• 320KB flash memory, 48KB of SRAM
• 7 DMA channels with a mapping by DMAMUX peripheral.
• AES encryption engine
• 1x 12-bit ADC and 1x low-power comparator
• Low-power RTC, advanced 16-bit timer
• Up to 8 capacitive sensing channels
• 1x USART, 1x LPUART), 1x I2C,
• -40°C to +105°C temperature range
MCU Family Adds EtherCAT, Ethernet and CAN FD
The TMS320F2838x from Texas Instruments is a 32-bit floating-point MCU designed for advanced closed-loop control applications. The integrated analog and control peripherals with advanced connectivity peripherals like EtherCAT and Ethernet let designers consolidate real-time control and real-time communications architectures, reducing requirements for multi-controller systems.
• Dual-core 200 MHz C28x architecture
• IEEE 754 double-precision (64-bit) FPU
• 512KB of flash on each CPU
• 44KB of local RAM on each CPU
• EtherCAT slave controller (ESC)
• 10/100 Ethernet 1588 MII/RMII
• USB 2.0 (MAC + PHY)
• 2x CAN modules (pin-bootable)
• 4x ADCs, 8x windowed comparators with 12-bit DAC references
Jeff served as Editor-in-Chief for both LinuxGizmos.com and its sister publication, Circuit Cellar magazine 6/2017—3/2022. In nearly three decades of covering the embedded electronics and computing industry, Jeff has also held senior editorial positions at EE Times, Computer Design, Electronic Design, Embedded Systems Development, and COTS Journal. His knowledge spans a broad range of electronics and computing topics, including CPUs, MCUs, memory, storage, graphics, power supplies, software development, and real-time OSes.