Suited for wide variety of applications, 32-bit microcontrollers continue to be the workhorse device for today’s embedded application. To keep pace, MCU vendors are evolving their product lines with robust security, rich I/O functionality and support for all the popular wireless protocols.
Today’s crop of 32-bit MCUs are the fruit of decades of evolution and innovation, taking advantage of Moore’s Law to keep increasing chip capabilities. Among the most dynamic trend in MCUs over the past couple years has been the integration of wireless connectivity. Driven mostly by the fast-growing Internet of Things (IoT) phenomenon, today’s new generation of MCUs includes many product offerings that include support for Bluetooth Low Energy (BLE), IEEE 802.15.4g, 6LoWPAN and other technologies. Because MCUs are embedded in systems across a wide diversity applications and industries, you can’t really generalize about how they are used. Automotive, industrial systems, smart city, smart home, wearable devices and medical gear are among the leading MCU application areas—but there are a whole host of other segments.
An example of a 32-bit MCU application is livestock position and health monitoring (Figure 1). According to STMicroelectronics, the meat industry hopes to boost its efficiency and production by maintaining location and activity data for every animal in the field. Positioning and tracking applications rely on a core MCU operating with MEMS motion sensors to detect animal movement or changes in their position, a dedicated GNSS-based positioning chipset, and a connectivity block for transmitting the acquired data. For its part, ST says it can provide a complete solution for all kinds of animal positioning and tracking devices based on connectivity, geolocation and motion sensors. The company’s STM32 MCU based on low-power Cortex-M0 cores, or its ultra-low-power version (M0+), are well-suited to these challenging performance and power consumption requirements. MCU-based BLE provides seamless connectivity with smart phones for parameter analysis, data collection and parameter setting.
All of the leading vendors each offer extensive 32-bit products lines, each with many versions. With that in mind, the MCUs shown in the product gallery on the next couple pages are just a representative sampling today’s offerings.
MCU Has Integrated Power Management
The ADuCM4050 from Analog Devices is an ultra-low power integrated MCU system with integrated power management for processing, control and connectivity. The MCU system is based on the Arm Cortex-M4F processor. The MCU also has a collection of digital peripherals, embedded SRAM and flash memory, and an analog subsystem which provides clocking, reset and power management capability in addition to an ADC subsystem.
• Up to 52 MHz Arm Cortex-M4F processor
• 512 KB of embedded flash memory with error correction code (ECC)
• 128 KB system SRAM with parity
• Power management unit (PMU)
• Multilayer bus matrix, central DMA controller
• Crypto hardware supporting AES-128, AES-256 and others
• Serial port, SPI, I2C and UART
• Real-time clock (RTC), generalpurpose and watchdog timers
• 12-bit SAR ADC
Low-Power MCU Supports Bluetooth Mesh Networking
The CYW20819 from Cypress Semiconductor is a Bluetooth 5.0-compliant, standalone baseband processor with an integrated 2.4 GHz transceiver with support for BLE, BLE 2 Mbps, EDR 2 Mbps and 3 Mbps, synchronous connection-oriented (SCO) and extended SCO (eSCO). The device is intended for use in audio, IoT, sensors and HID markets.
• 32-bit 98-MHz Arm Cortex-M4 CPU
• Complies with Bluetooth 5.0
• Support for BR, EDR 2 Mbps and 3 Mbps, eSCO,
• BLE and LE 2 Mbps
• 256-KB on-chip secure flash; 176-KB 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
Flash MCU Provides EtherCAT Slave Interface
Infineon Technologies’ XMC4800 is a flash-based Arm Cortex-M MCU series that provides an EtherCAT slave interface with a 100 Mb/s data-transfer rate. It has two MII ports for EtherCAT, eight fieldbus memory management units, eight sync manager units and 64-bit distributed clocks. The MCU featured in the Amazon Web Services FreeRTOS kit is an XMC4800- F100x2048.
• 144 MHz Arm Cortex-M4 core
• 2 MB of flash; 353 KB of RAM
• 100-pin package
• On-board debugger
• LED and touch-sense controller
• SD and Multi-Media Card interface
• Four 12-bit ADCs
• Delta-sigma demodulator
• Two-channel, 12-bit DAC
MCU Has Always-On Features for Wearable Designs
The MAX32625/MAX32626 from Maxim Integrated is MCU based on Arm Cortex-M4 with FPU. It's well suited for the emerging category of wearable medical and fitness applications. An internal 96 MHz oscillator provides high-performance capability, and the internal 4 MHz oscillator supports minimal power consumption for applications requiring always-on monitoring.
• Internal oscillator operates up to 96 MHz
• Low power 4 MHz oscillator system clock option for Always-On monitoring applications
• 512 KB flash memory, 160 KB SRAM
• 1.2 V core supply voltage; 1.8 V to 3.3 V I/O
• Wide operating temperature: -30°C to +85°C
• 106 μA/MHz executing from cache; 49 μA/MHz executing from flash
• Wake-up to 96 MHz clock or 4 MHz clock
• Peripheral mix provides SPI, I2C, USB and more
• 10-bit delta-sigma ADC
MCU Provides Enhanced Security for IoT Systems
The SAM L10 and SAM L11 MCU families from Microchip Technology are based on the Arm Cortex-M23 core, with the SAM L11 featuring Arm TrustZone for Armv8-M, a programmable environment that provides hardware isolation between certified libraries, IP and application code. Security features on the MCUs include tamper resistance, secure boot and secure key storage.
• 32 MHz Arm Cortex-M23 core
• Up to 64 KB flash; 16 KB SRAM
• Enhanced Peripheral Touch Controller
• ARM TrustZone and TRNG (L11 only)
• Crypto accelerators: AES, SHA and GC (L11 only)
• 24- and 32-pin package options
• Under 25 μA/MHz active; under 100 nA sleep
• Fast wake up times: 1.5 μs
• “SleepWalking” peripherals
Low-Cost Flash MCU Targets IoT Edge Applications
NXP Semiconductors’ LPC5500 MCUs combine single- or dual-core Arm Cortex-M33 cores and Arm TrustZone technology. Built on a low-power 40 nm embedded flash process, the LPC5500 MCU achieves 32 μA/MHz efficiency at up to 100 MHz core clock frequency. Devices within the LPC55S6x family are starting at a per unit price of $1.99 for 256K B flash and $2.49 for 640 KB flash, in 10,000-unit quantities.
• Arm Cortex-M33 core
• Up to 640 KB flash: 320 KB on-chip SRAM
• for advanced edge applications.
• 16-bit SAR ADC) with differential pair mode
• SPI, USB, 8x FlexComm, 2x SDIO
• Dedicated co-processor interface
• Secure boot, SRAM PUF based unique key storage
• Certificate based secure debug authentication
• AES-256 and SHA2-256 acceleration
Automotive Flash MCU Features Virtualization
Renesas Electronics’ RH850/U2A16 MCU is a member of Renesas’ crossdomain MCUs, a new generation of automotive-control devices, designed to address the growing need to integrate multiple applications into a single chip to realize a unified electronic control units (ECUs) for the evolving electrical electronic architecture (E/E architecture).
• Four 400 MHz lockstep cores (RH850 G4MH core)
• Hardware-based virtualization
• Self-diagnostic SR-BIST
• Secure OTA updates
• 16 MB of flash ROM; 3.6 MB of SRAM
• Evita Light support up to Evita Full
• SGMII-standard 1 Gbps Ethernet
• 16 channel CAN-FD interface
Provide Real-Time Capability
Dual-Core Wireless MCUs The STM32WBx5 dual-core wireless MCUs from STMicroelectronics come with Bluetooth 5, OpenThread, and ZigBee 3.0 connectivity combined with ultra-low-power performance. They combine the features of ST’s STM32L4 Arm Cortex-M4 MCUs and in-house radio managed by a dedicated Cortex-M0+. It is well suited for remote sensors, wearable trackers, building-automation controllers, computer peripherals, drones and other IoT devices.
• 64 MHz Arm Cortex-M4 core
• 32 MHz Arm Cortex-M0+ core (network processor)
• Bluetooth 5 and IEEE 802.15.4 support
• Bluetooth Mesh 1.0 network support
• USB 2.0 FS interface, audio support, LCD driver
• Up to 72 GPIOs, integrated SMPS
• 256-bit AES hardware encryption
• PCROP read/write protection
• JTAG fuse and public-key cryptography
Crystal-less BAW Multiprotocol 2.4-GHz Wireless MCU
Texas Instruments’ CC2652RB BAW (bulk acoustic wave) device is a multiprotocol wireless 2.4-GHz MCU targeting Thread, Zigbee, Bluetooth 5 Low Energy, IEEE 802.15.4, IPv6-enabled smart objects (6LoWPAN), Wi-SUN. Very low active RF and MCU current, in addition to sub-μA sleep current with up to 80 KB of RAM retention, provide excellent battery lifetime and allow operation on small coin-cell batteries in energy-harvesting applications.
• 48-MHz Arm Cortex-M4F CPU
• Dedicated Radio Controller (Arm Cortex-M0)
• 352 KB of flash, 256 KB of ROM
• 80 KB of SRAM wit parity
• Supports Over-the-Air Upgrade (OTA
• Complete RF system and an on-chip DC/DC converter
• Integrated BAW eliminates need for externa 48-MHz crystal.
• Sensor Controller CPU with 4 KB of SRAM
• Fast wake-up and ultra-low-power 2-MHz modes