STM32U5 Cortex-M33 MCU gets more performance, 2D graphics accelerator, and advanced security

The first STM32 MCU based on Arm Cortex-M33 core was the ultra-low-power STM32L5 microcontroller, and the company is now following up with the STM32U5 series also designed for smart applications including wearables, personal medical devices, home automation, and industrial sensors.

The new family has a higher 160 MHz clock speed, up to 2048 KB flash, up to 786 KB RAM, a 2D graphics accelerator, several peripherals have been upgraded, and a new autonomous mode lets DMA and peripherals keep working while most of the device sleeps in order to save power. STM32U5 MCUs also integrate additional hardware security features, and are manufactured using a 40nm process, which the company says is the most advanced process suitable for microcontrollers.

Just like for the STM32L5 family, there are two product lines in the STM32U5 series which mostly differ in their security features:

STM32U575 with 1024 to 2048 KB of flash memory, 786 KB RAM
STM32U585 with 2048 KB of flash memory, 786 KB RAM, and additional security features include AES-128/256, PKA, and on-the-fly decryption (OTFDEC)

Highlights of the STM32U5 family include:

MCU Core – Arm Cortex-M33 Armv8-M core clocked at up to 160 MHz with FPU, Arm TruztZone
Memory – 768 KB RAM
Flash – 1024KB to 2048KB flash
Chrom-ART accelerator (DMA2D) for 2D graphics
Mathematical co-processor – CORDIC for trigonometric functions
acceleration, FMAC (filter mathematical accelerator)
ST ART Accelerator – 8-KB instruction cache allowing 0-wait-state execution from Flash and external memories: up to 160 MHz, MPU, 240 DMIPS, and DSP
Peripherals
- USB – 1x USB OTG 2.0 full-speed controller, 1x USB type-C/PD controller
- 2x Analog-to-digital converter (ADC), one 14-bit, one 12-bit both up to 2.5 Mbps
- 2x 12-bit digital-to-analog converters (DAC)
- 2x ultra-low-power comparators
- 2x operational amplifiers with external or internal follower routing and programmable-gain amplifier (PGA) capability.
- 6x USART, 3x SPI, 4x I2C, 1x CAN-FD
- 16- and 32-bit timers
- 2x SAI + audio PLL
- 2x SDMMC interfaces
- Up to 24 capacitive touch sensing
Security – Arm TrustZone, flexible software isolation, secure boot, key storage, and hardware cryptographic accelerators:
- AES encryption and Public Key Authorization (PKA) are now hardware resistant to side-channel attacks by Differential Power Analysis (DPA)
- Hardware Unique Key (HUK) for secure data storage
- Active tamper detection
- Internal monitoring that can erase secret data in the event of perturbation attacks helps meet the PCI Security Standards Council (PCI SSC) requirements for Point Of Sales (POS) applications.
Power Features / Consumption
- Operating Voltage – 1.71 to 3.6 V
- Embedded SMPS step-down converter (optional)
- UCPD controller compliant with USB Type-C Rev. 2.0 and USB Power Delivery Rev. 3.0 specifications.
- Power consumption numbers:
  - 110 nA in shutdown mode (with 24 wakeup pins)
  - 300 nA Standby mode (24 wakeup pins)
  - 475 nA Standby mode with RTC
  - 1.7 μA Stop 3 mode with 16-Kbyte SRAM
  - 3.1 µA in stop 3 mode with full SRAM
  - 3.4 μA Stop 2 mode with 16-Kbyte SRAM
  - 6.6 µA in stop 2 mode with full SRAM
  - 19.5 µA/MHz in active mode @ 3.3V
  - Note: Stop 3 is the lowest power mode with full retention, but the functional peripherals and sources of wakeup are reduced to the same ones as in Standby mode.
Packages – LQFP48, UFQFPN48, LQFP64, WLSCP90, LQFP100, UFBGA132, LQFP144, and UFBGA169
Temperature Range – -40°C to +85°C or -40°C to +125°C

The options for flash capacity, HW crypto, and packages mean there are 15 different STM32U5 microcontrollers, albeit the parts with only 1MB flash will only become available later in Q3 2021.

Software and STM32U5 development board

The new STM32U5 microcontrollers will be supported by the STM32Cube software suite that includes Azure RTOS (aka ThreadX), STM32CubeMX, and STM32CubeIDE tools, as well as code examples. Third-party IDEs such as IAR Embedded Workbench and MDK-ARM are also supported.

STMicro is also offering an STM32U5 evaluation/development board with B-U585I-IOT02A Discovery Kit based on the STM32U585AI microcontroller (169-pin UFBGA, 2MB flash, HW crypto). Also known as the “STM32U5 IoT Discovery Kit”, the board is equipped with a Wi-Fi and Bluetooth module, microphones, a temperature and humidity sensor, a magnetometer, an accelerometer and gyroscope, a pressure sensor, as well as Time-of-Flight (ToF) and gesture-detection sensors.

The board also comes with 512-Mbit octal-SPI Flash memory, 64-Mbit octal-SPI PSRAM, 256-Kbit I2C EEPROM, as well as ARDUINO Uno V3, STMod+, and Pmod expansion connectors, plus an expansion connector for a camera module, and STLink-V3E embedded debugger.

Availability and pricing

STM32U5 MCUs are sampling now, but only to “lead customers”, and full production is expected for September 2021. Pricing starts at $3.60. The STM32U5 IoT Discovery Kit will be available for order later this year, but the price has not been announced yet. You’ll find additional details in the press release, and product pages for the microcontroller family and development board.

Jean-Luc Aufranc (CNXSoft)

Jean-Luc started CNX Software in 2010 as a part-time endeavor, before quitting his job as a software engineering manager, and starting to write daily news, and reviews full time later in 2011.