STM32L471XX Datasheet, PDF (16/218 Pages) STMicroelectronics – Batch acquisition mode

Functional overview
3
Functional overview
STM32L471xx
3.1
ARM^® Cortex^®-M4 core with FPU
The ARM^® Cortex^®-M4 with FPU processor is the latest generation of ARM processors for
embedded systems. It was developed to provide a low-cost platform that meets the needs of
MCU implementation, with a reduced pin count and low-power consumption, while
delivering outstanding computational performance and an advanced response to interrupts.
The ARM^® Cortex^®-M4 with FPU 32-bit RISC processor features exceptional code-
efficiency, delivering the high-performance expected from an ARM core in the memory size
usually associated with 8- and 16-bit devices.
The processor supports a set of DSP instructions which allow efficient signal processing and
complex algorithm execution.
Its single precision FPU speeds up software development by using metalanguage
development tools, while avoiding saturation.
With its embedded ARM core, the STM32L471xx family is compatible with all ARM tools
and software.
Figure 1 shows the general block diagram of the STM32L471xx family devices.
3.2
Adaptive real-time memory accelerator (ART Accelerator™)
The ART Accelerator™ is a memory accelerator which is optimized for STM32 industry-
standard ARM^® Cortex^®-M4 processors. It balances the inherent performance advantage of
the ARM^® Cortex^®-M4 over Flash memory technologies, which normally requires the
processor to wait for the Flash memory at higher frequencies.
To release the processor near 100 DMIPS performance at 80MHz, the accelerator
implements an instruction prefetch queue and branch cache, which increases program
execution speed from the 64-bit Flash memory. Based on CoreMark benchmark, the
performance achieved thanks to the ART accelerator is equivalent to 0 wait state program
execution from Flash memory at a CPU frequency up to 80 MHz.
3.3
Memory protection unit
The memory protection unit (MPU) is used to manage the CPU accesses to memory to
prevent one task to accidentally corrupt the memory or resources used by any other active
task. This memory area is organized into up to 8 protected areas that can in turn be divided
up into 8 subareas. The protection area sizes are between 32 bytes and the whole 4
gigabytes of addressable memory.
The MPU is especially helpful for applications where some critical or certified code has to be
protected against the misbehavior of other tasks. It is usually managed by an RTOS (real-
time operating system). If a program accesses a memory location that is prohibited by the
MPU, the RTOS can detect it and take action. In an RTOS environment, the kernel can
dynamically update the MPU area setting, based on the process to be executed.
The MPU is optional and can be bypassed for applications that do not need it.
16/218
DocID027226 Rev 1