PM0223 datasheet(107/110 Pages) STMICROELECTRONICS

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DocID025763 Rev 1

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PM0223

STM32L0 Core Peripherals

108

4.5.9

MPU design hints and tips

To avoid unexpected behavior, disable the interrupts before updating the attributes of a

region that the interrupt handlers might access.

When setting up the MPU, and if the MPU has previously been programmed, disable

unused regions to prevent any previous region settings from affecting the new MPU setup.

MPU configuration for a microcontroller

Usually, a microcontroller system has only a single processor and no caches. In such a

system, program the MPU as follows:

In most microcontroller implementations, the shareability and cache policy attributes do not

affect the system behavior. However, using these settings for the MPU regions can make

the application code more portable. The values given are for typical situations. In special

systems, such as multiprocessor designs or designs with a separate DMA engine, the

shareability attribute might be important. In these cases refer to the recommendations of the

memory device manufacturer.

Table 39. Memory region attributes for a microcontroller

Memory region

Memory type and attributes

Flash memory

Normal memory, Non-shareable, write-through.

Internal SRAM

Normal memory, Shareable, write-through.

External SRAM

Normal memory, Shareable, write-back, write-allocate.

Peripherals

Device memory, Shareable.

PM0223 データシート(PDF) 107 Page - STMicroelectronics