Data Structures

General Description

Data Structures
struct	stl_mpu_entry_t
	Entry parameters for SelfTest_MPU(), supplied by the application. More...

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Data Structure Documentation

stl_mpu_entry_t

struct stl_mpu_entry_t

Data Fields
volatile uint32_t *	testAddress	First word of a dedicated MPU_TEST_BLOCK_BYTES block, aligned to MPU_TEST_BLOCK_BYTES, that holds no other data and no stack, for example CY_ALIGN(32) static volatile uint32_t scratch[8];. The whole block is read-only while the test runs; any other write to it (for example from an ISR) raises a MemManage fault that the STL does not consume. Any normal memory (cacheable or non-cacheable) is supported: the ARM core MPU is checked before the D-cache.
uint32_t	expectedValue	Value stl_mpu_entry_t::testAddress must hold before the test runs, for example 0x5A5A5A5A. The application must prime the scratch word with this value before every call to SelfTest_MPU(). If the denied write does not fault, stl_mpu_entry_t::writeValue remains in the scratch word.
uint32_t	writeValue	Value the self-test attempts to write. Must differ from stl_mpu_entry_t::expectedValue.
uint8_t	regionNumber	Spare MPU region index to borrow for the duration of the test, from MPU_TEST_MIN_REGION_NUM to the highest region implemented by the core (MPU->TYPE.DREGION - 1, checked at run time; 15 on XMC7000 CM7). Region 0 is excluded because BSPs for cache-enabled cores (for example XMC7000 CM7) typically reserve it for a non-cacheable memory window. The region must be disabled when SelfTest_MPU() is called, its RBAR and RASR are overwritten and left disabled after the test. When enabled regions overlap, ARMv7-M applies the attributes of the highest-numbered one. A higher-numbered enabled region that allows privileged writes over the scratch block therefore overrides the test region: the write succeeds and SelfTest_MPU() returns ERROR_STATUS, which cannot be differentiated from an MPU defect. Use the highest free region number, or make sure no higher-numbered region overlaps the scratch block.