Why is RCC_FLAG_CPURST disabled by a #ifdef in the stm32h7xx_hal_rcc.h?

[PAHA]

In the HAL Library for the STM32H7 familiy (version 1.11.0) downloaded with STMCubeMx there is the following entry in the stm32h7xx_hal_rcc.h file:

#if defined(RCC_RSR_CPURSTF)           // <<---- This is the line in question
#define RCC_FLAG_CPURST                ((uint8_t)0x91)
#endif /* RCC_RSR_CPURSTF */
 [...]
 
#define RCC_FLAG_C1RST                 (RCC_FLAG_CPURST)
#define RCC_FLAG_C2RST                 ((uint8_t)0x92)

In the stm32h755xx.h file the "RCC_RSR_CPURSTF" is not defined. Why is that?

According to the reference manual (RM0399, chapter 9.7.38) there is C1RSTF flag in the RCC_RSR register at bit position 17, which corresponds to the defined value above of 0x91 for RCC_FLAG_C1RST (if it was active) when using the Makro "__HAL_RCC_GET_FLAG(...)" to check wheter a C1RST occurred.

The above mentioned "#if defined(RCC_RSR_CPURSTF)   " was introduced after HAL Library version 1.5.0, where there was no such define.

When we are looking for example in the "stm32h753xx.h" device file, there this define is present:

#define RCC_RSR_CPURSTF_Pos                    (17U)
#define RCC_RSR_CPURSTF_Msk                    (0x1UL << RCC_RSR_CPURSTF_Pos)  /*!< 0x00020000 */
#define RCC_RSR_CPURSTF                        RCC_RSR_CPURSTF_Msk

When we are looking in the "stm32h755xx.h" (which we are using) device file, the define appears but it is renamed:

#define RCC_RSR_C1RSTF_Pos                     (17U)
#define RCC_RSR_C1RSTF_Msk                     (0x1UL << RCC_RSR_C1RSTF_Pos)   /*!< 0x00020000 */
#define RCC_RSR_C1RSTF                         RCC_RSR_C1RSTF_Msk

However, in the stm32h7xx_hal_rcc.h the #ifdef is still done for "RCC_RSR_CPURSTF" (see above).

Is this renaming of this flag an error in the HAL library for the STM32H755?

With the actual HAL library it is not possible to check if a C1RST occurred or not.

Any help is appreciated.

[Pavel A.]

H753 is a single-core H7. The system reset internals in single and dual core H7's may differ.

[PAHA]

Yes I know that they may differ.

My point with the H753 was that "RCC_RSR_CPURSTF" is defined but the same information is named "RCC_RSR_C1RSTF" on the H755. However, in the stme32h7xx_hal_rcc.h the #ifdef is only performed on the "RCC_RSR_CPURSTF".

So the information

#define RCC_FLAG_CPURST                ((uint8_t)0x91)

is not available for the H755 but it should be. Also the number (0x91) is correct for the H755.

Therefore my question, how do I check if a CR1RST reset cause happend for a H755 with the HAL library, without manually manipulating the library?

[Tesla DeLorean]

This. The two cores have their own reset signals.

And be aware there have been multiple die stepping over several years of development, with added or resolved functionality.

The errata might be instructive. ​

[PAHA]

The two respective reset signals are

#define RCC_FLAG_C1RST                 (RCC_FLAG_CPURST)
#define RCC_FLAG_C2RST                 ((uint8_t)0x92)

Where RCC_FLAG_C1RST corresponds to RCC_FLAG_CPURST which should correspond to 0x91. However, the latter is not defined (falsly?) for the H755.