Hi
I found the answer to the overwriting problem. The two areas which were overwriting the ITCM ram were the Octo Spi Initialization function for the discovery board STM32H7B3I-DK and the uxListRemove of FreeRTOS.
The first of these was:
static void MX_OCTOSPI1_Init(void)
{
/* USER CODE END OCTOSPI1_Init 1 */
/* OCTOSPI1 parameter configuration*/
hospi1.Instance = OCTOSPI1;
hospi1.Init.FifoThreshold = 1;
hospi1.Init.DualQuad = HAL_OSPI_DUALQUAD_DISABLE;
...
hospi1.Init.MaxTran = 0;
hospi1.Init.Refresh = 0;
if (HAL_OSPI_Init(&hospi1) != HAL_OK)
{
Error_Handler();
}
/* USER CODE BEGIN OCTOSPI1_Init 2 */
BSP_OSPI_NOR_Init_t Flash;
Flash.InterfaceMode = BSP_OSPI_NOR_OPI_MODE;
Flash.TransferRate = BSP_OSPI_NOR_DTR_TRANSFER;
hospi_nor->Instance = hospi1.Instance; /* rjg mod */
BSP_OSPI_NOR_DeInit(0);
int32_t RetVal = BSP_OSPI_NOR_Init(0, &Flash);
if(RetVal != BSP_ERROR_NONE)
{
Error_Handler();
}
RetVal = BSP_OSPI_NOR_EnableMemoryMappedMode(0);
if(RetVal != BSP_ERROR_NONE)
{
Error_Handler();
}
/* USER CODE END OCTOSPI1_Init 2 */
}
The programmer creates a new handle for the ospi driver called hospi_nor, but doesn't initialize it to the hardware instance of the actual peripherals memory locations. The sequence is:
BSP_OSPI_NOR_DeInit(uint32_t Instance) below calls
if (HAL_OSPI_DeInit(&hospi_nor[Instance]) != HAL_OK). Line 34.
/**
* @brief De-Initializes the OSPI interface.
* @param Instance OSPI Instance
* @retval BSP status
*/
int32_t BSP_OSPI_NOR_DeInit(uint32_t Instance)
{
int32_t ret = BSP_ERROR_NONE;
/* Check if the instance is supported */
if(Instance >= OSPI_NOR_INSTANCES_NUMBER)
{
ret = BSP_ERROR_WRONG_PARAM;
}
else
{
/* Disable Memory mapped mode */
if(Ospi_Nor_Ctx[Instance].IsInitialized == OSPI_ACCESS_MMP)
{
if(BSP_OSPI_NOR_DisableMemoryMappedMode(Instance) != BSP_ERROR_NONE)
{
ret = BSP_ERROR_COMPONENT_FAILURE;
}
}
if(ret == BSP_ERROR_NONE)
{
/* Set default Ospi_Nor_Ctx values */
Ospi_Nor_Ctx[Instance].IsInitialized = OSPI_ACCESS_NONE;
Ospi_Nor_Ctx[Instance].InterfaceMode = BSP_OSPI_NOR_SPI_MODE;
Ospi_Nor_Ctx[Instance].TransferRate = BSP_OSPI_NOR_STR_TRANSFER;
#if (USE_HAL_OSPI_REGISTER_CALLBACKS == 0)
OSPI_NOR_MspDeInit(&hospi_nor[Instance]);
#endif /* (USE_HAL_OSPI_REGISTER_CALLBACKS == 0) */
/* Call the DeInit function to reset the driver */
if (HAL_OSPI_DeInit(&hospi_nor[Instance]) != HAL_OK)
{
ret = BSP_ERROR_PERIPH_FAILURE;
}
}
}
/* Return BSP status */
return ret;
}
if (HAL_OSPI_DeInit(&hospi_nor[Instance]) != HAL_OK) this calls macro
CLEAR_BIT(hospi->Instance->DCR1, OCTOSPI_DCR1_FRCK); Line 17 below.
HAL_StatusTypeDef HAL_OSPI_DeInit(OSPI_HandleTypeDef *hospi)
{
HAL_StatusTypeDef status = HAL_OK;
/* Check the OSPI handle allocation */
if (hospi == NULL)
{
status = HAL_ERROR;
/* No error code can be set set as the handler is null */
}
else
{
/* Disable OctoSPI */
__HAL_OSPI_DISABLE(hospi);
/* Disable free running clock if needed : must be done after OSPI disable */
CLEAR_BIT(hospi->Instance->DCR1, OCTOSPI_DCR1_FRCK);
as hospi_nor isn't initialized the clear bit macro accesses the ITCM address at offset #4.
I don't know what the programmer was trying to achieve and I didn't want to break working? code so I added the line:
hospi_nor->Instance = hospi1.Instance; /* rjg mod */
This sets the hospi_nor.Instance to the correct peripheral address.
The second area overwriting was the uxListRemove function of the FreeRTOS lists module.
UBaseType_t uxListRemove( ListItem_t * const pxItemToRemove )
{
/* The list item knows which list it is in. Obtain the list from the list
item. */
List_t * const pxList = pxItemToRemove->pxContainer;
pxItemToRemove->pxNext->pxPrevious = pxItemToRemove->pxPrevious;
pxItemToRemove->pxPrevious->pxNext = pxItemToRemove->pxNext;
...
}
Lines 7 and 8 were the lead in the saddlebags here. The cause was twofold first I had executed a task suspend before starting the scheduler and secondly i used taskSuspend on a sw timer rather than timerStop. This causes the uxTaskRemove function to behave badly and corrupt the ITCM.
Fixing my two errors stopped the problem, but I could see the same thing happening again. To prevent writing to the ITCM ram program area I invoked the MPU after copying the code from flash to ram. I set the MPU for this ram to read only so if I inadvertently try to write to it I will get a memory fault which is a lot safer than if the program soldiers on with bad code in the ITCM.
It was all worth it as my critical functions with compiler optimization on only take 190 us compared to 500 us before.
Just to help others my startup code and linker script are attached.
and my function calls are:
__attribute__((section(".Tim2itcm"))) void PositionFilter_step(void)
{
...
}
__attribute__((section(".Tim2itcm"))) void impulseCurveFit_step(void)
{
...
}
etc.
Anyway guys thanks for your help.
Best regards
Rob
