STM32H750IB getting into persistent problem with SCB_EnableDCache

Hi, and thanks for the response.  I don't think it' the Y revision, at least none of the letters on the part number were a 'Y', how do we know for sure?

Regarding the 'speculative execution' workaround, specifically how do I do it?  I'll give it a try.

Thanks for your response, and yes, the schematic isn't very helpful,  though I think it's a pretty standard design.

The strangest aspect of this issue is that it's working fine for most boards and most people most of the time.  It happened to me once on one board, and then after doing a Chip Erase, it went back to a 'working' state, and now it randomly started happening on another board and I haven't been able to get it back by chip erase, etc.  So that's the most puzzling part.  This board has been out for several years now, so it's obviously not a very common problem, though several other people have reported it.

In terms of the code, it's the Blink example from the DaisyExamples:  https://github.com/electro-smith/libDaisy

Here's the memory initialization code:  (libDaisy\src\sys\system.cpp)

void System::ConfigureMpu()
{
 MPU_Region_InitTypeDef MPU_InitStruct;
 HAL_MPU_Disable();
 // Configure RAM D2 (SRAM1) as non cacheable
 MPU_InitStruct.Enable = MPU_REGION_ENABLE;
 MPU_InitStruct.BaseAddress = 0x30000000;
 MPU_InitStruct.Size = MPU_REGION_SIZE_32KB;
 MPU_InitStruct.AccessPermission = MPU_REGION_FULL_ACCESS;
 MPU_InitStruct.IsBufferable = MPU_ACCESS_NOT_BUFFERABLE;
 MPU_InitStruct.IsCacheable = MPU_ACCESS_NOT_CACHEABLE;
 MPU_InitStruct.IsShareable = MPU_ACCESS_SHAREABLE;
 MPU_InitStruct.Number = MPU_REGION_NUMBER0;
 MPU_InitStruct.TypeExtField = MPU_TEX_LEVEL1;
 MPU_InitStruct.SubRegionDisable = 0x00;
 MPU_InitStruct.DisableExec = MPU_INSTRUCTION_ACCESS_ENABLE;
 HAL_MPU_ConfigRegion(&MPU_InitStruct);

 MPU_InitStruct.IsCacheable = MPU_ACCESS_CACHEABLE;
 MPU_InitStruct.IsBufferable = MPU_ACCESS_BUFFERABLE;
 MPU_InitStruct.IsShareable = MPU_ACCESS_NOT_SHAREABLE;
 MPU_InitStruct.Number = MPU_REGION_NUMBER1;
 MPU_InitStruct.TypeExtField = MPU_TEX_LEVEL0;
 MPU_InitStruct.Size = MPU_REGION_SIZE_64MB;
 MPU_InitStruct.BaseAddress = 0xC0000000;
 HAL_MPU_ConfigRegion(&MPU_InitStruct);

 // Configure the backup SRAM region as non-cacheable
 MPU_InitStruct.IsCacheable = MPU_ACCESS_NOT_CACHEABLE;
 MPU_InitStruct.IsBufferable = MPU_ACCESS_NOT_BUFFERABLE;
 MPU_InitStruct.IsShareable = MPU_ACCESS_SHAREABLE;
 MPU_InitStruct.Number = MPU_REGION_NUMBER2;
 MPU_InitStruct.TypeExtField = MPU_TEX_LEVEL1;
 MPU_InitStruct.Size = MPU_REGION_SIZE_4KB;
 MPU_InitStruct.BaseAddress = 0x38800000;
 HAL_MPU_ConfigRegion(&MPU_InitStruct);

 HAL_MPU_Enable(MPU_PRIVILEGED_DEFAULT);
}

And here's the overall init function: (libDaisy\src\sys\system.cpp)

As far as I can tell, it's doing the 'if (!config.skip_clocks)' code.

void System::Init(const System::Config& config)
{
 cfg_ = config;
 HAL_Init();
 if(!config.skip_clocks)
 {
 ConfigureClocks();
 ConfigureMpu();
 }
 dsy_dma_init();
 dsy_i2c_global_init();
 dsy_spi_global_init();
 dsy_uart_global_init();

 // Initialize Caches
 if(config.use_dcache)
 SCB_EnableDCache();
 if(config.use_icache)
 SCB_EnableICache();

 // Configure and start highspeed timer.
 // TIM 2 counter UP (defaults to fastest tick/longest period).
 TimerHandle::Config timcfg;
 timcfg.periph = TimerHandle::Config::Peripheral::TIM_2;
 timcfg.dir = TimerHandle::Config::CounterDir::UP;
 tim_.Init(timcfg);
 tim_.Start();

 // Initialize the true random number generator
 Random::Init();
}