How to enable Flash Instruction prefetch for a STM32H562 in CubeMX?

[MMeie.3]

Hi

For other STM32 (I checked a STM32L452 and STM32F469) I could enable the Flash Instruction prefetch by setting “Prefetch Buffer” to “Enabled” in the RCC settings. This then set PREFETCH_ENABLE to 1 in stm32F4xx_hal_conf.h.

The STM32H562 also as a Prefetch Buffer, but I cannot find the “Prefetch Buffer” option in CubeMX , and PREFETCH_ENABLE is always 0. Was the “Prefetch Buffer” moved or is it missing?

As a work around I can manually call __HAL_FLASH_PREFETCH_BUFFER_ENABLE(), but having the option back would still be nice.

I use STM32CubeMX Version 6.14 with the Firmware Package V1.5.0 to generate a STM32CubeIDE project on Windows 11.

[mƎALLEm]

Hello,

I'm escalating this internally and I will get back to you with any feedback (internal ticket 207309 not accessible by community members).

Thank you for your patience.

[mƎALLEm]

Hello @MMeie.3 ,

The Prefetch enable buffer option is indeed missing in STM32CubeMx. It will be fixed in the coming revisions of the tool.

Thank you for your contribution. 

[Nemui Trinomius]

Dear ST-Staff,

I didn't notice existence of PrefetchBuffer on STM32H5 until this topic.

I updated my NUCLEO-H563ZI example project with PrefetchBuffer enable.

Here is piece of a sample,I put PrefetchBuffer enable routine after SysClock ramp-uped.

/**************************************************************************/
/*!
    @brief	Configures Main system clocks & power.
	@brief  System Clock Configuration
          The system Clock is configured as follows :
             System Clock source            = PLL (HSE:8MHz)
             SYSCLK(Hz)                     = 250000000
             HCLK(Hz)                       = 250000000
             AHB Prescaler                  = 1
             APB1 Prescaler                 = 1
             APB2 Prescaler                 = 1
             PLL_M                          = 4
             PLL_N                          = 250
             PLL_P                          = 2
             PLL_Q                          = 5
             PLL_R                          = 2
			 PLL_FRACN                      = 0
             Flash Latency(WS)              = 5
	@param  None
	@retval None
*/
/**************************************************************************/
static void SystemClock_Config(void)
{
	RCC_OscInitTypeDef RCC_OscInitStruct = {0};
	RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};
	
	/** Configure the main internal regulator output voltage
	*/
	__HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE0);
	
	while(!__HAL_PWR_GET_FLAG(PWR_FLAG_VOSRDY)) {}
	
	/** Initializes the RCC Oscillators according to the specified parameters
	* in the RCC_OscInitTypeDef structure.
	*/
	RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSE;
	RCC_OscInitStruct.HSEState = RCC_HSE_BYPASS_DIGITAL;
	RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
	RCC_OscInitStruct.PLL.PLLSource = RCC_PLL1_SOURCE_HSE;
	RCC_OscInitStruct.PLL.PLLM = 4;		/* HSE:8MHz/4 = 2MHz */
	RCC_OscInitStruct.PLL.PLLN = 250;	/* 2MHz*250 = 500MHz */
	RCC_OscInitStruct.PLL.PLLP = 2;		/* 500MHz/2 = 250MHz */
	RCC_OscInitStruct.PLL.PLLQ = 5;		/* 500MHz/5 = 100MHz (for SDMMC/SPI) */
	RCC_OscInitStruct.PLL.PLLR = 2;		/* 500MHz/2 = 250MHz */
	RCC_OscInitStruct.PLL.PLLRGE = RCC_PLL1_VCIRANGE_1;
	RCC_OscInitStruct.PLL.PLLVCOSEL = RCC_PLL1_VCORANGE_WIDE;
	RCC_OscInitStruct.PLL.PLLFRACN = 0;
	if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
	{
		for(;;){
			__NOP();
		}
	}
	
	/** Initializes the CPU, AHB and APB buses clocks
	*/
	RCC_ClkInitStruct.ClockType 	 = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
								      |RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2
								      |RCC_CLOCKTYPE_PCLK3;
	RCC_ClkInitStruct.SYSCLKSource 	 = RCC_SYSCLKSOURCE_PLLCLK;
	RCC_ClkInitStruct.AHBCLKDivider  = RCC_SYSCLK_DIV1;	/* SYSCLOCK :250MHz */
	RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV1;	/* PCLK1    :250MHz */
	RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;	/* PCLK2    :250MHz */
	RCC_ClkInitStruct.APB3CLKDivider = RCC_HCLK_DIV1;	/* PCLK3    :250MHz */
	
	if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_5) != HAL_OK)
	{
		for(;;){
			__NOP();
		}
	}
	
	/* If Latency is at least one wait state,then set prefetch buffer enable to improve performance! */
    if (__HAL_FLASH_GET_LATENCY() != FLASH_ACR_LATENCY_0WS)
    {
		if(!(FLASH->ACR & FLASH_ACR_PRFTEN)) {
			__HAL_FLASH_PREFETCH_BUFFER_ENABLE();
		}
    }
	
	/* I/O Compensation for fast interface(OCTO-SPI,SDMMC,SPI,SAI). */
	/* Activate CSI clock mandatory for I/O Compensation Cell*/
	__HAL_RCC_CSI_ENABLE() ;
	/* Enable SBS clock mandatory for I/O Compensation Cell */
	__HAL_RCC_SBS_CLK_ENABLE() ;
	/* Enables the I/O Compensation Cell */
	HAL_SBS_EnableVddIO1CompensationCell();
	HAL_SBS_EnableVddIO2CompensationCell();
}

View more

Entire my project for NUCLEO-H563ZI is here.

To be honest, thanks to strong I-Cache,
the PrefetchBuffer enabled effect is not felt so much(THIS IS A INDIVIDUALLY THOUGHT).
Anyway,works stable for week.I like H5.
I'll research more detail and report on my blog in the future.

Best regards,
Nemui.