Associate III
February 5, 2021
Question
Stange performance comparison between STM32F427 and STM32H745
- February 5, 2021
- 3 replies
- 2692 views
Hi everyone,
I recently revamped a product with a STM32F427 with a new STM32H745.
Both cards have an external RAM of 16Mbyte. In the STM32F4 the data bus is 16bit width while in the SRM32H7 the data but is 32bit width.
Both cards are set to go to the maximum speed @168MHz for the STM32F4 to 480MHz for the STM32H7.
I noticed that with simple memory access operations such as (memcpy, arm_copy_q31, memset and arm_fill_q31) I obtained very different values and that do not return with the performance that I would have expected. (see attached file). In particular it seems that STM32F4 is faster than the other STM32H7 despite having a much lower clock.
Also I don't explain why, the operations performed on SRAM_D1 and DTC_RAM have comparable execution times even if on DTC_RAM should be much faster.
Here is a few code used to check performance:
startTimeTest=HAL_GetTime_us();
memcpy(DestIntTest,SourceIntTest,50000*sizeof(uint8_t));
Timetest1=HAL_GetTime_us()-startTimeTest;
startTimeTest=HAL_GetTime_us();
arm_copy_q31((q31_t *)SourceIntTest, (q31_t *)DestIntTest, 12500);
Timetest2=HAL_GetTime_us()-startTimeTest;
startTimeTest=HAL_GetTime_us();
memcpy(DestExtTest,SourceExtTest,1000000*sizeof(uint8_t));
Timetest3=HAL_GetTime_us()-startTimeTest;
startTimeTest=HAL_GetTime_us();
arm_copy_q31((q31_t *)SourceExtTest, (q31_t *)DestExtTest, 250000);
Timetest4=HAL_GetTime_us()-startTimeTest;And here the clock setup on STM32H7:
void SystemClock_Config_HSE(void)
{
RCC_OscInitTypeDef RCC_OscInitStruct = {0};
RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};
RCC_PeriphCLKInitTypeDef PeriphClkInitStruct = {0};
/** Supply configuration update enable
*/
HAL_PWREx_ConfigSupply(PWR_LDO_SUPPLY);
/** 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_ON;
RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;
RCC_OscInitStruct.PLL.PLLM = 5;
RCC_OscInitStruct.PLL.PLLN = 192;
RCC_OscInitStruct.PLL.PLLP = 2;
RCC_OscInitStruct.PLL.PLLQ = 2;
RCC_OscInitStruct.PLL.PLLR = 2;
RCC_OscInitStruct.PLL.PLLRGE = RCC_PLL1VCIRANGE_2;
RCC_OscInitStruct.PLL.PLLVCOSEL = RCC_PLL1VCOWIDE;
RCC_OscInitStruct.PLL.PLLFRACN = 4096;
if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
{
while(1) { ; }//>> Error_Handler();
}
/** 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_D3PCLK1|RCC_CLOCKTYPE_D1PCLK1;
RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
RCC_ClkInitStruct.SYSCLKDivider = RCC_SYSCLK_DIV1;
RCC_ClkInitStruct.AHBCLKDivider = RCC_HCLK_DIV2;
RCC_ClkInitStruct.APB3CLKDivider = RCC_APB3_DIV1;
RCC_ClkInitStruct.APB1CLKDivider = RCC_APB1_DIV1;
RCC_ClkInitStruct.APB2CLKDivider = RCC_APB2_DIV1;
RCC_ClkInitStruct.APB4CLKDivider = RCC_APB4_DIV1;
if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_4) != HAL_OK)
{
while(1) { ; }//>> Error_Handler();
}
/* HSI48 for USB Clock */
PeriphClkInitStruct.PeriphClockSelection = RCC_PERIPHCLK_USB;
PeriphClkInitStruct.UsbClockSelection = RCC_USBCLKSOURCE_HSI48;
if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInitStruct) != HAL_OK)
{
while(1) { ; }
}
/* Set the ADC peripheral clock*/
PeriphClkInitStruct.PeriphClockSelection = RCC_PERIPHCLK_ADC;
PeriphClkInitStruct.PLL2.PLL2M = 1;
PeriphClkInitStruct.PLL2.PLL2N = 18;
PeriphClkInitStruct.PLL2.PLL2P = 1;
PeriphClkInitStruct.PLL2.PLL2Q = 2;
PeriphClkInitStruct.PLL2.PLL2R = 2;
PeriphClkInitStruct.PLL2.PLL2RGE = RCC_PLL2VCIRANGE_3;
PeriphClkInitStruct.PLL2.PLL2VCOSEL = RCC_PLL2VCOMEDIUM;
PeriphClkInitStruct.PLL2.PLL2FRACN = 6144;
PeriphClkInitStruct.AdcClockSelection = RCC_ADCCLKSOURCE_PLL2;
if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInitStruct) != HAL_OK)
{
while(1) { ; }
}
PeriphClkInitStruct.PeriphClockSelection = RCC_PERIPHCLK_SPI5|RCC_PERIPHCLK_SPI4;
PeriphClkInitStruct.Spi45ClockSelection = RCC_SPI45CLKSOURCE_D2PCLK1;
if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInitStruct) != HAL_OK)
{
while(1) { ; }
}
PeriphClkInitStruct.PeriphClockSelection = RCC_PERIPHCLK_UART4;
PeriphClkInitStruct.Usart234578ClockSelection = RCC_USART234578CLKSOURCE_D2PCLK1;
if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInitStruct) != HAL_OK)
{
while(1) { ; }
}
PeriphClkInitStruct.PeriphClockSelection = RCC_PERIPHCLK_I2C4;
PeriphClkInitStruct.I2c4ClockSelection = RCC_I2C4CLKSOURCE_D3PCLK1;
if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInitStruct) != HAL_OK)
{
while(1) { ; }
}
/* Enable SYSCFG clock mondatory for I/O Compensation Cell */
__HAL_RCC_SYSCFG_CLK_ENABLE() ;
/* Enables the I/O Compensation Cell */
HAL_EnableCompensationCell();
/** Enables the Clock Security System
*/
HAL_RCC_EnableCSS();
}Any help will be appreciated.
thanks in advance,
DM