STM32F7 Clock unable to reach 216 MHz
Hi,
I'm facing an issue with a new project I'm working on, I just received a custom board based on a STM32F746VGT6 MCU, the MCU wasn't able to run my base program, (generated via MXCube), so I started changing parameters to find the source, and it led me to this : when I bring the clock speed down my program run without problems. But when I run with frequencies above ~120MHz, then the program stop working. For now my program just toggle 2 GPIOs : one in the systick handler and the other in a timer interrupt.
At first I thought it could be a problem between openocd and the board, but even without the debugger the program wont run above 140MHz. I'm using a 8MHz crystal oscillator as clock source, below is the source code of the
SystemClock_Config() function from my program. When I bring
RCC_OscInitStruct.PLL.PLLN below ~ 240 my program runs. But when I go up in frequencies my program goes in Hardfault at random places.
void SystemClock_Config(void)
{
RCC_OscInitTypeDef RCC_OscInitStruct;
RCC_ClkInitTypeDef RCC_ClkInitStruct;
RCC_PeriphCLKInitTypeDef PeriphClkInitStruct;
/**Configure the main internal regulator output voltage */
__HAL_RCC_PWR_CLK_ENABLE();
__HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE1);
/**Initializes the CPU, AHB and APB busses clocks */
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 = 8;
RCC_OscInitStruct.PLL.PLLN = 432;
RCC_OscInitStruct.PLL.PLLP = RCC_PLLP_DIV2;
RCC_OscInitStruct.PLL.PLLQ = 9;
if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
{
Error_Handler();
}
/**Activate the Over-Drive mode */
if (HAL_PWREx_EnableOverDrive() != HAL_OK)
{
Error_Handler();
}
/**Initializes the CPU, AHB and APB busses clocks */
RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
|RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2;
RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV4;
RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV2;
if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_7) != HAL_OK)
{
Error_Handler();
}
PeriphClkInitStruct.PeriphClockSelection = RCC_PERIPHCLK_USART2|RCC_PERIPHCLK_CLK48;
PeriphClkInitStruct.PLLSAI.PLLSAIN = 192;
PeriphClkInitStruct.PLLSAI.PLLSAIR = 2;
PeriphClkInitStruct.PLLSAI.PLLSAIQ = 2;
PeriphClkInitStruct.PLLSAI.PLLSAIP = RCC_PLLSAIP_DIV4;
PeriphClkInitStruct.PLLSAIDivQ = 1;
PeriphClkInitStruct.PLLSAIDivR = RCC_PLLSAIDIVR_2;
PeriphClkInitStruct.Usart2ClockSelection = RCC_USART2CLKSOURCE_PCLK1;
PeriphClkInitStruct.Clk48ClockSelection = RCC_CLK48SOURCE_PLLSAIP;
if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInitStruct) != HAL_OK)
{
Error_Handler();
}
/**Configure the Systick interrupt time */
HAL_SYSTICK_Config(HAL_RCC_GetHCLKFreq()/1000);
/**Configure the Systick */
HAL_SYSTICK_CLKSourceConfig(SYSTICK_CLKSOURCE_HCLK);
/* SysTick_IRQn interrupt configuration */
HAL_NVIC_SetPriority(SysTick_IRQn, 2, 0);
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Cheers,
Mathieu