STM32 setting AHB clock speed goes into infinite loop in HAL_RCC_ClockConfig
Hey everyone!
I'm trying to decrease the clock speed of TIM3 on my STM32L452RET6 (NUCLEO-L452RE) and i've run into issues. I think i figured it out already but I just don't understand why the problem is. My clock tree looks like this in CubeMX:
With this configuration and the default generated code the SystemClock_Config function looks like this:
void SystemClock_Config(void) {
RCC_OscInitTypeDef RCC_OscInitStruct = { 0 };
RCC_ClkInitTypeDef RCC_ClkInitStruct = { 0 };
/** Configure the main internal regulator output voltage
*/
if (HAL_PWREx_ControlVoltageScaling(PWR_REGULATOR_VOLTAGE_SCALE1) != HAL_OK) Error_Handler();
/** Initializes the RCC Oscillators according to the specified parameters
* in the RCC_OscInitTypeDef structure.
*/
RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI;
RCC_OscInitStruct.HSIState = RCC_HSI_ON;
RCC_OscInitStruct.HSICalibrationValue = 64;
RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSI;
RCC_OscInitStruct.PLL.PLLM = 1;
RCC_OscInitStruct.PLL.PLLN = 8;
RCC_OscInitStruct.PLL.PLLP = RCC_PLLP_DIV7;
RCC_OscInitStruct.PLL.PLLQ = RCC_PLLQ_DIV2;
RCC_OscInitStruct.PLL.PLLR = RCC_PLLR_DIV2;
if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK) 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_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV16;
RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV16;
RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;
if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_0) != HAL_OK) Error_Handler();
}
The problem is that it goes into an infinite loop at HAL_RCC_ClockConfig function. And no, it doesn't reach the Error_Handler function (according to the debugger). And after some digging I've found this table in the RM:
According to this the flash latency is correct, because my HCLK frequency is less than 16MHz. But if I set the flash latency to 1WS (FLASH_LATENCY_1) it starts working again. Does anyone have an explanation of why that is? It a bit annoying because i need to rewrite this every single time a regenerate the code.