Solved
HAL_RCC_GetSysClockFrequency() gives wrong value for input clock
I am using stm32f767zi nucleo board and they HSE clock input is coming from st link debugger which according to data sheet of the board generates an 8 MHz MCO signal which is fed into the OSC_in pin. I have configured HSE bypass as the clk source for my mcu and configured the SYSCLK to be 8 MHZ(same as HSE). there is no PLL. However when I try to call the above method to see the current sysclk freq, the degugger shows it as 25 MHz which is clearly wrong.
my code for configuring clock is shown below.
void SystemClockConfig()
{
RCC_OscInitTypeDef osc_init;
osc_init.OscillatorType = RCC_OSCILLATORTYPE_HSE;
// after reset HSE is off, so you have to give it a new state
osc_init.HSEState = RCC_HSE_BYPASS;
osc_init.PLL.PLLState = RCC_PLL_NONE;
if (HAL_RCC_OscConfig(&osc_init) != HAL_OK)
{
// there is somethign wrong in initialization
Error_handler();
}
//
//
RCC_ClkInitTypeDef clk_init;
clk_init.ClockType = RCC_CLOCKTYPE_HCLK | RCC_CLOCKTYPE_SYSCLK | RCC_CLOCKTYPE_PCLK1 | RCC_CLOCKTYPE_PCLK2 ;
// next we will enable HSE as the clock source.
clk_init.SYSCLKSource = RCC_SYSCLKSOURCE_HSE;
// next we will set AHB prescaler to get HWCLK of 4 MHz
clk_init.AHBCLKDivider = RCC_SYSCLK_DIV2;
clk_init.APB1CLKDivider = RCC_HCLK_DIV2; // to set APB1 clock as 2 MHz
clk_init.APB2CLKDivider = RCC_HCLK_DIV2;
if (HAL_RCC_ClockConfig(&clk_init, FLASH_ACR_LATENCY_0WS) != HAL_OK)
{
Error_handler();
}
__HAL_RCC_HSI_DISABLE();
__HAL_RCC_PLL_DISABLE();
HAL_SYSTICK_Config(4000);
HAL_SYSTICK_CLKSourceConfig(SYSTICK_CLKSOURCE_HCLK);
}However when i monitor the value of uint32_t SYSCLK = HAL_RCC_GetSysClockFreq(); this shows 25 MHz. the image is shown below.
What could be the issue here
