HSE is not working on STM32F411E-Discovery

[Duc_Tran]

I’ve just started learning STM32 and I’m currently using the STM32F411E-Discovery board. I loaded the default code provided by the Board Selector in STM32CubeIDE and was trying to get a simple LED blink working. It works fine when using the internal HSI clock, but it doesn’t seem to work when I switch to the external HSE clock. The only different is:
HSI:

RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI;
RCC_OscInitStruct.HSIState = RCC_HSI_ON;
RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSI;
RCC_OscInitStruct.PLL.PLLM = 16;
RCC_OscInitStruct.PLL.PLLN = 336;
RCC_OscInitStruct.PLL.PLLP = RCC_PLLP_DIV4;
RCC_OscInitStruct.PLL.PLLQ = 7;

HSE:

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 = 336;
RCC_OscInitStruct.PLL.PLLP = RCC_PLLP_DIV4;
RCC_OscInitStruct.PLL.PLLQ = 7;

[Andrew Neil]

Welcome to the forum.

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@Duc_Tran wrote:

it doesn’t seem to work when I switch to the external HSE clock.  

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What do you mean by, "doesn’t seem to work"? Please describe the symptoms you see.

Have you used the debugger to see what's happening?

Does that board have a crystal for HSE, or is it clocked  from the ST-Link?

Details should be in the User Manual ...

I've edited you post to apply the proper source code formatting - please see How to insert source code for future reference.

See also: How to write your question to maximize your chances to find a solution.