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STM32F4 HSE clock frequency without HSE

Question asked by Vasileios Amoiridis on Apr 12, 2018
Latest reply on Apr 24, 2018 by Khouloud G

I am using an STM32F446ZE Nucleo Board which does NOT have an external HSE clock. From CubeMX I set the clock input from the HSE and after in the clock configuration I set the system clock to 180MHz. enter image description here

and in the clock configuration I set the PLL like this enter image description here

The code generated by CubeMX seems to be correct also.enter image description hereMy point is that even if I don't have an HSE in the board the uController works in 180MHz. How is this possible? What is the clock input after all?