STM32H563 clock at 250Mhz

[dvescovi]

I was trying to get the most out of my H563 set up and run as fast as possible.

I am using the Nucleo-H563 board.

I reconfigured in CubeMX to use System clock mux to use HSE source mux, multipliers and dividers set correctly for 250MHZ operation. There are no errors shown in the setup and I am showing 250 Mhz as the SYSCLK. My AHB is /1, HCLK shows 250MHZ which is feeding the peripheral busses.

While the clock configuration APB1 shows 250Mhz it does not seem to be correct as when I set the timers and prescalers for such the timing is not correct... the bus seems to be running at 125mhz.

For my TMR1 to get 1us clock I have to set the divider to 124 which implies the internal clock is running at 125Mhz not 250 like the clock diagram shows. 

I have attached the Clock Configuration from CubeMX that shows no clock issues.

[AScha.3]

I have a nucleo H563 also running at 250 MHz.

So if you have wrong core frequency, usually wrong HSE clock going to the CPU.

So check the real HSE frequency with a scope.

To check the internal frequency, use the MCO output, set it in Cube and then check with scope.

[TDK]

> For my TMR1 to get 1us clock

Glossing over a lot of details there. How are you assessing the timer has a "1us clock"? Is the CPU involved? How is the timer configured? Toggling a timer pin will appear at half the timer update frequency.