Hello,You have to set the prescaler to 108 Mhz to get 1MHz (not 216 Mhz). Keep HCLK to 216 Mhz.Indeed Timer14 is plugged on the output « APB1 timer clock »  that produces 108Mhz,as you can see in STM32CubeMX > clock configuration,  whereas « APB2 tim...