Please check: https://community.st.com/s/question/0D53W00000UBHwvSAH/timers-interrupts-not-working-stm32f401re
The problem seems that "HAL_TIM_PeriodElapsedCallback" in "stm32f4xx_hal_tim.c" is not choosing the one function that I wrote in "main.c" under "/* USER CODE BEGIN 4 * "but "__weak void HAL_TIM_PeriodElapsedCallback(TIM_HandleTypeDef *htim)" in that very same file (stm32f4xx_hal_tim.c)
