is there any good documentation on tim1 and tim8 (advanced timers). The info in the reference manual is useless.

[Tesla DeLorean]

The TIM are relatively ugly, but not sure the documentation is wrong, just a bit intractable.

https://www.st.com/resource/en/application_note/an4776-generalpurpose-timer-cookbook-for-stm32-microcontrollers-stmicroelectronics.pdf

https://www.st.com/resource/en/application_note/an4013-stm32-crossseries-timer-overview-stmicroelectronics.pdf

https://deepbluembedded.com/stm32-timers-tutorial-hardware-timers-explained/