TIM8 option register 2
| BKINE | BRK BKIN input enable |
| BKCMP1E | BRK COMP1 enable |
| BKCMP2E | BRK COMP2 enable |
| BKDFBK2E | BRK DFSDM_BREAK[2] enable |
| BKINP | BRK BKIN input polarity |
| BKCMP1P | BRK COMP1 input polarity |
| BKCMP2P | BRK COMP2 input polarity |
| ETRSEL | ETR source selection |