alternate function option register 1
| BKINE | BRK BKIN input enable |
| BKCMP1E | BRK COMP1 enable |
| BKCMP2E | BRK COMP2 enable |
| BKCMP3E | tim_brk_cmp3 enable |
| BKCMP4E | tim_brk_cmp4 enable |
| BKCMP5E | tim_brk_cmp5 enable |
| BKCMP6E | tim_brk_cmp6 enable |
| BKCMP7E | tim_brk_cmp7 enable |
| BKCMP8E | tim_brk_cmp8 enable |
| BKINP | TIMx_BKIN input polarity |
| BKCMP1P | BRK COMP1 input polarity |
| BKCMP2P | BRK COMP2 input polarity |
| BKCMP3P | tim_brk_cmp3 input polarity |
| BKCMP4P | tim_brk_cmp4 input polarity |
| ETRSEL | ETR source selection |