Inverts the bit in the DM register that is selected by DN. Thus if DN=3 (Thursday) bit 3 of DM will be inverted.
Bits in the Day Mask register are assigned as follows:
| bit | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
| value | 64 | 32 | 16 | 8 | 4 | 2 | 1 | |
| - | Sun | Sat | Fri | Thr | Wed | Tue | Mon |
RTC documentation and tutorial
Dialect exclusions: Not available in dialects before 16.