The RTCC can keep a running clock of the current date and time, it also has an alarm feature that can be used to wake the microcontroller from Deep Sleep at a specified date/time. Unlike the DSWT, granularity is not restricted to 16 options; any date/time can be used. The internal low-power RC oscillator or the secondary oscillator can be used for a clock source, just like the DSWT. If both the RTCC and DSWT are going to be used, and robustness is not a key concern, the same clock source can be used so that power isn’t wasted keeping two oscillator circuits running. During Deep Sleep, I/O pins are generally held constant in their last configured state. However, the RTCC can be configured to output an alarm pulse or seconds clock output on the RTCC pin, even while the microcontroller is in Deep Sleep. This pulse could be used to continuously blink an indicator on a clock read out, for example.