The Real Time Clock (RTC) is a clock-calendar IP core that keeps track of the “Time of Day”. The core is organized as a series of BCD counters that counts Seconds, Minutes, Hours, Days, Months and Years (Time Units).
The RTC seconds counter time base is generated from a clock input that is separate from the system clock. The time-base for the seconds counter is nominally 32.768 kHz. To aid in precision, there is programmable terminal count (divisor) for this clock. Calibration accuracy is controlled by software.