A real time clock, or RTC, is a self-contained timing and clocking generator. It can capture events in real time or be programmed through the I²C port to set timing intervals or to initiate functions. An RTC will always have a built-in oscillator. Adaptations to the standard RTC include a built in 32.768kHz tuning fork watch crystal, a temperature compensated oscillator, or the opportunity to use an external 32.768kHz tuning fork watch crystal. The ASIC microcontroller will feature a built-in I²C communication interface and internal clock registers.