Real time clock of LPC2148
LPC2000 series of microcontrollers have a built-in Real Time Clock (RTC) unit, which may be used for counting time to maintain a calendar and clock. RTC is designed for low power designs that enable use in battery-powered designs. The real-time clock can count time in Seconds, Minutes, Hours, Days of Month, Months, Years, Days of the week, and Days of Year. The real-time module can be clocked using a distinct 32kHz clock oscillator or internal prescaller from the VPB clock. The real-time clock unit has additional power supply pins (3.3V) that allow the RTC clock to work when the system is off – actually power-down mode operated from the clock battery. As there are many functions in clocks like time units(seconds, minutes, etc.) and alarms, there are quite some registers to cover clock functionality. There are several groups of registers: