
2.2.9 Real-time Clock


The TT030 system includes a Real-time Clock chip. When the system is powered on the real-time clock is powered by the main PCB power supply. In the event of a power failure, or when the system is powered off, the real-time clock is powered by a 3.6v lithium battery. This allows the date, time, and configuration data to be maintained even when there is no power to the unit. 50 bytes of battery backed-up RAM is also provided for storing diagnostic and configuration data.

The real-time clock provides time of day (down to one second resolution) and date. The RTC is provided with a 32.760 kHz oscillator that is independent of all other system clocks. The chip is accessed through two consecutive word ports. The first word is a write-only port used to set the real-time clock chip address desired. The second word is the read-write data port. When doing a write to a clock chip register, a double word write can be performed. The first word would set the address, and the second word would load the data.
