While sending the data through on-chip I2C of LPC2148, we like to know the significance of clearing the SIC bit (I2C0CONCLR=0x08)for each transaction (address,data,stop)even though we are not using the interrupt.
Besides being able to turn off all main clocking and still have the RTC running with the 32.768kHz crystal, that lower frequency crystal also has the advantage that it is more stable - a crystal running at that low frequency is larger and heavier than a 12MHz crystal which makes it less affected by contamination inside the crystal casing.