Chetan:
If you go to the Cygnal Web site and look at application note AN030 you can see a sample program that shows how to pack temperature and time information into records and write them into external memory. This application note is designed to show how these records can be written into FLASH on a Cygnal micro controller using bank switching on a part with 128K bytes of FLASH. However I am sure that in looking at the code you will see some good ideas to work with.
Hope this helps.
Michael Karas