The code using FlashPrimitives.c worked finally.

Nothing wrong with that. The actual problem was that the write to flash does not happen when used with the "for" loop as I had done. I even tried to use the status of the FLBUSY bit after each write. No luck. I am now calling the Flash_WriteByte function 4 times to store my 4 digits like this :

FLASH_PageErase (EraseAddr,1);
FLASH_ByteWrite (OnTimeAddr + 0, OnDigit[0], 1);
FLASH_ByteWrite (OnTimeAddr + 1, OnDigit[1], 1);
FLASH_ByteWrite (OnTimeAddr + 2, OnDigit[2], 1);
FLASH_ByteWrite (OnTimeAddr + 3, OnDigit[3], 1);
 

Of course I can sit and analyse the source code to know why but then I am happy that it works and thats it.

And Erik, thanks for the link. Yes that forum seems to be quite an active one.

Raghu