You should actually consider making them one program. Your life can be a lot easier. Plus you then need only make one software release. The loader you write can be designed to reject re-programming itself and ignore those requests. It can also compare the HEX records in the load area with the loader itself to make sure that the loader portion is the same as the original loader. If you are working in Keil tools there is a cool mechanism that allows the main application interrupt vector table to be offset to a code boundary just above the loader area.

If you want more info on this see my concept posting at the Keil web site at:


http://www.keil.com/discuss/docs/thread2901.htm

Note that I have implemented this IAP scheme and it works GREAT.

Michael Karas