1) You have the data sheet for your AT89LP4052. If not you should have it.

2) You have a sample header file. You say the AT892051.h file is available.

3) Make a copy of AT892051.h and name it AT89LP4052.h. Cut off the AT in the name if your tools set requires 8 character file names.

4) Open a text editor with AT89LP4052.h and following the sample format go through the SFR table from the data sheet and add in all the SFRs that missing.

5) Now include this modified header file in your sources and your good to go.

Note that there is nothing magic about these header files. You are free to make new ones at will!!

Michael Karas