Hi Nilson
I´m sure that there´s no difference on 80 to 112 pins chips regarding to FEC functionality.
All the registers are the same on same addresses.
I developed my firmware on M5223DEMO board, wich has an 80 pins PCF52233 and on my custom board I´m using PCF52235CAL60 (112 pins) and the exact same code runs smooth.
Regarding to the debugging error message, it happens because you are setting up too many breakpoints. Try to set up only one breakpoint at the fec init code, and after reach it try to disable that breakpoint and single step through the code.
One thing that really affects the FEC functionality is your power source. You must be sure it can supply enough current for the FEC to start.
Hope this helps
Regards