To replace the display with ili9486, you need to modify the ili9341_init_seq[] at line 151 of ili9341.c and change the LCD width and height at various files. But if you want to replace with ili9488, there will be more work. Please see my post at
/g/nanovna-users/message/5322You can find the places to change the LCD width and height at my change list. Just look for "LCD_*".
Ken
