The PIC18(L)F27/47K40 devices have multiple interrupt sources and an interrupt priority feature that allows most interrupt sources to be assigned a high or low priority level. The high priority interrupt vector is at 0008h and the low priority interrupt vector is at 0018h. A high priority interrupt event will interrupt a low priority interrupt that may be in progress.

The registers for controlling interrupt operation are:

It is recommended that the Microchip header files supplied with MPLAB® IDE be used for the symbolic bit names in these registers. This allows the assembler/compiler to automatically take care of the placement of these bits within the specified register.

In general, interrupt sources have three bits to control their operation. They are: