Datasheet

Section 3 Exception Handling
Page 72 of 982 REJ09B0465-0300 Rev. 3.00
Sep 17, 2010
H8S/20103, H8S/20203, H8S/20223, H8S/20115, H8S/20215, H8S/20235 Group
3.5 Interrupt Exception Handling
Interrupts are controlled by the interrupt controller. The interrupt controller has two interrupt
control modes and can assign interrupts other than NMI to four priority/mask levels to enable
multiplexed interrupt control. The source to start interrupt exception handling and the vector
address differ depending on the product. For details, see section 4, Interrupt Controller.
The interrupt exception handling is as follows:
1. The values in the program counter (PC), condition code register (CCR), and extended register
(EXR) are saved in the stack.
2. The interrupt mask bit is updated and the T bit is cleared to 0.
3. A vector address corresponding to the interrupt source is generated, the start address is loaded
from the vector table to the PC, and program execution starts from that address.
3.6 Trap Instruction Exception Handling
Trap instruction exception handling starts when a TRAPA instruction is executed. Trap instruction
exception handling can be executed at all times in the program execution state.
The trap instruction exception handling is as follows:
1. The values in the program counter (PC), condition code register (CCR), and extended register
(EXR) are saved in the stack.
2. The interrupt mask bit is updated and the T bit is cleared to 0.
3. A vector address corresponding to the interrupt source is generated, the start address is loaded
from the vector table to the PC, and program execution starts from that address.
The TRAPA instruction fetches a start address from a vector table entry corresponding to a vector
number from 0 to 3, as specified in the instruction code.
Table 3.4 shows the status of CCR and EXR after execution of trap instruction exception handling.