HD6473032F16 Datasheet, PDF (107/847 Pages) Renesas Technology Corp – Hardware Manual Renesas 16-Bit Single-Chip Microcomputer H8 Family/H8/300H Series

Section 4 Exception Handling
4.4 Trap Instruction
Trap instruction exception handling starts when a TRAPA instruction is executed. If the UE bit is
set to 1 in the system control register (SYSCR), the exception handling sequence sets the I bit to 1
in CCR. If the UE bit is 0, the I and UI bits are both set to 1. The TRAPA instruction fetches a
start address from a vector table entry corresponding to a vector number from 0 to 3, which is
specified in the instruction code.
4.5 Stack Status after Exception Handling
Figure 4.6 shows the stack after completion of trap instruction exception handling and interrupt
exception handling.
SP-4
SP-3
SP-2
SP-1
SP (ER7) ^→
Stack area
SP (ER7) →
SP+1
SP+2
SP+3
SP+4
CCR
PC _E
PC _H
PC _L
Even address
Before exception handling
After exception handling
Pushed on stack
Legend:
PCE: Bits 23 to 16 of program counter (PC)
PCH: Bits 15 to 8 of program counter (PC)
PCL: Bits 7 to 0 of program counter (PC)
CCR: Condition code register
SP: Stack pointer
Notes: 1. PC indicates the address of the first instruction that will be executed after return.
2. Register saving and restoration must be carried out in word or longword size at even
addresses.
Figure 4.6 Stack after Completion of Exception Handling
Rev. 3.00 Mar 21, 2006 page 77 of 814
REJ09B0302-0300