upd70f3017ay Renesas Electronics Corporation., upd70f3017ay Datasheet - Page 117

• Manufacturer Part Number: upd70f3017ay
• Description: V850/sa1tm 32-/16-bit Single-chip Microcontroller
• Manufacturer: Renesas Electronics Corporation.

5.3.2 Restore
(1) Restores the values of the PC and PSW from EIPC and EIPSW because the EP bit of the PSW is 0 and the
(2) Transfers control to the address of the restored PC and PSW.
To restore execution from maskable interrupt servicing, the RETI instruction is used.
Operation of RETI instruction
Caution When the PSW.EP bit and the PSW.NP bit are changed by the LDSR instruction during
Remark
When the RETI instruction is executed, the CPU performs the following steps, and transfers control to the address
of the restored PC.
The processing of the RETI instruction is shown below.
NP bit of the PSW is 0.
maskable interrupt servicing, in order to restore the PC and PSW correctly during recovery
by the RETI instruction, it is necessary to set PSW.EP back to 0 and PSW.NP back to 0 using
the LDSR instruction immediately before the RETI instruction.
The solid line shows the CPU processing flow.
1
CHAPTER 5 INTERRUPT/EXCEPTION PROCESSING FUNCTION
Original processing restored
PC
PSW
RETI instruction
Figure 5-6. RETI Instruction Processing
PSW. EP
PSW. NP
0
0
EIPC
EIPSW
User’s Manual U12768EJ4V1UD
1
PC
PSW
FEPC
FEPSW
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