upd70f3402 Renesas Electronics Corporation., upd70f3402 Datasheet - Page 715

• Manufacturer Part Number: upd70f3402
• Description: 32-/16-bit Single-chip Microcontroller With Can Interface
• Manufacturer: Renesas Electronics Corporation.

17.4.2 Restore
Recovery from software exception processing is carried out by the RETI instruction.
By executing the RETI instruction, the CPU carries out the following processing and shifts control to the
restored PC’s address.
<1> Loads the restored PC and PSW from EIPC and EIPSW because the EP bit of the PSW is 1.
<2> Transfers control to the address of the restored PC and PSW.
Figure 17-25 illustrates the processing of the RETI instruction.
Caution:
Remark:
When the PSW.EP bit and the PSW.NP bit are changed by the LDSR instruction dur-
ing the software exception processing, in order to restore the PC and PSW correctly
during recovery by the RETI instruction, it is necessary to set PSW.EP back to 1
using the LDSR instruction immediately before the RETI instruction.
The solid line shows the CPU processing flow.
1
Chapter 17 Interrupt/Exception Processing Function
Original processing restored
PC
PSW
Figure 17-25: RETI Instruction Processing
RETI instruction
User’s Manual U16702EE3V2UD00
PSW.EP
PSW.NP
0
0
EIPC
EIPSW
1
PC
PSW
FEPC
FEPSW
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