CHAPTER 7 INTERRUPT/EXCEPTION PROCESSING FUNCTION
User’s Manual U15109EJ3V0UD
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7.2.1 Operation
If a non-maskable interrupt is generated, the CPU performs the following processing, and transfers control to the
handler routine:
(1) Saves the restored PC to FEPC.
(2) Saves the current PSW to FEPSW.
(3) Writes the exception code (0010H, 0020H) to the higher halfword (FECC) of ECR.
(4) Sets the NP and ID bits of the PSW and clears the EP bit.
(5) Loads the handler address (00000010H, 00000020H) of the non-maskable interrupt routine to the PC, and
transfers control.
Figure 7-1. Non-Maskable Interrupt Servicing
NMI input
Non-maskable interrupt request
Interrupt servicing
Interrupt request pending
FEPC
FEPSW
ECR. FECC
PSW. NP
PSW. EP
PSW. ID
PC
restored PC
PSW
exception code
1
0
1
Handler address
00000010H (NMI)
00000020H (INTWDT)
Handler address:
INTC acknowledged
CPU processing
PSW. NP
1
0