CHAPTER 3 CPU FUNCTION
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User’s Manual U15195EJ5V0UD
(2) NMI status saving registers (FEPC, FEPSW)
There are two NMI status saving registers, FEPC and FEPSW.
Upon occurrence of a non-maskable interrupt (NMI), the contents of the program counter (PC) are saved to
FEPC and the contents of the program status word (PSW) are saved to FEPSW.
The address of the next instruction following the instruction executed when a non-maskable interrupt occurs is
saved to FEPC, except for some instructions.
The current PSW contents are saved to FEPSW.
Bits 31 to 26 of FEPC and bits 31 to 8 of FEPSW are reserved (fixed to 0) for future function expansion.
When the RETI instruction has been executed, the values of FEPC and FEPSW are restored to the PC and
PSW, respectively.
31
0
FEPC
(PC contents saved)
0
0
After reset
0xxxxxxxH
(x: Undefined)
26 25
0 0 0 0
31
0
FEPSW
(PSW contents saved)
0
0
After reset
000000xxH
(x: Undefined)
8
0 0 0 0
0
0
0 0 0 0
0
0
0 0 0 0
0
0
0 0 0 0
7
(3) Interrupt source register (ECR)
Upon occurrence of an interrupt or an exception, the interrupt source register (ECR) holds the source of an
interrupt or an exception. The value held by ECR is the exception code coded for each interrupt source. This
register is a read-only register, and thus data cannot be written to it using the LDSR instruction.
31
0
ECR
FECC
EICC
After reset
00000000H
16 15
Bit position
Bit name
Description
31 to 16
FECC
Non-maskable interrupt (NMI) exception code
15 to 0
EICC
Exception, maskable interrupt exception code
Содержание PD703114
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