CHAPTER 5 INTERRUPT/EXCEPTION PROCESSING FUNCTION
User’s Manual U13850EJ4V0UM
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5.2.5 Edge detection function of NMI pin
The NMI pin valid edge can be selected from the following four types: falling edge, rising edge, both edges,
detects neither rising nor falling edge.
Rising edge specification register 0 (EGP0) and falling edge specification register 0 (EGN0) specify the valid edge
of the non-maskable interrupt (NMI). These two registers can be read/written in 1-bit or 8-bit units.
After reset, the valid edge of the NMI pin is set to the “detects neither rising nor falling edge” state. Therefore, the
NMI pin functions as a normal port and an interrupt request cannot be acknowledged, unless a valid edge is specified
by using the EGP0 and EGN0 registers.
When using P00 as an output port, set the NMI valid edge to “detects neither rising nor falling edge”.
Figure 5-5. Rising Edge Specification Register 0 (EGP0) Format
After reset: 00H
R/W
Address: FFFFF0C0H
Symbol
<7>
<6>
<5>
<4>
<3>
<2>
<1>
<0>
EGP0
EGP07
EGP06
EGP05
EGP04
EGP03
EGP02
EGP01
EGP00
EGP0n
Rising edge valid control
0
No interrupt request signal occurs at the rising edge
1
Interrupt request signal occurs at the rising edge
n = 0: NMI pin control
n = 1 to 7: INTP0 to INTP6 pins control
Figure 5-6. Falling Edge Specification Register 0 (EGN0) Format
After reset: 00H
R/W
Address: FFFFF0C2H
Symbol
<7>
<6>
<5>
<4>
<3>
<2>
<1>
<0>
EGN0
EGN07
EGN06
EGN05
EGN04
EGN03
EGN02
EGN01
EGN00
EGN0n
Falling edge valid control
0
No interrupt request signal occurs at the falling edge
1
Interrupt request signal occurs at the falling edge
n = 0: NMI pin control
n = 1 to 7: INTP0 to INTP6 pins control