CHAPTER 7 INTERRUPT/EXCEPTION PROCESSING FUNCTION
User’s Manual U15109EJ3V0UD
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7.2.5 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,
neither rising nor falling edge detected.
Rising edge specification register 0 (EGP0) and falling edge specification register 0 (EGN0) specify the valid edge
of non-maskable interrupts (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 “neither rising nor falling edge detected” 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 “neither rising nor falling edge detected”.
(1) Format of rising edge specification register 0 (EGP0)
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 validity 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
(2) Format of falling edge specification register 0 (EGN0)
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 validity 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