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14.2.3 NP flag
The NP flag is a status flag that indicates that non-maskable interrupt servicing is under execution.
This flag is set when a non-maskable interrupt request has been acknowledged, and masks non-maskable
interrupt requests to prohibit multiple interrupts from being acknowledged.
After reset:
00000020H
PSW
NP
0
1
14.2.4 Eliminating noise on NMI pin
The NMI pin has a noise eliminator that eliminates noise using analog delay. Unless the level input to the NMI pin
is held for a specific time, therefore, it cannot be detected as an edge i.e., the edge is detected after specific time.
The NMI pin is used to release the software STOP mode. Because the internal system clock is stopped in the
software STOP mode, noise is not eliminated by using the system clock.
14.2.5 Function to detect edge of NMI pin
The valid edge of the NMI pin can be selected from four types: "rising edge", "falling edge", "both edges", and "no
edge detection".
Specify the valid edge of the non-maskable interrupt (NMI) by using rising edge specification register 0 (INTR0)
and falling edge specification register 0 (INTF0). These registers can be read or written in 8-bit or 1-bit units.
After reset, it is specified that "no edge is detected" on the NMI pin. Unless the valid edge is specified by the
INTF0 and INTR0 registers, therefore, an interrupt request is not acknowledged (the NMI pin serves as a port pin).
To use the P00/NMI pin as an I/O port pin, specify that the valid edge of the NMI pin is "no edge detection".
CHAPTER 14 INTERRUPT/EXCEPTION PROCESSING FUNCTION
0
Non-maskable interrupt servicing status
No non-maskable interrupt servicing
Non-maskable interrupt currently being serviced
Preliminary User's Manual U15905EJ1V0UD
NP
EP
ID SAT CY OV
S
Z
425
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