
CHAPTER 19 INTERRUPT/EXCEPTION PROCESSING FUNCTION
User
’
s Manual U15862EJ3V0UD
620
19.2.5 Edge detection function for NMI pin
The NMI valid edge can be selected from the following four types: falling edge, rising edge, both edges, and no
edge detection.
Rising edge specification register 0 (INTR0) and falling edge specification register 0 (INTF0) specify the valid edge
of non-maskable interrupts (NMI). These two registers can be read/written in 8-bit or 1-bit units.
After reset, the edge detection for the NMI pin is set to
“
no edge detection
”
. Therefore, the NMI pin functions as a
normal port and interrupt requests cannot be acknowledged unless a valid edge is specified by the INTF0 and INTR0
registers.
When using P02 as an output port, set the NMI pin valid edge to
“
no edge detection
”
.
(1) External interrupt rising edge specification register 0 (INTR0)
This is an 8-bit register that specifies the rising edge of the NMI pin.
This register can be read/written in 8-bit or 1-bit units.
Caution
When switching to the port function from the external interrupt function (alternate function),
edge detection may be performed. Therefore, set the port mode after setting INTF0n = INTR0n =
0.
0
INTR0
INTR06
INTR05
INTR04
INTR03
INTR02
0
0
After reset : 00H R/W Address : FFFFFC20H
Remark
For specification of the valid edge, refer to
Table 19-4
.
(2) External interrupt falling edge specification register 0 (INTF0)
This is an 8-bit register that specifies the falling edge of the NMI pin.
This register can be read/written in 8-bit or 1-bit units.
Caution
When switching to the port function from the external interrupt function (alternate function),
edge detection may be performed. Therefore, set the port mode after setting INTF0n = INTR0n =
0.
0
INTF0
INTF06
INTF05
INTF04
INTF03
INTF02
0
0
After reset : 00H R/W Address : FFFFFC00H
Remark
For specification of the valid edge, refer to
Table 19-4
.