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(3) Key return mode register (KRM)
This register is used to set enable/disable of standby function clear by key return signal (port 4 falling edge
detection).
KRM is set with a 1-bit or 8-bit memory manipulation instruction.
RESET input sets KRM to 02H.
Symbol
7
6
5
KRM
0
0
0
Caution When port 4 falling edge detection is used, clear KRIF to 0 (not cleared to 0 automatically).
22.5.2 Test input signal acknowledge operation
(1) Internal test signal
If the watch timer overflows, an internal test input signal (INTWT) is generated, by which the WTIF flag is
set. At this time, if it is not masked with the interrupt mask flag (WTMK), a standby release signal is generated.
The watch function is available by checking the WTIF flag at a shorter cycle than the watch timer overflow
cycle.
(2) External test signal
When a falling edge is input to the port 4 (P40 to P47) pins, an external test input signal (INTPT4) is generated,
by which the KRIF flag is set. At this time, if it is not masked with the interrupt mask flag (KRMK), a standby
release signal is generated. If port 4 is used as key matrix return signal input, whether or not a key input
has been applied can be checked from the KRIF status.
CHAPTER 22 INTERRUPT FUNCTIONS
Figure 22-21. Key Return Mode Register Format
4
3
2
<1>
<0>
0
0
0
KRMK
KRIF
After
Address
Reset
FFF6H
02H
KRIF
Key Return Signal
0
Not detected
1
Detected (port 4 rising edge detection)
KRMK
Standby Mode Control by Key Return Signal
0
Standby mode release enabled
1
Standby mode release disabled
R/W
R/W
525
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