Control Register; Cautions - NEC V850ES/F 3-L Series User Manual

Chapter 6

6.2 Control Register

(1)
Access
Address
Initial Value
Table 6-2
Bit name
KRMn
Caution
Note

6.3 Cautions

258
KRM - Key return mode register
The KRM register controls the KRM0 to KRM7 bits using the KR0 to KR7
signals.
This register can be read/written in 8-bit or 1-bit units.
FFFF F300 .
H
00 . This register is cleared by any reset.
H
7 6 5
KRM7 KRM6 KRM5
R/W R/W R/W
LOCKR register contents
Control of key return mode:
0: Does not detect key return signal.
1: Detects key return signal.
If the KRM register is changed, the interrupt request signal INTKR may be
generated. To prevent this, change the KRM register after disabling interrupts
(DI), and then enable interrupts (EI) after clearing the interrupt request flag
(KRIC.KRIF = 0).
For the alternate-function pin settings, see "Pin Functions" on page 31.
1. If a low level is input to any of the KR0 to KR7 pins, the INTKR signal is not
generated even if the falling edge of another pin is input.
2. If the KRM register is changed, an interrupt request signal (INTKR) may be
generated. To prevent this, change the KRM register after disabling
interrupts (DI), and then enable interrupts (EI) after clearing the interrupt
request flag (KRIC.KRIF bit) to 0.
3. To use the Key Interrupt Function, be sure to set the port pin to the key
return pin and then enable the operation with the KRM register. To switch
from the key return pin to the port pin, disable the operation with the KRM
register and then set the port pin.
4. Before writing a new value to the KRM register write a value of 0x00 to the
KRM register first.
User's Manual U18743EE1V2UM00
4 3 2
KRM4 KRM3 KRM2
R/W R/W R/W
Function
Key Interrupt Function
1 0
KRM1 KRM0
R/W R/W