Register Controlling Key Interrupt - NEC 78K0 User Manual

16.3 Register Controlling Key Interrupt

(1) Key return mode register (KRM)
This register controls the KRM0 to KRM3 bits using the KR0 to KR3 signals, respectively.
This register is set by a 1-bit or 8-bit memory manipulation instruction.
RESET input clears this register to 00H.
Address: FF6EH
Symbol
KRM
Cautions 1. If any of the KRM0 to KRM3 bits used is set to 1, set bits 0 to 3 (PU70 to PU73) of the
corresponding pull-up resistor register 7 (PU7) to 1.
2. If KRM is changed, the interrupt request flag may be set. Therefore, disable interrupts and
then change the KRM register. Clear the interrupt request flag and enable interrupts.
3. The bits not used in the key interrupt mode can be used as normal ports.
CHAPTER 16 KEY INTERRUPT FUNCTION
Figure 16-2. Format of Key Return Mode Register (KRM)
After reset: 00H R/W
7 6 5
0 0 0
KRMn
0 Does not detect key interrupt signal
1 Detects key interrupt signal
User's Manual U16227EJ2V0UD
4 3 2
0 KRM3 KRM2
Key interrupt mode control
0
KRM1 KRM0
331