Register Controlling Key Interrupt - NEC 78K0 User Manual

20.3 Register Controlling Key Interrupt

(1) Key return mode register (KRM)
This register controls the KRM0 to KRM7 bits using the KR0 to KR7 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 KRM7 bits used is set to 1, set bits 0 to 7 (PU70 to PU77) 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 20 KEY INTERRUPT FUNCTION
Figure 20-2. Format of Key Return Mode Register (KRM)
After reset: 00H R/W
7 6 5
KRM7 KRM6 KRM5
KRMn
0 Does not detect key interrupt signal
1
Detects key interrupt signal
User's Manual U15947EJ2V0UD
4 3 2
KRM4 KRM3 KRM2
Key interrupt mode control
*
0
KRM1 KRM0
447