NEC PD78F9488 - Manual (Page 300)

CHAPTER 16 INTERRUPT FUNCTIONS
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User’s Manual U15331EJ4V1UD
(6) Key return mode register 01 (KRM01) ( µPD789489, 78F9489 only)
This register is used to set the pin that is to detect the key return signal (falling edge of port 6).
KRM01 is set with a 1-bit or 8-bit memory manipulation instruction.
RESET input sets this register to 00H.
Figure 16-8. Format of Key Return Mode Register 01
Symbol 7 6 5 4 3 2 1 0 Address After reset R/W
KRM01 KRM017 KRM016 KRM015 KRM014 0 0 0 KRM010 FFF4H 00H R/W
KRM010 Control of key return signal detection
0 Key return signal not detected
1 Key return signal detected (P60 to P63 falling edge detection)
KRM01n Control of key return signal detection
0 Key return signal not detected
1 Key return signal detected (P6n falling edge detection)
Remark n = 4 to 7
Cautions 1. Always set bits 1 to 3 to 0.
2. Before setting KRM01, set bit 5 of MK2 (KRMK01 = 1) to disable interrupts. To enable
interrupts, clear KRMK01 after clearing bit 5 of IF2 (KRIF01 = 0)
3. If any of the pins specified for key return signal detection is low level, the key return
signal cannot be detected even if a falling edge is generated at other key return pins.
4. When even one of the P60/ANI0/KR10 to P67/ANI7/KR17 pins is used as an A/D input, set
KRM010 and KRM014 to KRM017 to 0.
Figure 16-9. Block Diagram of Falling Edge Detector
P60/ANI0/KR10
P61/ANI1/KR11
P62/ANI2/KR12
P63/ANI3/KR13
P64/ANI4/KR14
P65/ANI5/KR15
P66/ANI6/KR16
P67/ANI7/KR17 KRMK01
INTKR01 Falling edge detector
Standby release
signal
Key return mode register 01
(KRM01)
Selector
Note
Note For selecting the pin to be used as falling edge input