Renesas M16C/29 Series Hardware Manual page 341

M16C/29 Group
Digital Debounce Filter
Clock
f
8
P8 / P1 Port In
5 7
Data Bus Reload Value
(write)
f
8
Reload Value
FF
Port In
Signal Out
Count Value
FF
1
Reload Value 03
(continued)
Port In
(continued)
Signal Out
(continued)
Count Value FF
(continued)
1. (Condition after reset). Reload = FF, Port In = signal Out continuosly.
2. Reload = 03. At edge of Port In != Signal Out, Counter gets Reload Value and
stats counting down.
3. Port In = Signal Out, counting stops.
4. At edge of Port In != Signal Out, Counter gets Reload Value and starts counting.
5. Counter underflows, stops, and Port In is driven to Signal Out.
6. At edge of Port In != Signal Out, counter gets Reload Value and starts counting.
7. Counter underflows, stops, and Port In is driven to Signal Out.
8. At edge of Port In != Signal Out, counter gets Reload Value and starts counting.
9. FF is written to Reload Value. Counter is stopped and loaded with FF.
Port In = Signal Out continuously.
Figure 19.6.2. Functioning of Digital Debounce Filter
Rev.1.00 Nov 01,2004
REJ09B0101-0100Z
Signal Out
Count Value
(read)
03
03
02
2
03 01
02 00
6
7
page 321 of 402
To NMI and SD / INT5 and INPC17
Data Bus
01 03
3
4
FF
03 FF
FF 02
8
9
19. Programmable I/O Ports
02 01 00 FF
5