420
WDT0 TCSR Bit 3—Reserved Bit: It is always read as 1 and cannot be modified.
WDT1 TCSR Bit 3—Reset or NMI (RST/
NMI
): This bit is used to choose between an internal
reset request and an NMI request when the TCNT overflows during the watchdog timer mode.
Bit 3
RTS/
NMI
Description
0
NMI request.
(Initial value)
1
Internal reset request.
Bits 2 to 0—Clock Select 2 to 0 (CKS2 to CKS0): These bits select one of eight internal clock
sources, obtained by dividing the system clock (ø) or subclock (ø SUB), for input to TCNT.
WDT0 Input Clock Select
Description
Bit 2
CKS2
Bit 1
CKS1
Bit 0
CKS0
Clock
Overflow Period
*
(where ø = 20 MHz)
0
0
0
ø/2 (initial value)
25.6 µs
1
ø/64
819.2 µs
1
0
ø/128
1.6 ms
1
ø/512
6.6 ms
1
0
0
ø/2048
26.2 ms
1
ø/8192
104.9 ms
1
0
ø/32768
419.4 ms
1
ø/131072
1.68 s
Note:
*
An overflow period is the time interval between the start of counting up from H'00 on the
TCNT and the occurrence of a TCNT overflow.
Summary of Contents for H8S/2645
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Page 837: ...805 A 2 Instruction Codes Table A 2 shows the instruction codes ...
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