606
TCSR—Timer Control/Status Register
H'FFBC (W) H'FFBC (R)
WDT
Bit
Initial value
Read/Write
7
OVF
0
R/(W)
*
1
6
WT/
IT
0
R/W
5
TME
0
R/W
4
—
1
—
3
—
1
—
2
CKS2
0
R/W
1
CKS1
0
R/W
0
CKS0
0
R/W
CKS2
Clock Select
0
1
Clock
ø/2 (Initial value)
ø/64
ø/128
ø/512
ø/2048
ø/8192
ø/32768
ø/131072
CKS1
0
1
0
1
CKS0
0
1
0
1
0
1
0
1
Overflow Period
*
(when ø = 20 MHz)
25.6
µ
s
819.2
µ
s
1.6 ms
6.6 ms
26.2 ms
104.9 ms
419.4 ms
1.68 s
0 TCNT is initialized to H'00 and halted
TCNT counts
Timer Enable
1
Note:
*
The overflow period is the time from when TCNT
starts counting up from H'00 until overflow occurs.
0 Interval timer mode: Sends the CPU an interval timer interrupt
request (WOVI) when TCNT overflows
Watchdog timer mode: Outputs the
WDTOVF
signal
*
2
externally when TCNT overflows
Timer Mode Select
1
0 [Clearing condition]
When 0 is written to OVF after reading TCSR when OVF = 1
[Setting condition]
When TCNT overflows (from H'FF to H'00) in interval timer mode.
When internal reset requests are selected in watchdog timer mode,
however, after being set OVF is cleared automatically by an internal reset.
Overflow Flag
1
The method for writing to TCSR is different from that for general registers to prevent accidental
overwriting. For details see section 11.2.4, Notes on Register Access, in the H8S/2678 Series
Hardware Manual.
Notes: 1. Can only be written with 0, to clear the flag.
2. The
WDTOVF
function is not available in the F-ZTAT version.
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