DF2211NP24V Renesas Technology / Hitachi Semiconductor, DF2211NP24V Datasheet - Page 395

• Manufacturer Part Number: DF2211NP24V
• Description: H8S/2200 Series, 2212 Group, USB, RTC, HSS TNP-64B; Vcc= 2.7 to 3.6 volts, Temp= -20 to 75 C; Package: PVQN0064LB-A
• Manufacturer: Renesas Technology / Hitachi Semiconductor

Note: * The write value should always be 0 to clear this flag.
Bit
7
6
5
4, 3
2
1
0
Bit Name
OVF
WT/IT
TME
—
CKS2
CKS1
CKS0
Initial Value
0
0
0
All 1
0
0
0
R/W
R/(W)*
R/W
R/W
—
R/W
R/W
R/W
Description
Overflow Flag
Indicates that TCNT has overflowed. Only a write of
0 is permitted, to clear the flag.
[Setting condition]
When TCNT overflows (changes from H'FF to H'00)
When internal reset request generation is selected
in watchdog timer mode, OVF is cleared
automatically by the internal reset.
[Clearing condition]
Cleared by reading TCSR when OVF = 1, then
writing 0 to OVF
When polling CVF when the interval timer interrupt
has been prohibited, OVF = 1 status should be read
two or more times.
Timer Mode Select
Selects whether the WDT is used as a watchdog
timer or interval timer.
0: Interval timer mode
1: Watchdog timer mode
Timer Enable
When this bit is set to 1, TCNT starts counting.
When this bit is cleared, TCNT stops counting and
is initialized to H'00.
Reserved
These bits are always read as 1 and cannot be
modified.
Clock Select 0 to 2
Selects the clock source to be input to TCNT. The
overflow frequency for φ = 16 MHz is enclosed in
parentheses. The overflow period is the time from
when TCNT starts counting up from H'00 until
overflow occurs.
000: Clock φ/2 (frequency: 32.0 μs)
001: Clock φ/64 (frequency: 1.0 ms)
010: Clock φ/128 (frequency: 2.0 ms)
011: Clock φ/512 (frequency: 8.2 ms)
100: Clock φ/2048 (frequency: 32.8 ms)
101: Clock φ/8192 (frequency: 131.1 ms)
110: Clock φ/32768 (frequency: 524.3 ms)
111: Clock φ/131072 (frequency: 2.1 s)
Rev.7.00 Dec. 24, 2008 Page 341 of 698
REJ09B0074-0700