D12320VF25IV Datasheet, PDF (618/1304 Pages) Renesas Technology Corp – Old Company Name in Catalogs and Other Documents

Section 13 Watchdog Timer
Bit 6
WT/IT
Description
0
Interval timer: Sends the CPU an interval timer interrupt request (WOVI)
when TCNT overflows
(Initial value)
1
Watchdog timer: Generates the WDTOVF signal^*1 when TCNT overflows^*2
Notes: 1. The WDTOVF pin function cannot be used in the F-ZTAT versions.
2. For details of the case where TCNT overflows in watchdog timer mode, see section
13.2.3, Reset Control/Status Register (RSTCSR).
Bit 5—Timer Enable (TME): Selects whether TCNT runs or is halted.
Bit 5
TME
0
1
Description
TCNT is initialized to H'00 and halted
TCNT counts
(Initial value)
Bits 4 and 3—Reserved: These bits cannot be modified and are always read as 1.
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 (φ), for input to TCNT.
Description
Bit 2 Bit 1 Bit 0
CKS2 CKS1 CKS0 Clock
Overflow Period (when φ = 20 MHz)^*
0
0
0
φ/2 (Initial value) 25.6 µs
1
φ/64
819.2 µs
1
0
φ/128
1.6 ms
1
φ/512
6.6 ms
1
0
0
φ/2048
26.2 ms
1
φ/8192
104.9 ms
1
0
φ/32768
419.4 ms
1
φ/131072
1.68 s
Note: * The overflow period is the time from when TCNT starts counting up from H'00 until overflow
occurs.
Rev.6.00 Sep. 27, 2007 Page 586 of 1268
REJ09B0220-0600