D12320VF25IV Datasheet, PDF (616/1304 Pages) Renesas Technology Corp – Old Company Name in Catalogs and Other Documents

Section 13 Watchdog Timer
13.2 Register Descriptions
13.2.1 Timer Counter (TCNT)
Bit
:
7
6
5
4
3
2
1
0
Initial value :
0
0
0
0
0
0
0
0
R/W
: R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
TCNT is an 8-bit readable/writable*¹ up-counter.
When the TME bit is set to 1 in TCSR, TCNT starts counting pulses generated from the internal
clock source selected by bits CKS2 to CKS0 in TCSR. When the count overflows (changes from
H'FF to H'00), either the watchdog timer overflow signal (WDTOVF)*² or an interval timer
interrupt (WOVI) is generated, depending on the mode selected by the WT/IT bit in TCSR.
TCNT is initialized to H'00 by a reset, in hardware standby mode, or when the TME bit is cleared
to 0. It is not initialized in software standby mode.
Notes: 1. TCNT is write-protected by a password to prevent accidental overwriting. For details
see section 13.2.4, Notes on Register Access.
2. The WDTOVF pin function cannot be used in the F-ZTAT versions.
Rev.6.00 Sep. 27, 2007 Page 584 of 1268
REJ09B0220-0600