Register Configuration; Wdt Register Descriptions; Watchdog Timer Counter (Wtcnt); Table 10.5 Wdt Registers - Hitachi SH7751 Hardware Manual

10.7.2

Register Configuration

The WDT has the two registers summarized in table 10.5. These registers control clock selection
and timer mode switching.

Table 10.5 WDT Registers

Name
Watchdog timer
counter
Watchdog timer
control/status
register
Note: * Use word-size access when writing. Perform the write with the upper byte set to H'5A or
H'A5, respectively. Byte- and longword-size writes cannot be used.
Use byte access when reading.
10.8

WDT Register Descriptions

10.8.1

Watchdog Timer Counter (WTCNT)

The watchdog timer counter (WTCNT) is an 8-bit readable/writable counter that counts up on the
selected clock. When WTCNT overflows, a reset is generated in watchdog timer mode, or an
interrupt in interval timer mode. WTCNT is initialized to H'00 only by a power-on reset via the


pin.
To write to the WTCNT counter, use a word-size access with the upper byte set to H'5A. To read
WTCNT, use a byte-size access.
Bit: 7
Initial value: 0
R/W: R/W
Rev. 3.0, 04/02, page 254 of 1064
Abbreviation R/W
WTCNT R/W*
WTCSR R/W*
6 5
0 0
R/W R/W
Initial
Value P4 Address
H'00 H'FFC00008
H'00 H'FFC0000C
4 3
0 0
R/W R/W
Area 7
Address Access Size
H'1FC00008 R: 8, W: 16*
H'1FC0000C R: 8, W: 16*
2 1
0 0
R/W R/W R/W
0
0