HD64F2145 Datasheet, PDF (367/829 Pages) Renesas Technology Corp – Hitachi 16-Bit Single-Chip Microcomputer

14.2 Input/Output Pins
The WDT has the pins listed in table 14.1.
Table 14.1 Pin Configuration
Name
Reset output pin
Symbol
5(62
I/O
Output
External sub-clock
input pin
EXCL
Input
Function
Outputs the counter overflow signal in
watchdog timer mode
Inputs the clock pulses to the WDT_1
prescaler counter
14.3 Register Descriptions
The WDT has the following registers. To prevent accidental overwriting, TCSR and TCNT have
to be written to in a method different from normal registers. For details, refer to section 14.6.1,
Notes on Register Access. For details on the system control register, refer to section 3.2.2, System
Control Register (SYSCR).
• Timer counter (TCNT)
• Timer control/status register (TCSR)
14.3.1 Timer Counter (TCNT)
TCNT is an 8-bit readable/writable up-counter.
TCNT is initialized to H'00 when the TME bit in the timer control/status register (TCSR) is
cleared to 0.
Rev. 2.0, 08/02, page 327 of 788