308
10.1.2 Block Diagram
Figure 10-1 shows a block diagram of the WDT.
ø/2
ø/32
ø/64
ø/128
ø/256
ø/512
ø/2048
ø/4096
TCNT
TCSR
RSTCSR
Reset control
Interrupt signal
Reset
(internal, external)
(interval timer)
Interrupt
control
Overflow
Clock
Clock
selector
Read/
write
control
Internal
data bus
Internal clock sources
Legend
TCNT:
TCSR:
RSTCSR:
Timer counter
Timer control/status register
Reset control/status register
Figure 10-1 WDT Block Diagram
10.1.3 Pin Configuration
Table 10-1 describes the WDT output pin.*
1
Table 10-1 WDT Pin
Name
Abbreviation
I/O
Function
Reset output
RESO
Output
*
2
External output of the watchdog timer reset signal
Notes: 1. Shows the masked ROM version pin. The F-ZTAT does not have any pins used by the
WDT. For F-ZTAT version, see section 15.11 Notes on Flash Memory
Programming/Erasing.
2. Open-drain output. Externally pull-up to Vcc whether or not the reset output is used