h8s-2172 Renesas Electronics Corporation., h8s-2172 Datasheet - Page 315

• Manufacturer Part Number: h8s-2172
• Description: Renesas 16-bit Single-chip Microcomputer H8s Family H8s-2100 Series
• Manufacturer: Renesas Electronics Corporation.

This LSI incorporates an 8-bit watchdog timer with one channel (WDT). If a system crash
prevents the CPU from writing to the timer counter, thus allowing it to overflow, the WDT can
generate an internal reset signal or an internal NMI interrupt signal.
When this watchdog function is not needed, the WDT can be used as an interval timer. In interval
timer operation, an interval timer interrupt is generated each time the counter overflows. A block
diagram of the WDT is shown in figure 10.1.
10.1
• Selectable from eight counter input clocks.
• Switchable between watchdog timer mode and interval timer mode
Watchdog Timer Mode:
•
Internal Timer Mode:
•
If the counter overflows, an internal reset or an internal NMI interrupt is generated.
If the counter overflows, an internal timer interrupt (WOVI) is generated.
(Interrupt request signal)
(Interrupt request signal)
Internal reset signal
Internal NMI
Features
WOVI
Legend
TCSR : Timer control/status register
TCNT : Timer counter
Section 10 Watchdog Timer (WDT)
Interrupt
control
control
Reset
Figure 10.1 Block Diagram of WDT
Overflow
Module bus
TCNT
Clock
WDT
selection
Clock
TCSR
Rev. 2.00, 03/04, page 283 of 534
Internal clock
interface
φ/2
φ/64
φ/128
φ/512
φ/2048
φ/8192
φ/32768
φ/131072
Bus