HD6475328-CP10 Datasheet, PDF (259/459 Pages) Hitachi Semiconductor – original Hitachi CMOS microcomputer unit (MCU)

Write cycle: CPU writes to TCNT
T1
T2
T3
ø
Internal address bus
Internal write signal
TCNT clock pulse
TCNT address
TCNT
N
M
Counter write data
Figure 13-6 TCNT Write-Increment Contention
2. Changing the Clock Select Bits (CKS2 to CKS0): Software should stop the watchdog timer
(by clearing the TME bit to 0) before changing the value of the clock select bits. If the clock
select bits are modified while the watchdog timer is running, the timer count may be
incremented incorrectly.
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