Interrupts; Usage Notes; Contention Between Timer Counter (Tcnt) Write And Increment - Hitachi H8S/2646 Hardware Manual

12.4

Interrupts

During interval timer mode operation, an overflow generates an interval timer interrupt (WOVI).
The interval timer interrupt is requested whenever the OVF flag is set to 1 in TCSR. OVF must be
cleared to 0 in the interrupt handling routine.
If an NMI request has been chosen in the watchdog timer mode, an NMI request is generated
when a TCNT overflow occurs.
12.5

Usage Notes

12.5.1

Contention between Timer Counter (TCNT) Write and Increment

If a timer counter clock pulse is generated during the T
takes priority and the timer counter is not incremented. Figure 12-8 shows this operation.
ø
Address
Internal write signal
TCNT input clock
TCNT
Figure 12-8 Contention between TCNT Write and Increment
state of a TCNT write cycle, the write
2
TCNT write cycle
T T
1 2
N
Counter write data
M
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