Rev.6.00 Oct.28.2004 page 463
of 1016
REJ09B0138-0600H
13.5 Usage
Notes
13.5.1
Contention between Timer Counter (TCNT) Write and Increment
If a timer counter clock pulse is generated during the T
2
state of a TCNT write cycle, the write takes priority and the timer
counter is not incremented. Figure 13-8 shows this operation.
Address
ø
Internal write signal
TCNT input clock
TCNT
N
M
T
1
T
2
TCNT write cycle
Counter write data
Figure 13-8 Contention between TCNT Write and Increment
13.5.2
Changing Value of CKS2 to CKS0
If bits CKS2 to CKS0 in TCSR are written to while the WDT is operating, errors could occur in the incrementation.
Software must stop the watchdog timer (by clearing the TME bit to 0) before changing the value of bits CKS2 to CKS0.
13.5.3
Switching between Watchdog Timer Mode and Interval Timer Mode
If the mode is switched from watchdog timer to interval timer, or vice versa, while the WDT is operating, errors could
occur in the incrementation. Software must stop the watchdog timer (by clearing the TME bit to 0) before switching the
mode.
13.5.4
System Reset by
WDTOVF
Signal
If the
WDTOVF
output signal* is input to the
RES
pin of the H8S/2357 Group, the H8S/2357 Group will not be
initialized correctly. Make sure that the
WDTOVF
signal* is not input logically to the
RES
pin. To reset the entire system
by means of the
WDTOVF
signal*, use the circuit shown in figure 13-9.
Note: * The
WDTOVF
pin function is not available in the F-ZTAT version, the H8S/2398, H8S/2394, H8S/2392 or
H8S/2390.
Содержание ZTAT H8S/2357F
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Страница 1047: ...H8S 2357 Group H8S 2357F ZTATTM H8S 2398F ZTATTM Hardware Manual 2 6 2 Ote machi Chiyoda ku Tokyo 100 0004 Japan...