APPENDIX D LIST OF CAUTIONS
User’s Manual U16899EJ2V0UD
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Chapter
Cl
assi
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Function Details
of
Function
Cautions Page
Soft
WTM: Watch
timer operation
mode register
Do not change the count clock and interval time (by setting bits 4 to 7 (WTM4 to
WTM7) of WTM) during watch timer operation.
p. 227
Chapter 9
Hard
Watch
timer
Interrupt
request
When operation of the watch timer and 5-bit counter is enabled by the watch timer
mode control register (WTM) (by setting bits 0 (WTM0) and 1 (WTM1) of WTM to
1), the interval until the first interrupt request (INTWT) is generated after the
register is set does not exactly match the specification made with bits 2 and 3
(WTM2 and WTM3) of WTM. Subsequently, however, the INTWT signal is
generated at the specified intervals.
p. 230
If data is written to WDTM, a wait cycle is generated. Do not write data to WDTM
when the CPU is operating on the subsystem clock and the high-speed system
clock is stopped. For details, see CHAPTER 32 CAUTIONS FOR WAIT.
p. 235
Set bits 7, 6, and 5 to 0, 1, and 1, respectively (when “Ring-OSC cannot be
stopped” is selected by the option byte, other values are ignored).
p. 235
After reset is released, WDTM can be written only once by an 8-bit memory
manipulation instruction. If writing attempted a second time, an internal reset
signal is generated. If the source clock to the watchdog timer is stopped,
however, an internal reset signal is generated when the source clock to the
watchdog timer resumes operation.
p. 235
WDTM cannot be set by a 1-bit memory manipulation instruction.
p. 235
WDTM:
Watchdog timer
mode register
If “Ring-OSC can be stopped by software” is selected by the option byte and the
watchdog timer is stopped by setting WDCS4 to 1, the watchdog timer does not
resume operation even if WDCS4 is cleared to 0. In addition, the internal reset
signal is not generated.
p. 235
If a value other than ACH is written to WDTE, an internal reset signal is
generated. If the source clock to the watchdog timer is stopped, however, an
internal reset signal is generated when the source clock to the watchdog timer
resumes operation.
p. 235
If a 1-bit memory manipulation instruction is executed for WDTE, an internal reset
signal is generated. If the source clock to the watchdog timer is stopped,
however, an internal reset signal is generated when the source clock to the
watchdog timer resumes operation.
p. 235
Soft
WDTE:
Watchdog timer
enable register
The value read from WDTE is 9AH (this differs from the written value (ACH)).
p. 235
When “Ring-
OSC cannot be
stopped” is
selected by
option byte
In this mode, operation of the watchdog timer absolutely cannot be stopped even
during STOP instruction execution. For 8-bit timer H1 (TMH1), a division of the
Ring-OSC can be selected as the count source, so clear the watchdog timer using
the interrupt request of TMH1 before the watchdog timer overflows after STOP
instruction execution. If this processing is not performed, an internal reset signal
is generated when the watchdog timer overflows after STOP instruction
execution.
p. 237
Chapter 10
Hard
Watchdog
timer
When “Ring-
OSC can be
stopped by
software” is
selected by
option byte
In this mode, watchdog timer operation is stopped during HALT/STOP instruction
execution. After HALT/STOP mode is released, counting is started again using
the operation clock of the watchdog timer set before HALT/STOP instruction
execution by WDTM. At this time, the counter is not cleared to 0 but holds its
value.
p. 238
Soft
A/D conversion must be stopped before rewriting bits FR0 to FR2 to values other
than the identical data.
p. 250
Chapter 12
Hard
A/D
converter
ADM: A/D
converter mode
register
For the sampling time of the A/D converter and the A/D conversion start delay
time, see (11) in 12.6 Cautions for A/D Converter.
p. 250