APPENDIX D LIST OF CAUTIONS
User’s Manual U16899EJ2V0UD
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(12/24)
Chapter
Cl
assi
fi
cati
on
Function Details
of
Function
Cautions Page
ADM: A/D
converter mode
register
If data is written to ADM, a wait cycle is generated. Do not write data to ADM
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. 250
Be sure to clear bits 3 to 7 of ADS to 0.
p. 251
ADS: Analog
input channel
specification
register
If data is written to ADS, a wait cycle is generated. Do not write data to ADS
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. 251
When writing to the A/D converter mode register (ADM) and analog input channel
specification register (ADS), the contents of ADCR may become undefined. Read
the conversion result following conversion completion before writing to ADM and
ADS. Using timing other than the above may cause an incorrect conversion
result to be read.
p. 252
ADCR: A/D
conversion result
register
If data is read from ADCR, a wait cycle is generated. Do not read data from
ADCR 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. 252
PFM: Power-fail
comparison
mode register
If data is written to PFM, a wait cycle is generated. Do not write data to PFM
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. 253
PFT: Power-fail
comparison
threshold
register
If data is written to PFT, a wait cycle is generated. Do not write data to PFT 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. 253
Make sure the period of <1> to <3> is 14
µ
s or more.
p. 259
It is no problem if the order of <1> and <2> is reversed.
p. 259
<1> can be omitted. However, do not use the first conversion result after <3> in
this case.
p. 259
A/D conversion
operation
The period from <4> to <7> differs from the conversion time set using bits 5 to 3
(FR2 to FR0) of ADM. The period from <6> to <7> is the conversion time set
using FR2 to FR0.
p. 259
Make sure the period of <3> to <6> is 14
µ
s or more.
p. 259
It is no problem if order of <3>, <4>, and <5> is changed.
p. 259
<3> must not be omitted if the power-fail function is used.
p. 259
Soft
Power-fail
detection
function
The period from <7> to <11> differs from the conversion time set using bits 5 to 3
(FR2 to FR0) of ADM. The period from <9> to <11> is the conversion time set
using FR2 to FR0.
p. 259
Operating
current in
standby mode
The A/D converter stops operating in the standby mode. At this time, the
operating current can be reduced by clearing bit 7 (ADCS) of the A/D converter
mode register (ADM) to 0 (see Figure 12-2).
p. 262
Hard
ANI0 to ANI7
input range
Observe the rated range of the ANI0 to ANI7 input voltage. If a voltage of AV
REF
or higher and AV
SS
or lower (even in the range of absolute maximum ratings) is
input to an analog input channel, the converted value of that channel becomes
undefined. In addition, the converted values of the other channels may also be
affected.
p. 262
ADCR read has priority. After the read operation, the new conversion result is
written to ADCR.
p. 262
Chapter 12
Soft
A/D
converter
Conflict
operation
ADM or ADS write has priority. ADCR write is not performed, nor is the
conversion end interrupt signal (INTAD) generated.
p. 262