APPENDIX D LIST OF CAUTIONS
User’s Manual U17446EJ3V1UD
391
(9/19)
Chapter
Cl
assi
fi
cati
on
Function Details
of
Function
Cautions Page
PMC2: Port
mode control
register 2
When PMC20 to PMC23 are set to 1, the P20/ANI0 to P23/ANI3 pins cannot
be used as port pins. Be sure to set the pull-up resistor option registers (PU20
to PU23) to 0 for the pins set to A/D converter mode.
p.168
pp.
Make sure the period of <1> to <4> is 1
μ
s or more.
169, 173
pp.
It is no problem if the order of <1> and <2> is reversed.
169, 173
<1> can be omitted. However, ignore the data resulting from the first
conversion after <4> in this case.
p.173
Soft
A/D converter
operations
The period from <5> to <8> differs from the conversion time set using bits 5 to
3 (FR2 to FR0) of ADM. The period from <7> to <8> is the conversion time
set using FR2 to FR0.
p.173
Operating current
in STOP mode
To satisfy the DC characteristics of the supply current in the STOP mode,
clear bit 7 (ADCS) and bit 0 (ADCE) of the A/D converter mode register (ADM)
to 0 before executing the STOP instruction.
p.176
Hard
Input range of
ANI0 to ANI3
Observe the rated range of the ANI0 to ANI3 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.176
ADCR, ADCRH read has priority. After the read operation, the new
conversion result is written to ADCR, ADCRH.
p.176
Soft
Conflicting
operations
ADM or ADS write has priority. ADCR, ADCRH write is not performed, nor is
the conversion end interrupt signal (INTAD) generated.
p.176
Noise
countermeasures
To maintain the 10-bit resolution, attention must be paid to noise input to the
AV
REF
pin and pins ANI0 to ANI3.
<1> Connect a capacitor with a low equivalent resistance and a high
frequency response to the power supply.
<2> Because the effect increases in proportion to the output impedance of the
analog input source, it is recommended that a capacitor be connected
externally, as shown in Figure 10-19, to reduce noise.
<3> Do not switch the A/D conversion function of the ANI0 to ANI3 pins to
their alternate functions during conversion.
<4> The conversion accuracy can be improved by setting HALT mode
immediately after the conversion starts.
p.176
The analog input pins (ANI0 to ANI3) are also used as input port pins (P20 to
P23).
When A/D conversion is performed with any of ANI0 to ANI3 selected, do not
access port 2 (P20 to P23) while conversion is in progress; otherwise the
conversion resolution may be degraded.
p.177
Chapter 1
0
Hard
A/D
converter
ANI0/P20 to
ANI3/P23
If a digital pulse is applied to the pins adjacent to the pins currently used for
A/D conversion, the expected value of the A/D conversion may not be
obtained due to coupling noise. Therefore, do not apply a pulse to the pins
adjacent to the pin undergoing A/D conversion.
p.177
Содержание 78K0S/KB1+
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