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APPENDIX B LIST OF CAUTIONS
User’s Manual U17894EJ9V0UD
915
(16/35)
Chapter
Cl
assi
fi
cati
on
Function
Details of
Function
Cautions
Page
A/D conversion
result register
(ADCR,
ADCRH) read
operation
When a write operation is performed to the A/D converter mode register (ADM),
analog input channel specification register (ADS), and A/D port configuration register
(ADPC), the contents of ADCR and ADCRH may become undefined.
Read the
conversion result following conversion completion before writing to ADM, ADS, and
ADPC.
Using a timing other than the above may cause an incorrect conversion
result to be read.
p.378
A/D conversion
result register
(ADCR,
ADCRH) read
operation
When a write operation is performed to the A/D converter mode register (ADM),
analog input channel specification register (ADS), and A/D port configuration register
(ADPC), the contents of ADCR and ADCRH may become undefined. Read the
conversion result following conversion completion before writing to ADM, ADS, and
ADPC.
Using a timing other than the above may cause an incorrect conversion
result to be read.
p.378
Chapter
1
Soft
A/D
converter
Starting the A/D
converter
Start the A/D converter after the AVREF0 and AVREF1 voltages (the reference voltages
for the D/A converter) stabilize.
p.379
When setting the D/A converter, be sure to set DACEN to 1 first. If DACEN = 0,
writing to a control register of the D/A converter is ignored, and, even if the register is
read, only the default value is read (except for port mode register 11 (PM11) and port
register 11 (P11)).
p.382
PER0:
Peripheral
enable register 0
Be sure to clear bit 1 of the PER0 register to 0.
p.382
Operation in
normal mode
Make the interval for writing DACSn of the same channel by one clock longer than
fCLK. If writing is successively performed, only the value written last will be converted.
p.385
Make the interval for generating a start trigger to the same channel by one clock
longer than fCLK.
If a start trigger is successively generated for every fCLK, D/A
conversion will be performed only at the first trigger.
p.386
Operation in
real-time output
mode
Note the following points in the procedure (i to iii) for outputting an arbitrary value in
<3>.
Do not generate the start trigger of the real-time output mode before enabling D/A
conversion operation in <3> after the value is set to the DACSn register in ii.
An arbitrary value cannot be output in <3> if the DACEN bit of the PER0 register is
cleared once after the value is set to the DACSn register in ii.
p.386
I/O function of
digital ports
alternately used
as ANO0, ANO1
The digital port I/O function, which is the alternate function of the ANO0 and ANO1
pins, does not operate during D/A conversion.
During D/A conversion, 0 is read from the P11 register in input mode.
p.387
P11, PM11
registers
Do not read/write the P11 register and do not change the setting of the PM11 register
during D/A conversion (otherwise the conversion accuracy may decrease).
p.387
ANO0, ANO1
pins
It is recommended that both the ANO0 and ANO1 pins be used as analog output pins
or digital I/O pins, that is, use these two channels for the same application (if these
pins are used for the different applications, the conversion accuracy may decrease).
p.387
DACSn register
In the real-time output mode, set the DACSn register value before the timer trigger is
generated. In addition, do not change the set value of the DACSn register while the
trigger signal is output.
p.387
Soft
Changing
operation mode
Before changing the operation mode, be sure to clear the DACEn bit of the DAM
register to 0 (D/A conversion stop).
p.387
Port alternately
used as ANO0
or ANO1 pin
When using the port that functions alternately as the ANO0 or ANO1 pin, use it as the
port input with few level changes.
p.387
Chapter
1
2
Hard
D/A
converter
Applying power
to and
disconnecting
power from
AVREF1 and AVREF0
Stop the conversion performed by the D/A converter when supplying AVREF1 or
AVREF0 (the reference voltages for the A/D converter) starts or stops.
p.387