APPENDIX D LIST OF CAUTIONS
User’s Manual U16898EJ3V0UD
395
(9/17)
Chapter
Classification
Function Details
of
Function
Cautions Page
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. 173
Hard
Input
impedance of
ANI0 to ANI3
pins
In this A/D converter, the internal sampling capacitor is charged and sampling is
performed during sampling time.
Since only the leakage current flows other than during sampling and the current
for charging the capacitor also flows during sampling, the input impedance
fluctuates both during sampling and otherwise.
If the shortest conversion time of the reference voltage is used, to perform
sufficient sampling, it is recommended to make the output impedance of the
analog input source 1 k
Ω
or lower, or attach a capacitor of around 0.01
µ
F to 0.1
µ
F to the ANI0 to ANI3 pins (see Figure 10-19).
p. 173
Interrupt
request flag
(ADIF)
The interrupt request flag (ADIF) is not cleared even if the analog input channel
specification register (ADS) is changed.
Therefore, if an analog input pin is changed during A/D conversion, the A/D
conversion result and ADIF for the pre-change analog input may be set just
before the ADS rewrite. Caution is therefore required since, at this time, when
ADIF is read immediately after the ADS rewrite, ADIF is set despite the fact A/D
conversion for the post-change analog input has not ended.
When A/D conversion is stopped and then resumed, clear ADIF before the A/D
conversion operation is resumed.
p. 174
Conversion
results just after
A/D conversion
start
The first A/D conversion value immediately after A/D conversion starts may not
fall within the rating range if the ADCS bit is set to 1 within 1
µ
s after the ADCE bit
was set to 1, or if the ADCS bit is set to 1 with the ADCE bit = 0. Take measures
such as polling the A/D conversion end interrupt request (INTAD) and removing
the first conversion result.
p. 174
Chapter 10
Soft
A/D
converter
A/D conversion
result register
(ADCR,
ADCRH) read
operation
When a write operation is performed to the A/D converter mode register (ADM)
and analog input channel specification register (ADS), the contents of ADCR and
ADCRH may become undefined. Read the conversion result following conversion
completion before writing to ADM and ADS. Using a timing other than the above
may cause an incorrect conversion result to be read.
p. 174
Hard
The T
X
D6 output inversion function inverts only the transmission side and not the
reception side. To use this function, the reception side must be ready for
reception of inverted data.
p. 176
If clock supply to serial interface UART6 is not stopped (e.g., in the HALT mode),
normal operation continues. If clock supply to serial interface UART6 is stopped
(e.g., in the STOP mode), each register stops operating, and holds the value
immediately before clock supply was stopped. The T
X
D6 pin also holds the value
immediately before clock supply was stopped and outputs it. However, the
operation is not guaranteed after clock supply is resumed. Therefore, reset the
circuit so that POWER6 = 0, RXE6 = 0, and TXE6 = 0.
p. 176
UART mode
If data is continuously transmitted, the communication timing from the stop bit to
the next start bit is extended two operating clocks of the macro. However, this
does not affect the result of communication because the reception side initializes
the timing when it has detected a start bit. Do not use the continuous
transmission function if the interface is incorporated in LIN.
p. 176
Chapter 11
Soft
Serial
Interface
UART6
TXB6: Transmit
buffer register 6
Do not write data to TXB6 when bit 1 (TXBF6) of asynchronous serial interface
transmission status register 6 (ASIF6) is 1.
p. 182