APPENDIX D LIST OF CAUTIONS
User’s Manual U16899EJ2V0UD
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Chapter
Cl
assi
fi
cati
on
Function Details
of
Function
Cautions Page
Hard
When the Ring-OSC clock is selected as the clock to be supplied to the CPU, the
clock of the Ring-OSC oscillator is divided and supplied as the count clock. If the
base clock is the Ring-OSC clock, the operation of serial interface UART0 is not
guaranteed.
p. 275
Soft
Make sure that bit 6 (TXE0) and bit 5 (RXE0) of the ASIM0 register = 0 when
rewriting the MDL04 to MDL00 bits.
p. 275
Hard
BRGC0: Baud
rate generator
control register
0
The baud rate value is the output clock of the 5-bit counter divided by 2.
p. 275
POWER0,
TXE0, RXE0:
Bits 7, 6, and 5
of ASIM0
Clear POWER0 to 0 after clearing TXE0 and RXE0 to 0 to set the operation stop
mode.
To start the operation, set POWER0 to 1, and then set TXE0 and RXE0 to 1.
p. 276
UART mode
Take relationship with the other party of communication when setting the port
mode register and port register.
p. 277
UART
transmission
After transmit data is written to TXS0, do not write the next transmit data before
the transmission completion interrupt signal (INTST0) is generated.
p. 280
Be sure to read receive buffer register 0 (RXB0) even if a reception error occurs.
Otherwise, an overrun error will occur when the next data is received, and the
reception error status will persist.
p. 281
Reception is always performed with the “number of stop bits = 1”. The second
stop bit is ignored.
p. 281
UART reception
Be sure to read asynchronous serial interface reception error status register 0
(ASIS0) before reading RXB0.
p. 281
Keep the baud rate error during transmission to within the permissible error range
at the reception destination.
p. 284
Baud rate error
Make sure that the baud rate error during reception satisfies the range shown in
(4) Permissible baud rate range during reception.
p. 284
Chapter 13
Soft
Serial
interface
UART0
Allowable baud
rate range
during reception
Make sure that the baud rate error during reception is within the permissible error
range, by using the calculation expression shown below.
p. 286
Hard
The TXD6 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. 288
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 TXD6 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. 288
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 UART6 is used in the LIN communication operation.
p. 288
Do not write data to TXB6 when bit 1 (TXBF6) of asynchronous serial interface
transmission status register 6 (ASIF6) is 1.
p. 294
Chapter 14
Soft
Serial
interface
UART6
TXB6: Transmit
buffer register 6
Do not refresh (write the same value to) TXB6 by software during a
communication operation (when bit 7 (POWER6) and bit 6 (TXE6) of
asynchronous serial interface operation mode register 6 (ASIM6) are 1 or when
bit 7 (POWER6) and bit 5 (RXE6) of ASIM6 are 1).
p. 294