NEC 78K0S/KB1+ User Manual page 395

Function Details of
Function
Serial UART mode
interface
UART6
Parity types and
operation
Continuous
transmission
TXBF6 during
continuous
transmission: Bit
1 of ASIF6
TXSF6 during
continuous
transmission: Bit
0 of ASIF6
Normal reception
Generation of
serial clock
Permissible baud
rate range during
reception
Multiplier MUL0: 16-bit
multiplication
result storage
register 0
MULC0: control
register 0
APPENDIX D LIST OF CAUTIONS
Take the relationship with the other party of communication into consideration
when setting the port mode register and port register. In order to avoid the
generation of unintended start bits (falling signals), set PM43 to 0 (output) after
having set P43 to 1.
Fix the PS61 and PS60 bits to 0 when the interface is used in LIN
communication operation.
Use the value of the TXBF6 flag to judge whether continuous transmission is
possible. Do not write the next transmit data, by making a judgment only by
the fact that the TXSF6 flag has been set to 1.
When the interface is used in LIN communication operation, the continuous
transmission function cannot be used. Make sure that asynchronous serial
interface transmission status register 6 (ASIF6) is 00H before writing transmit
data to transmit buffer register 6 (TXB6).
To transmit data continuously, write the first transmit data (first byte) to the
TXB6 register. Be sure to check that the TXBF6 flag is "0". If so, write the
next transmit data (second byte) to the TXB6 register. If data is written to the
TXB6 register while the TXBF6 flag is "1", the transmit data cannot be
guaranteed.
To initialize the transmission unit upon completion of continuous transmission,
be sure to check that the TXSF6 flag is "0" after generation of the transmission
completion interrupt, and then execute initialization. If initialization is executed
while the TXSF6 flag is "1", the transmit data cannot be guaranteed.
Be sure to read receive buffer register 6 (RXB6) 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.
Reception is always performed with the "number of stop bits = 1". The second
stop bit is ignored.
Be sure to read asynchronous serial interface reception error status register 6
(ASIS6) before reading RXB6.
Keep the baud rate error during transmission to within the permissible error
range at the reception destination.
Make sure that the baud rate error during reception satisfies the range shown
in (4) Permissible 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.
Although this register is manipulated with a 16-bit memory manipulation
instruction, it can be also manipulated with an 8-bit memory manipulation
instruction. When using an 8-bit memory manipulation instruction, however,
access the register by means of direct addressing.
Be sure to clear bits 1 to 7 to 0.
User's Manual U17446EJ3V1UD
Cautions
(13/19)
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