NEC 78K0 User Manual page 291

(i) SBF reception
When the device is incorporated in LIN, the SBF (Synchronous Break Field) reception control function is
used for reception. For the reception operation of LIN, refer to Figure 13-2 LIN Reception Operation.
Reception is enabled when bit 7 (POWER6) of asynchronous serial interface operation mode register 6
(ASIM6) is set to 1 and then bit 5 (RXE6) of ASIM6 is set to 1. SBF reception is enabled when bit 6 (SBRT6)
of asynchronous serial interface control register 6 (ASICL6) is set to 1. In the SBF reception enabled status,
the R D6 pin is sampled and the start bit is detected in the same manner as the normal reception enable
X
status.
When the start bit has been detected, reception is started, and serial data is sequentially stored in receive
shift register 6 (RXS6) at the set baud rate. When the stop bit is received and if the width of SBF is 11 bits or
more, a reception completion interrupt request (INTSR6) is generated as normal processing. At this time, the
SBRF6 and SBRT6 bits are automatically cleared, and SBF reception ends. Detection of errors, such as
OVE6, PE6, and FE6 (bits 0 to 2 of asynchronous serial interface reception error status register 6 (ASIS6)) is
suppressed, and error detection processing of UART communication is not performed. In addition, data
transfer between receive shift register 6 (RXS6) and receive buffer register 6 (RXB6) is not performed, and
the reset value of FFH is retained. If the width of SBF is 10 bits or less, an interrupt does not occur as error
processing after the stop bit has been received, and the SBF reception mode is restored. In this case, the
SBRF6 and SBRT6 bits are not cleared.
1. Normal SBF reception (stop bit is detected with a width of more than 10.5 bits)
1
R D6
X
SBRT6
/SBRF6
INTSR6
2. SBF reception error (stop bit is detected with a width of 10.5 bits or less)
1
R D6
X
SBRT6
/SBRF6
INTSR6
"0"
Remark R D6: R D6 pin (input)
X X
SBRT6: Bit 6 of asynchronous serial interface control register 6 (ASICL6)
SBRF6: Bit 7 of ASICL6
INTSR6: Reception completion interrupt request
CHAPTER 13 SERIAL INTERFACE UART6
Figure 13-24. SBF Reception
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