NEC 78K0 Series User Manual page 376

(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, see Figure 15-2 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 the
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)
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
376
CHAPTER 15 SERIAL INTERFACE UART6
Figure 15-23. SBF Reception
2 3 4 5
1 2 3 4
Preliminary User's Manual U17260EJ3V1UD
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5 6 7 8
10 11
9 10