NXP Semiconductors freescale KV4 Series, Reference Manual

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The detection threshold for a break character can be adjusted when using an internal
oscillator in a LIN system by setting S2[LBKDE]. The UART break character detection
threshold depends on C1[M], C1[PE], S2[LBKDE] and C4[M10]. See the following
table.
Table 46-74. Receive break character detection threshold
LBKDE SBNS M M10 PE Threshold (bits)
0 0 0 — — 10
0 1 0 — — 11
0 0 1 0 — 11
0 1 1 0 — 12
0 0 1 1 1 12
0 1 1 1 1 13
1 — 0 — — 11
1 — 1 — — 12
While S2[LBKDE] is set, it will have these effects on the UART registers:
• Prevents S1[RDRF], S1[FE], S1[NF], and S1[PF] from being set. However, if they
are already set, they will remain set.
• Sets the LIN break detect interrupt flag, S2[LBKDIF], if a LIN break character is
received.
46.5.2.7 Hardware flow control
To support hardware flow control, the receiver can be programmed to automatically
deassert and assert RTS.
• RTS remains asserted until the transfer is complete, even if the transmitter is disabled
midway through a data transfer. See Transceiver driver enable using RTS for more
details.
• If the receiver request-to-send functionality is enabled, the receiver automatically
deasserts RTS if the number of characters in the receiver data register is equal to or
greater than receiver data buffer's watermark, RWFIFO[RXWATER].
• The receiver asserts RTS when the number of characters in the receiver data register
is less than the watermark. It is not affected if RDRF is asserted.
• Even if RTS is deasserted, the receiver continues to receive characters until the
receiver data buffer is full or is overrun.
• If the receiver request-to-send functionality is disabled, the receiver RTS remains
deasserted.
Functional description
KV4x Reference Manual, Rev. 2, 02/2015
1308
Preliminary
Freescale Semiconductor, Inc.