When using an internal oscillator in a LIN system, it is necessary to raise the break
detection threshold one bit time. Under the worst case timing conditions allowed in LIN,
it is possible that a 0x00 data character can appear to be 10.26 bit times long at a slave
running 14% faster than the master. This would trigger normal break detection circuitry
designed to detect a 10-bit break symbol. When the LBKDE bit is set, framing errors are
inhibited and the break detection threshold changes from 10 bits to 11 bits, preventing
false detection of a 0x00 data character as a LIN break symbol.
Address: Base address + h offset
Bit 7 6 5 4 3 2 1 0
Read
LBKDIF RXEDGIF
0
RXINV RWUID BRK13 LBKDE
RAF
Write
Reset
0 0 0 0 0 0 0 0
UARTx_S2 field descriptions
Field Description
7
LBKDIF
LIN Break Detect Interrupt Flag
LBKDIF is set when the LIN break detect circuitry is enabled and a LIN break character is detected.
LBKDIF is cleared by writing a 1 to it.
0 No LIN break character has been detected.
1 LIN break character has been detected.
6
RXEDGIF
RxD Pin Active Edge Interrupt Flag
RXEDGIF is set when an active edge, falling if RXINV = 0, rising if RXINV=1, on the RxD pin occurs.
RXEDGIF is cleared by writing a 1 to it.
0 No active edge on the receive pin has occurred.
1 An active edge on the receive pin has occurred.
5
Reserved
This field is reserved.
This read-only field is reserved and always has the value 0.
4
RXINV
Receive Data Inversion
Setting this bit reverses the polarity of the received data input.
NOTE: Setting RXINV inverts the RxD input for all cases: data bits, start and stop bits, break, and idle.
0 Receive data not inverted.
1 Receive data inverted.
3
RWUID
Receive Wake Up Idle Detect
RWUID controls whether the idle character that wakes up the receiver sets the IDLE bit.
0 During receive standby state (RWU = 1), the IDLE bit does not get set upon detection of an idle
character.
1 During receive standby state (RWU = 1), the IDLE bit gets set upon detection of an idle character.
2
BRK13
Break Character Generation Length
Table continues on the next page...
Chapter 40 Universal Asynchronous Receiver/Transmitter (UART1 and UART2)
KL25 Sub-Family Reference Manual, Rev. 3, September 2012
Freescale Semiconductor, Inc. 757
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