Information

UARTx_S2 field descriptions (continued)
Field Description
0 LSB (bit0) is the first bit that is transmitted following the start bit. Further, the first bit received after the
start bit is identified as bit0.
1 MSB (bit8, bit7 or bit6) is the first bit that is transmitted following the start bit, depending on the setting
of C1[M] and C1[PE]. Further, the first bit received after the start bit is identified as bit8, bit7, or bit6,
depending on the setting of C1[M] and C1[PE].
4
RXINV
Receive Data Inversion
Setting this field reverses the polarity of the received data input. In NRZ format, a one is represented by a
mark and a zero is represented by a space for normal polarity, and the opposite for inverted polarity. In
IrDA format, a zero is represented by short high pulse in the middle of a bit time remaining idle low for a
one for normal polarity. A zero is represented by a short low pulse in the middle of a bit time remaining idle
high for a one for inverted polarity.This field is automatically set when C7816[INIT] and C7816[ISO7816E]
are enabled and an initial character is detected in T = 0 protocol mode.In EN709 mode, this bit affects the
polarity of bits the same as it does in normal mode.
NOTE: Setting RXINV inverts the RxD input for data bits, start and stop bits, break, and idle. When
C7816[ISO7816E] is set/enabled, only the data bits and the parity bit are inverted.
0 Receive data is not inverted.
1 Receive data is inverted.
3
RWUID
Receive Wakeup Idle Detect
When RWU is set and WAKE is cleared, this field controls whether the idle character that wakes the
receiver sets S1[IDLE]. This field must be cleared when C7816[ISO7816E] is set/enabled.
0 S1[IDLE] is not set upon detection of an idle character.
1 S1[IDLE] is set upon detection of an idle character.
2
BRK13
Break Transmit Character Length
Determines whether the transmit break character is 10, 11, or 12 bits long, or 13 or 14 bits long. See for
the length of the break character for the different configurations. The detection of a framing error is not
affected by this field. Transmitting break characters
0 Break character is 10, 11, or 12 bits long.
1 Break character is 13 or 14 bits long.
1
LBKDE
LIN Break Detection Enable
Selects a longer break character detection length. While LBKDE is set, S1[RDRF], S1[NF], S1[FE], and
S1[PF] are prevented from setting. When LBKDE is set, see . Overrun operationLBKDE must be cleared
when C7816[ISO7816E] is set.
0 Break character is detected at one of the following lengths:
• 10 bit times if C1[M] = 0
• 11 bit times if C1[M] = 1 and C4[M10] = 0
• 12 bit times if C1[M] = 1, C4[M10] = 1, and S1[PE] = 1
1 Break character is detected at length of 11 bit times if C1[M] = 0 or 12 bits time if C1[M] = 1.
0
RAF
Receiver Active Flag
RAF is set when the UART receiver detects a logic 0 during the RT1 time period of the start bit search.
RAF is cleared when the receiver detects an idle character when C7816[ISO7816E] is cleared/disabled.
When C7816[ISO7816E] is enabled, the RAF is cleared if the C7816[TTYPE] = 0 expires or the
C7816[TTYPE] = 1 expires.
Table continues on the next page...
Chapter 48 Universal Asynchronous Receiver/Transmitter (UART)
K20 Sub-Family Reference Manual, Rev. 1.1, Dec 2012
Freescale Semiconductor, Inc.
Preliminary
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