When C2[RWU] is 1 and S2[RWUID] is 0, the idle character that wakes the receiver
does not set S1[IDLE] or the receive data register full flag, S1[RDRF]. The receiver
wakes and waits for the first data character of the next message which is stored in the
receive data buffer. When S2[RWUID] and C2[RWU] are set and C1[WAKE] is cleared,
any idle condition sets S1[IDLE] and generates an interrupt if enabled.
46.5.2.9.2 Address mark wakeup (C1[WAKE] = 1)
In this wakeup method, a logic 1 in the bit position immediately preceding the stop bit of
a frame clears C2[RWU] and wakes the UART. A logic 1 in the bit position immediately
preceeding the stop bit marks a frame as an address frame that contains addressing
information. All receivers evaluate the addressing information, and the receivers for
which the message is addressed process the frames that follow. Any receiver for which a
message is not addressed can set its C2[RWU] and return to the standby state. C2[RWU]
remains set and the receiver remains in standby until another address frame appears on
the unsynchronized receiver input signal.
A logic 1 in the bit position immediately preceding the stop bit clears the receiver's
C2[RWU] after the stop bit is received and places the received data into the receiver data
buffer. Note that if Match Address operation is enabled i.e. C4[MAEN1] or C4[MAEN2]
is set, then received frame is transferred to receive buffer only if the comparison matches.
Address mark wakeup allows messages to contain idle characters but requires that the bit
position immediately preceding the stop bit be reserved for use in address frames.
If module is in standby mode and nothing triggers to wake the UART, no error flag is set
even if an invalid error condition is detected on the receiving data line.
46.5.2.9.3 Match address operation
Match address operation is enabled when C4[MAEN1] or C4[MAEN2] is set. In this
function, a frame received by the RX pin with a logic 1 in the bit position of the address
mark is considered an address and is compared with the associated MA1 or MA2 register.
The frame is transferred to the receive buffer, and S1[RDRF] is set, only if the
comparison matches. All subsequent frames received with a logic 0 in the bit position of
the address mark are considered to be data associated with the address and are transferred
to the receive data buffer. If no marked address match occurs, then no transfer is made to
the receive data buffer, and all following frames with logic 0 in the bit position of the
address mark are also discarded. If both C4[MAEN1] and C4[MAEN2] are negated, the
receiver operates normally and all data received is transferred to the receive data buffer.
Functional description
KV4x Reference Manual, Rev. 2, 02/2015
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Preliminary
Freescale Semiconductor, Inc.
Summary of Contents for freescale KV4 Series
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