MMC2107 Datasheet, PDF (366/618 Pages) –

Freescale Semiconductor, Inc.
Serial Communications Interface Modules (SCI1 and SCI2)
addresses match, the receiver processes the frames that follow. If the
addresses do not match, user code must put the receiver back to sleep
by setting the RWU bit. The RWU bit remains set and the receiver
remains on standby until another address frame appears on the RXD
pin.
The address mark clears the RWU bit before the stop bit is received and
sets the RDRF flag.
Address mark wakeup allows messages to contain idle frames but
requires that the most significant byte (MSB) be reserved for address
data.
NOTE: With the WAKE bit clear, setting the RWU bit after the RXD pin has been
idle can cause the receiver to wake up immediately.
16.13 Single-Wire Operation
Normally, the SCI uses the TXD pin for transmitting and the RXD pin for
receiving (LOOPS = 0, RSRC = X). In single-wire mode, the RXD pin is
disconnected from the SCI and is available as a general-purpose I/O pin.
The SCI uses the TXD pin for both receiving and transmitting.
In single-wire mode (LOOPS = 1, RXRC = 1), setting the data direction
bit for the TXD pin configures TXD as the output for transmitted data.
Clearing the data direction bit configures TXD as the input for received
data.
Technical Data
366
TXD SCIDDR
BIT = 1
TRANSMITTER
RECEIVER
WOMS
TXD
RXD GENERAL-PURPOSE I/O
TRANSMITTER
NC
TXD SCIDDR
BIT = 0
RECEIVER
TXD
RXD GENERAL-PURPOSE I/O
Figure 16-25. Single-Wire Operation (LOOPS = 1, RSRC = 1)
Serial Communications Interface Modules (SCI1 and SCI2)
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MMC2107 – Rev. 2.0
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