MC9S12T64 Datasheet, PDF (453/608 Pages) Motorola, Inc – Specification

Freescale Semiconductor, Inc.
Serial Communications Interface (SCI)
Functional Description
TRANSMITTER
RECEIVER
TXD Output Signal
TXD Input Signal
RxD
Figure 89 Single-Wire Operation (LOOPS = 1, RSRC = 1)
Enable single-wire operation by setting the LOOPS bit and the receiver
source bit, RSRC, in SCI control register 1 (SCIxCR1). Setting the
LOOPS bit disables the path from the RX input signal to the receiver.
Setting the RSRC bit connects the receiver input to the output of the TxD
pin driver. Both the transmitter and receiver must be enabled (TE=1 and
RE=1).The TXDIR bit (SCIxSR2[1]) determines whether the TxD pin is
going to be used as an input (TXDIR = 0) or an output (TXDIR = 1) in this
mode of operation.
Loop Operation
In loop operation the transmitter output goes to the receiver input. The
RX input signal is disconnected from the SCI.
TRANSMITTER
RECEIVER
TX Output Signal
RxD
Figure 90 Loop Operation (LOOPS = 1, RSRC = 0)
Enable loop operation by setting the LOOPS bit and clearing the RSRC
bit in SCI control register 1 (SCIxCR1). Setting the LOOPS bit disables
the path from the RX input signal to the receiver. Clearing the RSRC bit
connects the transmitter output to the receiver input. Both the transmitter
and receiver must be enabled (TE = 1 and RE = 1).
Serial Communications Interface (SCI)
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MC9S12T64Revision 1.1.1