mc9s12xd256 Freescale Semiconductor, Inc, mc9s12xd256 Datasheet - Page 511

• Manufacturer Part Number: mc9s12xd256
• Description: Hcs12x Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

Enable single-wire operation by setting the LOOPS bit and the receiver source bit, RSRC, in SCI control
register 1 (SCICR1). Setting the LOOPS bit disables the path from the RXD pin to the receiver. Setting
the RSRC bit connects the TXD pin to the receiver. Both the transmitter and receiver must be enabled
(TE = 1 and RE = 1).The TXDIR bit (SCISR2[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.
11.4.8
In loop operation the transmitter output goes to the receiver input. The RXD pin is disconnected from the
SCI.
Enable loop operation by setting the LOOPS bit and clearing the RSRC bit in SCI control register 1
(SCICR1). Setting the LOOPS bit disables the path from the RXD pin 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).
11.5
11.5.1
See
11.5.2
11.5.2.1
Normal mode of operation.
To initialize a SCI transmission, see
Freescale Semiconductor
Section 11.3.2, “Register
Initialization/Application Information
Loop Operation
Reset Initialization
Modes of Operation
Run Mode
In single-wire operation data from the TXD pin is inverted if RXPOL is set.
In loop operation data from the transmitter is not recognized by the receiver
if RXPOL and TXPOL are not the same.
Figure 11-31. Loop Operation (LOOPS = 1, RSRC = 0)
Descriptions”.
Transmitter
MC9S12XDP512 Data Sheet, Rev. 2.17
Section 11.4.5.2, “Character
Receiver
NOTE
NOTE
Chapter 11 Serial Communication Interface (S12SCIV5)
Transmission”.
RXD
TXD
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