MMC2114 MOTOROLA [Motorola, Inc], MMC2114 Datasheet - Page 392

• Manufacturer Part Number: MMC2114
• Description: M CORE Microcontrollers
• Manufacturer: MOTOROLA [Motorola, Inc]

Serial Communications Interface Modules (SCI1 and SCI2)
17.13 Single-Wire Operation
Advance Information
392
Serial Communications Interface Modules (SCI1 and SCI2)
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.
Enable single-wire operation by setting the LOOPS bit and the RSRC bit
in SCICR1. Setting the LOOPS bit disables the path from the RXD pin 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 WOMS bit in the SCICR1 register configures the TXD pin for full
CMOS drive or for open-drain drive. WOMS controls the TXD pin in both
normal operation and in single-wire operation. When WOMS is set, the
DDR bit for the TXD pin does not have to be cleared for transmitter to
receive data.
Freescale Semiconductor, Inc.
Figure 17-25. Single-Wire Operation (LOOPS = 1, RSRC = 1)
TXD SCIDDR
TXD SCIDDR
For More Information On This Product,
BIT = 1
BIT = 0
Go to: www.freescale.com
TRANSMITTER
TRANSMITTER
RECEIVER
RECEIVER
NC
WOMS
MMC2114 • MMC2113 • MMC2112 — Rev. 1.0
RXD
RXD
TXD
TXD
GENERAL-PURPOSE I/O
GENERAL-PURPOSE I/O
MOTOROLA