MMC2107 Datasheet, PDF (368/618 Pages) –

Freescale Semiconductor, Inc.
Serial Communications Interface Modules (SCI1 and SCI2)
Enable loop operation by setting the LOOPS bit and clearing the RSRC
bit in 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).
The WOMS bit in SCICR1 configures the TXD pin for full CMOS drive or
for open-drain drive. WOMS controls the TXD pin during both normal
operation and loop operation.
16.15 I/O Ports
The SCIPORT register is associated with two pins:
• The TXD pin is connected to SCIPORT1.
• The RXD pin is connected to SCIPORT0.
The SCI data direction register (SCIDDR) configures the pins as inputs
or outputs. The SCI pullup and reduced drive register (SCIPURD)
controls pin drive capability and enables or disables pullups. The WOMS
bit in SCICR1 configures output ports as full CMOS drive outputs or as
open-drain outputs.
Table 16-9. SCI Port Control Summary
Pullup Enable Control
Register
Bit
Reset
State
Reduced Drive Control
Register
Bit
Reset
State
SCIPURD PUPSCI
0
SCIPURD RDPSCI
0
Wired-OR Mode Control
Register
Bit
Reset
State
SCICR1 WOMS
CMOS
drive
Technical Data
368
Serial Communications Interface Modules (SCI1 and SCI2)
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MMC2107 – Rev. 2.0
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