MMC2107 Datasheet, PDF (338/618 Pages) –

Freescale Semiconductor, Inc.
Serial Communications Interface Modules (SCI1 and SCI2)
Table 16-3. SCI Normal, Loop, and Single-Wire Mode Pin Configurations
SCI
Mode
Receiver
Input
RXD
Pin
Function
Transmitter
Output
TXD
Pin
Function
0 X Normal Tied to RXD input buffer Receive pin X Tied to TXD output driver Transmit pin
0
1
Loop
Tied to transmitter output
General-
purpose I/O
1 Single-wire Tied to TXD
0 Tied to receiver input only
1
Tied to receiver input
and TXD output driver
0 No connection
1 Tied to TXD output driver
None (idles high)
Transmit pin
Receive pin
Transmit pin
WOMS — Wired-OR Mode Select Bit
This read/write bit configures the TXD and RXD pins for open-drain
operation. This allows all of the TXD pins to be tied together in a
multiple-transmitter system. WOMS also affects the TXD and RXD
pins when they are general-purpose outputs. External pullup resistors
are necessary on open-drain outputs. Reset clears WOMS.
1 = TXD and RXD pins open-drain when outputs
0 = TXD and RXD pins CMOS drive when outputs
RSRC — Receiver Source Bit
This read/write bit selects the internal feedback path to the receiver
input when LOOPS = 1. Reset clears RSRC.
1 = Receiver input tied to TXD pin when LOOPS = 1
0 = Receiver input tied to transmitter output when LOOPS = 1
M — Data Format Mode Bit
This read/write bit selects 11-bit or 10-bit frames. Reset clears M.
1 = Frames have 1 start bit, 9 data bits, and 1 stop bit.
0 = Frames have 1 start bit, 8 data bits, and 1 stop bit.
Technical Data
338
Serial Communications Interface Modules (SCI1 and SCI2)
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MMC2107 – Rev. 2.0
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