XC912BC32CFU8 Motorola Semiconductor Products, XC912BC32CFU8 Datasheet - Page 208

• Manufacturer Part Number: XC912BC32CFU8
• Description: M68HC12B Family Data Sheet
• Manufacturer: Motorola Semiconductor Products

Serial Interface
Data Sheet
208
WOMS — Wired-OR Mode for Serial Pins
RSRC — Receiver Source Bit
M — Mode Bit (select character format)
WAKE — Wakeup by Address Mark/Idle Bit
If the DDRS bit associated with the TXD pin is set during the LOOPS = 1, the
TXD pin outputs the SCI waveform. If the DDRS bit associated with the TXD pin
is clear during the LOOPS = 1, the TXD pin becomes high (IDLE line state) for
RSRC = 0 and high impedance for RSRC = 1. Refer to
This bit controls the two pins (TXD and RXD) associated with the SCIx section.
When LOOPS = 1, the RSRC bit determines the internal feedback path for the
receiver.
LOOPS
0 = Pins operate in a normal mode with both high and low drive capability. To
1 = Each pin operates in an open drain fashion if that pin is declared as an
0 = Receiver input connected to the transmitter internally
1 = Receiver input connected to the TXD pin
0 = One start, eight data, one stop bit
1 = One start, eight data, ninth data, one stop bit
0 = Wakeup by IDLE line recognition
1 = Wakeup by address mark (last data bit set)
0
1
1
1
1
1
1
affect the RXD bit, that bit would have to be configured as an output (via
DDS0/2) which is the single-wire case when using the SCI. WOMS bit
still affects general-purpose output on TXD and RXD pins when SCIx is
not using these pins.
output.
(not TXD pin)
RSRC
0
0
0
1
1
1
x
DDS1
Table 14-2. Loop Mode Functions
Serial Interface
x
0
1
1
0
1
1
WOMS
0/1
x
0
1
x
0
1
Normal operations
LOOP mode without TXD output
(TXD = high impedance)
LOOP mode with TXD output (CMOS)
LOOP mode with TXD output (open-drain)
Single-wire mode without TXD output
(pin is used as receiver input only,
TXD = high Impedance)
Single-wire mode with TXD output
(The output is also fed back to receiver
input, CMOS.)
Single wire mode for the receiving and
transmitting (open-drain)
Function of Port S Bit 1/3
M68HC12B Family — Rev. 8.0
Table
14-2.
MOTOROLA