MC68HC912B32MFU8 MOTOROLA [Motorola, Inc], MC68HC912B32MFU8 Datasheet - Page 86

• Manufacturer Part Number: MC68HC912B32MFU8
• Description: 16-Bit Microcontroller
• Manufacturer: MOTOROLA [Motorola, Inc]

BTST — Baud Register Test
BSPL — Baud Rate Counter Split
BRLD — Baud Rate Reload
SC0CR1 — SCI Control Register 1
LOOPS — SCI LOOP Mode/Single Wire Mode Enable
WOMS — Wired-Or Mode for Serial Pins
RSRC — Receiver Source
M — Mode (select character format)
86
MOTOROLA
RESET:
LOOPS RSRC
Reserved for test function
Reserved for test function
Reserved for test function
Read or write anytime.
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 be-
comes high (IDLE line state) for RSRC = 0 and high impedance for RSRC = 1. Refer to Table 29.
This bit controls the two pins (TXD and RXD) associated with the SCI section.
When LOOPS = 1, the RSRC bit determines the internal feedback path for the receiver.
0
1
1
1
1
1
1
0 = SCI transmit and receive sections operate normally.
1 = SCI receive section is disconnected from the RXD pin and the RXD pin is available as general
0 = Pins operate in a normal mode with both high and low drive capability. To affect the RXD bit,
1 = Each pin operates in an open drain fashion if that pin is declared as an output.
0 = Receiver input is connected to the transmitter internally (not TXD pin)
1 = Receiver input is connected to the TXD pin
0 = One start, eight data, one stop bit
1 = One start, eight data, ninth data, one stop bit
purpose I/O. The receiver input is determined by the RSRC bit. The transmitter output is con-
trolled by the associated DDRS bit. Both the transmitter and the receiver must be enabled to
use the LOOP or the single wire mode.
that bit would have to be configured as an output (via DDRS) which is the single wire case when
using the SCI. WOMS bit still affects general-purpose output on TXD and RXD pins when SCI
is not using these pins.
LOOPS
Bit 7
x
0
0
0
1
1
1
0
DDS1(3)
WOMS
x
0
1
1
0
1
1
6
0
WOMS
0/1
x
1
1
x
0
1
RSRC
Table 29 Loop Mode Functions
5
0
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
(the pin is used as receiver input only, TXD = High Impedance)
Single wire mode with TXD output
Single wire mode for the receiving and transmitting (open-drain)
(the output is also fed back to receiver input, CMOS)
M
4
0
WAKE
3
0
Function of Port S Bit 1/3
ILT
2
0
PE
1
0
MC68HC912B32TS/D
Bit 0
PT
MC68HC912B32
0
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