MC68HC12 MOTOROLA [Motorola, Inc], MC68HC12 Datasheet - Page 286

• Manufacturer Part Number: MC68HC12
• Description: The MC68HC912DT128A microcontroller unit (MCU) is a 16-bit device composed of standard on-chip peripherals including a 16-bit central processing unit
• Manufacturer: MOTOROLA [Motorola, Inc]

SC0SR1/SC1SR1 — SCI Status Register 1
Multiple Serial Interface
Technical Data
286
RESET:
TDRE
Bit 7
1
TC
6
1
TDRE — Transmit Data Register Empty Flag
TC — Transmit Complete Flag
The bits in these registers are set by various conditions in the SCI
hardware and are automatically cleared by special acknowledge
sequences. The receive related flag bits in SCxSR1 (RDRF, IDLE,
OR, NF, FE, and PF) are all cleared by a read of the SCxSR1 register
followed by a read of the transmit/receive data register low byte.
However, only those bits which were set when SCxSR1 was read will
be cleared by the subsequent read of the transmit/receive data
register low byte. The transmit related bits in SCxSR1 (TDRE and TC)
are cleared by a read of the SCxSR1 register followed by a write to
the transmit/receive data register low byte.
Read anytime (used in auto clearing mechanism). Write has no
meaning or effect.
New data will not be transmitted unless SCxSR1 is read before writing
to the transmit data register. Reset sets this bit.
Flag is set when the transmitter is idle (no data, preamble, or break
transmission in progress). Clear by reading SCxSR1 with TC set and
then writing to SCxDR.
0 = SCxDR busy
1 = Any byte in the transmit data register is transferred to the serial
0 = Transmitter busy
1 = Transmitter is idle
RDRF
5
0
shift register so new data may now be written to the transmit
data register.
Multiple Serial Interface
IDLE
4
0
OR
3
0
NF
2
0
MC68HC912DT128A — Rev 4.0
FE
1
0
Bit 0
PF
0
$00C4/$00CC
MOTOROLA