MC9S08GB60A Datasheet, PDF (181/302 Pages) Freescale Semiconductor, Inc – HCS08 Microcontrollers

11.2.5 SCI Status Register 2 (SCIxS2)
This register has one read-only status flag. Writes have no effect.
Serial Communications Interface (S08SCIV1)
R
W
Reset
Field
0
RAF
7
6
5
4
3
2
1
0
0
0
0
0
0
0
0
RAF
0
0
0
0
0
0
0
0
= Unimplemented or Reserved
Figure 11-9. SCI Status Register 2 (SCIxS2)
Table 11-6. SCIxS2 Register Field Descriptions
Description
Receiver Active Flag — RAF is set when the SCI receiver detects the beginning of a valid start bit, and RAF is
cleared automatically when the receiver detects an idle line. This status flag can be used to check whether an
SCI character is being received before instructing the MCU to go to stop mode.
0 SCI receiver idle waiting for a start bit.
1 SCI receiver active (RxD input not idle).
11.2.6 SCI Control Register 3 (SCIxC3)
R
W
Reset
Field
7
R8
6
T8
5
TXDIR
7
6
5
4
3
2
1
0
R8
0
T8
TXDIR
ORIE
NEIE
FEIE
PEIE
0
0
0
0
0
0
0
0
= Unimplemented or Reserved
Figure 11-10. SCI Control Register 3 (SCIxC3)
Table 11-7. SCIxC3 Register Field Descriptions
Description
Ninth Data Bit for Receiver — When the SCI is configured for 9-bit data (M = 1), R8 can be thought of as a ninth
receive data bit to the left of the MSB of the buffered data in the SCIxD register. When reading 9-bit data, read
R8 before reading SCIxD because reading SCIxD completes automatic flag clearing sequences which could
allow R8 and SCIxD to be overwritten with new data.
Ninth Data Bit for Transmitter — When the SCI is configured for 9-bit data (M = 1), T8 may be thought of as a
ninth transmit data bit to the left of the MSB of the data in the SCIxD register. When writing 9-bit data, the entire
9-bit value is transferred to the SCI shift register after SCIxD is written so T8 should be written (if it needs to
change from its previous value) before SCIxD is written. If T8 does not need to change in the new value (such
as when it is used to generate mark or space parity), it need not be written each time SCIxD is written.
TxD Pin Direction in Single-Wire Mode — When the SCI is configured for single-wire half-duplex operation
(LOOPS = RSRC = 1), this bit determines the direction of data at the TxD pin.
0 TxD pin is an input in single-wire mode.
1 TxD pin is an output in single-wire mode.
MC9S08GB60A Data Sheet, Rev. 2
Freescale Semiconductor
181